MAXCNCSAM - 2.14 mb

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MAXCNCSAM - 2.14 mb

44 Little Cahill Road
Cary, IL 60013
Ph: 847-639-8847
Fax: 849-639-8857
Email: [email protected]
New Product Notice!
Course Curriculum: Maximizing CNC Utilization
Dear CNC Instructor,
I constantly hear technical instructors voice their concerns about the number of students coming to their CNC
courses. While numbers vary from one area to another and from semester to semester, you too may be
concerned with maintaining a student base that justifies your CNC program. Wouldn’t it be nice if you could
find a whole new audience? That’s exactly what this ready-made curriculum will do for you!
This curriculum is aimed at experienced CNC people – people who already know CNC basics (they would
never come to your basic CNC courses) – but still want to improve their knowledge of CNC. You’ve
probably never seen many of them before. Maybe they’re self-taught. Maybe they’ve received their basic
CNC training on-the-job. Maybe they’ve been through machine tool builders’ courses. Or, of course, they
may have received their basic training from your school. The number of new potential students for this new
course is staggeringly more than the students now coming to your basic courses. You’ll have a whole new
audience! You may even have to limit attendance for the first few offerings of this course!
Enclosed is a brochure that describes the new curriculum in detail. We’ve also enclosed a single sheet
brochure aimed at potential attendees of this course. (This document is actually included with the curriculum
and can be used to help you promote the new course.) Here are just a few highlights.
•
All instructor materials are FREE with initial order of student manuals – Just have your bookstore place an
initial order for twenty student manuals. 625 page student manual is extremely comprehensive, and reinforces
your presentations. Our price to your bookstore is $95.00 each. Our suggested list price is $120.00. In
essence, the students in your first class will be acquiring the curriculum for you.
•
Download FREE samples – From our web site (www.cncci.com), you can download more about how we
intend the curriculums to be used, including complete outlines, samples of the slide shows, and a portion of the
student manual.
•
This curriculum has been developed during the teaching of live courses for over 12 years. The comments
printed in the brochure reflect these courses.
Thank you for taking the time to view this information. Admittedly, there’s a lot to see. If you have any
questions, be sure to contact me (847-639-8847).
Sincerely,
Mike Lynch
President
CNC Concepts, Inc.
P.S. Check out the Schools Forum on our web site (www.cncci.com). Listings are free and allow you to
promote your school’s CNC-related courses.
Getting Started With Maximizing CNC Utilization:
The need for higher level CNC training
CNC people get their CNC training in one of two ways. First, many machine tool builders,
colleges, vocational schools, technical schools, and universities offer courses that teach basic
CNC usage. In these courses, students learn how to program, setup, and run CNC machine
tools. Since almost all students are at entry level (at least when it comes to CNC), instructors
must keep presentations quite elementary. A student may just begin to grasp an important topic
when it’s time to move on to the next. The student isn’t ready for discussions that may take
what they just learned to the next level. And of course, safety must be the highest priority. But
since safety and efficiency almost always conflict, the methods they learn will not be the most
efficient. When the student finishes one of these courses, they’re ready to begin working with
CNC machine tools. It is unlikely, however, that they have a complete grasp on how to make
the best use of the machines they’ll be working with.
While a student coming out of a machine tool builder’s or technical school’s CNC courses may
not have a complete grasp of every related function, at least they have had some formal training.
Many CNC people are self-taught. Maybe they’ve taken over a position from someone that
moved on. They may have learned all they know from someone else in the company (likely
another self-taught individual). They’ve probably had to struggle through most problems,
eventually learning enough to make the machine do what they want it to. But again, it’s unlikely
that they’re making the most of the machines they’re working with.
While the sheer productivity of CNC machines often masks inappropriate methods, companies
are becoming more and more concerned with their CNC machine tools. Changes in
manufacturing including lowered lot sizes, shorter lead times, and improved quality requirements
(among other things) have most CNC-using companies struggling to maintain profit margins.
They need to improve their methods if they are to remain in business.
The most basic objective of this course curriculum is to help instructors relate concepts,
techniques, and ideas that will help students make they’re CNC machines more productive.
Note that it’s aimed at CNC people who already have some CNC experience, meaning you’ll
be drawing from an entirely new potential student base.
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The modules of Maximizing CNC Utilization
We divide the curriculum into eight modules. Each is self-sufficient, meaning you can pick and
choose those modules you wish to include in your course/s. While there is a little overlap,
especially among modules three, six, and seven, you can, of course, present all modules in one
course. We offer some suggestions about presenting this course a little later.
Module one: Basic premises (57 slides, about 1-1.5 hour presentation time)
This short, but important, module lays the groundwork for what is to come. Included are
presentations that acquaint students with important needs of CNC using companies. We
discuss application versus utilization and machine utilization versus personnel utilization to help
them understand the reasoning behind improving CNC machine utilization. We also introduce
the four CNC-using company types and discuss factors making up a company’s corporate
identity. Finally, we discuss the importance of value added principles in the CNC environment.
Module two: Review of CNC basics (346 slides, about 6-10 hours presentation time,
depending upon the current student level)
Since you won’t have control of how much previous experience your students have (not all of
them will have attended your school’s basic courses), you’ll want to make sure that they have a
good grasp of basic CNC principles before digging in to more advanced topics. Again, many
students coming to this course will be (for the most part) self-taught. It’s likely that they’ve
missed out on some important basic concepts and techniques. In the advance courses I’ve
taught myself, I’m always surprised at how often a so-called expert is unfamiliar with a very
basic CNC feature or function.
This module allows you to review the basics using our proven key concepts approach. There
are ten key concepts (see the instructor’s outline). We begin each key concept by introducing
the reasoning behind the key concept. Then we address how the key concept applies to
machining centers and then to turning centers.
Again, this is a review. Students should be quite familiar with the presentation –and if they are –
you’ll be able to buzz through quite quickly (possibly under six hours). But, if they’re
questioning each step along the way, it should be taken as a signal that more basic training is
needed.
SPECIAL SAFETY NOTE: Many of the techniques you’ll be showing later in the course
require a firm understanding of basic CNC practices. Misapplication could lead to serious
consequences including machine crashes and possible injury. You cannot present more
complex topics until students understand the basics.
Module three: Advanced implications of basic CNC features (911 slides, about 14-18
hours presentation time, depending upon questions, comments, and extra discussions)
Many CNC features have multiple uses. But most basic CNC courses introduce only the most
important use. Additionally, most basic courses don’t show all implications related to how a
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given feature can be best used to meet the company’s applications. If it’s a basic function, and
if it’s not commonly addressed in a basic CNC course, it’s included in this module. Included in
this lengthy module (the longest of the course) are presentations on parameters, N words, G
codes, M codes, and other CNC words. We also discuss advanced applications for tool
offsets, fixture offsets, and wear offsets. Again, see the instructor’s outline to see just how
comprehensive this module is.
Module four: Advanced CNC features, functions, and concepts (432 slides, about 2-8
hours presentation time, depending upon students’ interests)
There are many CNC features that are not addressed in basic courses. Admittedly, many of
these features will not be of interest to a given CNC user. However, this module gives you the
presentation material you need to discuss features like advanced interpolation types (helical,
cylindrical, polar coordinate, and nurbs), scaling, mirror image, coordinate rotation, and three
dimensional coordinate conversion. We also include presentations on certain machine
accessories like bar feeders, index chucks, U axis, and part catchers. Finally, we provide
materials for teaching some important CNC concepts like tool life management, qualifying CNC
programs, and appropriate documentation. Again, see the instructor’s outline for more on
what’s addressed in this module. Since many of the features in this module will not be of
interest to every attendee, it’s difficult to predict how long this discussion will be.
Module five: Parametric programming (556 slides, about 4-24 hours presentation time,
depending upon the level to which you want to go)
We’ve often said that parametric programming is CNC’s best kept secret. There are still many
in the industry that don’t know what it is, let alone how to take full advantage of it. These
materials allow you to dive into parametric programming as deep as you want to go. We stress
Fanuc’s version of parametric programming – custom macro B (the most popular version).
Note that many control manufacturers claim to be Fanuc-compatible, and use custom macro B
as their version of parametric programming.
If you just want to present a cursory view of what it is, (I like to include this presentation even in
my basic CNC courses) you’ll just be acquainting students with it’s applications and basic
features. This can be done quite quickly (under 4 hours). But if you want to present a full
course, these materials still allow you to do so. With limited time for practice (a workbook and
answer book is included with the instructor materials), this full course can be completed in about
16 hours. If you want to allow time (during class) for students to do the exercises, allow about
24 hours.
Module six: Setup time reduction (295 slides, about 7-9 hours presentation time,
depending upon students’ questions, comments, and discussions)
This is a very hot topic. All CNC using companies are concerned with how long their machines
are down between production runs. This module lets you first present the principles of setup
time reduction (that can be applied to any form of production equipment). We then offer
specific CNC-related techniques to improving setup time in the approximate order setups are
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made (tear down, work holding setup, cutting tools, program zero assignment, program loading,
program verification, and first workpiece inspection).
Module seven: Cycle time reduction (411 slides, about 7-9 hours presentation time,
depending upon students’ questions, comments, and discussions)
This is also a hot topic. All CNC using companies are concerned with how long it takes to
complete their production runs. As with setup time reduction, this module lets you first present
the principles of cycle time reduction. We then offer specific techniques to reducing cycle time
in four areas, workpiece load/unload, program execution time, tool maintenance, and preventive
maintenance.
Module eight: Spindle probe programming (519 slides, about 4-16 hours presentation
time, depending upon the level you wish to go)
Actually, the student manual includes discussions on several types of probes (spindle probes,
tool touch-off probes, and tool length measuring probes). However, the slide presentation is
limited to spindle probes.
Admittedly, most spindle probe uses depend solely on the probing programs supplied by the
probe manufacturer. Only a small percentage of probe-using companies develop their own
probing programs. For this reason, most students may not be very interested in learning how
probes are programmed. You may elect to simply introduce the basics (under 4 hours of
presentation time). But if you do need to teach a full course on spindle probe programming,
these materials let you do so. Presentations include introduction to probe programming,
applications for probing, how the probe works, calibration techniques, and writing spindle
probe programs.
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Presentation alternatives
As you can see, the Maximizing CNC Utilization curriculum is very comprehensive! Including
over 3,000 slides and a 625 page student manual, you’ll have plenty to do. Here are a few
suggestions for how you can use the curriculum.
The whole course
As you can see from our approximate presentation times, there is quite a variation based upon
student level, question, comments, extra discussions, and even how deeply you wish to dig into
the course content for certain topics.
When you total the “worst case” presentation times shown earlier, you’re looking at 86.5 hours
of presentation time. If you’re teaching in a seminar environment (consecutive full days), it’s
over ten days of presentation time. If you’re teaching an evening course two nights a week at
three hours per session, it will require about 14 weeks. Either way, this may be an excessive
amount of time for you, your school, and your students.
The CNC tune-up
One of the benefits of this curriculum is that each module will stand on it’s own. You can easily
pick and choose those modules that are appropriate for your needs. Here is one popular way
that will allow you to relate a great deal of information, yet minimizes the time required:
Module one: Basic premises (1.5 hours)
Module two: Review of basics (4 hours)
Module three: Advanced implications of basic features (10 hours)
Module four: Advanced CNC features, functions, and concepts (4 hours, just touching on items
of interest to everyone)
Module five: Parametric programming (12 hours, limiting time for practice in class)
Module six: Setup time reduction (7 hours)
Module seven: Cycle time reduction (7 hours)
Module eight: Probe programming (Skip)
With this popular course, there is 45.5 hours of presentation time. If teaching in a seminar
environment, it’s under six consecutive days. If teaching a night class two evenings a week for
three hours per session, it’s about an 8-week class.
We’re simply trying to give you some idea of what each module takes to present. The times
given are based upon my own experience in presenting the material. Of course, teaching times
will vary dramatically from one instructor to another. Also, these times allow no time for
reviewing material. Until you get some experience under your belt, you may want to allow even
more time for presentation.
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A two-day setup & cycle time reduction course
If teaching in a seminar environment, you can easily complete modules one, six, and seven in
two days. This should make an attractive course to companies in your area.
A two-day or three-day parametric programming course
Depending upon how much practice you want your students to do in class (remember – we
offer a workbook/answer book at an additional charge), you can easily complete the parametric
programming module in two days.
A two-day or three-day spindle probe programming course
In similar fashion, this curriculum includes everything you need to teach a probe programming
course. Note that spindle probes are programmed with parametric programming techniques.
You may want to make the parametric programming course a pre-requisite for this course. Or
be sure to allow time to explain the parametric programming features required for programming
spindle probes.
A one-day advanced techniques course
Though you may be a little pressed for time, you can include modules one and two for a very
intensive session!
A one-day setup time reduction course
You can easily complete module six in one day.
A one-day setup time reduction course
You can easily complete module seven in one day.
About the student manual
Again, the student manual includes all eight modules. For the most part, we recommend that
students purchase the entire manual, even if you’re not presenting the entire course. This makes
it easy for them to attend several sessions without having to purchase more materials. We do,
however, sell three manuals individually:
Parametric programming
Setup and Cycle time reduction
Probe programming
Take it on the road!
Any of these courses can be taught on an in-plant basis. There are many portable projection
systems available. See the various methods to display the slide shows later in this document.
The least expensive way (if you don’t have a portable projector) is a laptop computer with TVout and a television.
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Instructor materials
This curriculum truly minimizes the preparation you must do to get ready to teach! Here’s what
you get.
Microsoft PowerPoint slide presentations
PowerPoint is becoming the presentation software of choice by most presenters. These
presentations total over 3,000 slides to provide your visuals for the entire course. Note that
they’re developed in PowerPoint 97 (which is part of Microsoft Office 2000). These
presentations are included on a cd and most include audio narrations (you’ll need a multimedia
computer having a cd-rom drive to display and hear the presentations). There are nine slide
presentations included on the cd-rom. Each is locally named from INTRODUCTION.PPT
through MODULE 8_SPINDLE PROBES.PPT. These slide presentations can be accessed
right from the cd-rom or if your hard drive has room, you can copy them to your computer’s
hard drive (there’s over 300 megs of data).
Each slide includes a visual (in the form of a book) that lets students know the page number in
the student manual that is currently being discussed.
Guidance during slide shows
Each slide show includes audio narrations (we call guidance) to help you understand how to
make your presentations. Note that these narrations are not intended for your students. Each is
directed at the instructor getting ready to teach the course. A special icon on selected slides can
be activated to play the related narration.
Microsoft PowerPoint Viewer
Though we highly recommend that you have the actual PowerPoint software, we do include the
PowerPoint Viewer. It does allow you to display the slide shows, but you’ll have no way to
modify them. Additionally, the slide shows are quite long (most over 300 slides). PowerPoint
Viewer does not allow you to move around in the slide show nearly as easily as the actual
PowerPoint software.
Instructor’s outline
This outline serves two purposes. First, it lets you know exactly what is presented in each slide
module. You’ll be able to quickly see what’s included. Second, it shows the slide number for
each topic, making it easy to find slides as you move around in each slide show. For most
topics, it also includes student manual page numbers.
Workbook and answer book for Parametric Programming module
Since this portion of the course requires practice to master, we provide you with a way of
printing exercises and programming activities for students to do during this module. It can be
used as homework or done during class. We also provide you with the ability to print the
answer book.
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Ability to print slide show hard copy
PowerPoint allows you to print a hard copy of each slide show (Microsoft calls this printing
handouts). This may help you prepare if you don’t have the computer available. You can
include 4, 6, or 8 slides per page. Even so, there are over 3,000 slides. Be ready for a lot of
printing!
Promotional materials
We’ve even included a brochure that you can use to help you promote this course. It’s in the
“promotions” folder of the cd rom. It’s in PowerPoint format, so you can easily modify
anything you want! Note that there is space to include your school’s registration information
(logo, phone number, fax number, etc.).
Free phone assistance
Again, there’s a lot of information in this curriculum. If you have questions about any topic, we
welcome your phone calls (847-639-8847). Or email us at [email protected].
Student materials
While your presentation is an extremely important part of the learning environment, your
students must have reference material.
625 page student manual
This extremely comprehensive manual follows along with your presentation step-by-step and
again, the slide presentations reference page numbers throughout the course. Though we don’t
recommend actually reading from it, the slide presentations will be specifying the page number in
this manual that current information is being discussed so students can easily follow along in the
book. It will make for excellent homework reading assignments. And, it’s an excellent way for
students to review material once the course is finished. Because there is so much information in
the book, we recommend that students have some way to remember key pages (a highlighter
pen or post-it notes to act as tabs in the book work nicely). Note that the manual includes all
eight modules.
What you still need
In order to show the PowerPoint slide presentations to a group of people, you need the
following items.
A computer with Windows 98 (or higher) - Just about any current model computer will work.
For best results, Pentium class is recommended (minimum 64 megs internal). If using a desktop
computer, you can easily watch the monitor of the computer (facing your audience) to see the
slide show as slides are displayed behind you by the projection system. Since the left mouse
button advances the slides, you even have a remote slide advance button (as is commonly used
with a 35 mm slide projector). If portability is an issue, keep in mind that many of the
notebooks and sub-notebooks have ample power to run the presentation software. However,
be careful in your selection. Many notebooks do not allow you to send data out through the
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VGA port and see the slide show on the LCD screen of the notebook at the same time.
Without this ability, you may have to turn around to see your slides, which can be distracting to
your audience. Also, for maximum flexibility, look for a laptop that has the TV-OUT feature.
This lets you send composite video to any television that has a TV-IN port with a simple RCA
cable.
Microsoft PowerPoint Software (PowerPoint 97 version was used to create the slide
show) - Though you can display all presentations with PowerPoint Viewer (included with this
curriculum), you will need Microsoft PowerPoint if you intend to modify the slide shows given in
this curriculum (and to easily get around and start the slide show from any slide). We highly
recommend that you have this ability. This software can be found in any computer store for a
price of about $250.00 (it also comes with most editions of Microsoft Office). You will find
this to be a very powerful presentation-generating program; one you can use to develop your
own slide shows for other courses (or of course, modify those in this course curriculum).
A way of displaying the screen show - You have several alternatives in this regard. Most
involve using a device that takes data from the VGA port of your personal computer. First,
many schools already have a projection system that can display information from a personal
computer. Basically, anything that can be shown on the computer screen can be displayed
through the projection system. Second, you can use a device that sits on top of an overhead
projector to display your screen shows. In essence, this device makes a transparency of what
ever is on the display screen of the computer (I don’t like this kind because the light from the
overhead is very bright and hurts my eyes). Third, and especially if price is a concern, you can
use a simple scan converter (about $200.00 - $300.00) and display your screen show on any
television that has a video in connector (as most do). Note that many laptops are now coming
with a TV-OUT port, having this scan converter built in to the computer. If you must use the
RF connector of the television (where an antenna plugs in), an RF converter must be purchased.
Since there are so many alternatives for displaying your slide shows, we welcome phone calls
(847) 639-8847 if you have questions about your alternatives.
A note about the students you’ll attract
In my experience, experienced CNC people have a rather narrow focus. They know a lot
about the things they must do every day, but little or nothing about other important CNC-related
topics. I’m always amazed by how surprised experienced CNC people are about many
relatively basic features they just haven’t been exposed to. For example, a person that does
general purpose CNC machining will know little about five axis machining – and vise versa. Be
sure to take advantage of your students’ strong points. As you present the course, be sure to
solicit questions and comments each step along the way. We encourage student participation
quite often during the slide presentations. The more you can get people to contribute during the
class, the better the class will be. And you may be able to collect ideas for future classes!
Remember that your students for this course will have (possibly extensive) CNC experience.
I’ve found that most catch right on to the presentations being made, even for those topics that
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they’ve never been exposed to. With the exception of the parametric programming module,
you can minimize the tutorial method you’re probably using to teach your basic CNC courses.
While reviews are still helpful, they can be minimized. Instead of lengthy reviews at the
beginning of each session, I simply poll the class for questions. When students have questions,
I’ll dig back in as deep as necessary to make sure they understand. And I will, of course, bring
everyone up to speed on where we left off in the last session, but I do minimize review time.
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Putting It All Together
Getting Ready To Teach
As stated earlier, though these course curriculums dramatically reduce the amount of
preparation you must do, they do not eliminate it completely. And as any experienced instructor
will agree, the key to successful presentations is in becoming comfortable with the material you
present. And the only way to get comfortable is through adequate preparation.
Before your first course:
Skim the entire curriculum (at least those modules included in your current course) - Though
you do not have to be perfectly comfortable with every detail of the curriculum to begin
teaching, you will at least need to understand where the course is going. You can use the
course outline, guidance in the slide shows, and student manual to gain an appreciation for the
material being presented.
Before beginning each module:
Get comfortable will all discussions in the module - While some modules are relatively
short, most are lengthy. Be sure you feel comfortable with all points you need to make before
you begin teaching. Again, use the course outline and student manual to increase your comfort
level with the entire module.
Before you deliver a session:
Get ready to teach! - Study the lesson plan, guidance, and slide presentation in order to gain
an understanding of key points that must be delivered during your presentation. Because
modules vary in length, be prepared to review material covered in previous sessions if
appropriate.
During your presentation of each session:
Tell them what you’re going to tell them - The lesson plan (key points in the slide show at
the beginning of each module) will help you prepare your students for what they will be learning.
While you don’t have to dwell on this slide too long, it will help them know what is coming up.
Tell them - Go though the session, using your slide show as a guide. Be sure to point out the
page numbers and sections in the student manual where the information is also included for their
own independent study. Be sure everyone is catching on. Encourage participation, questions,
and comments. In fact, some of the best suggestions for future additions to your class will come
from students. You’ll be getting some pretty high level attendees, so take advantage of this
opportunity. Have a blackboard or overhead available for making special points.
Tell them what you told them - The lesson summary (included in the slide show for each
module) will let you summarize the key points of each lesson.
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As you get deeper into the course:
Review often - No student will retain every word of every presentation you make during a
course as lengthy as these. On average, you should spend about 10% to 20% of your session
time in review, depending upon how well your students are doing. The more problems they are
having, the more time you should spend on review.
Let students know where they stand - Be sure everyone knows how they are doing as they
progress through the course.
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INSTRUCTOR TIME OUT LINE FOR MAX I MIZING CNC UTILIZATION
Mod ule one: Ba sic Prem ises 1-1
Time for pre sent ing mod ule one: 1-1.5 hours
Slide: Description:
2
Les son plan
3
De cep tive ness of ma chine pro duc tiv ity
8
Uti li za tion ver sus ap pli ca tion
11
Ma chine uti li za tion vs personell utilization
19
Com pany di ver sity
22
Com pany types
23
Fac tors con trib ut ing to com pany pro file
37
Con flict in volv ing cor po rate iden tity
43
Def i ni tion of CNC en vi ron ment
46
Value added prin ci ples in man u fac tur ing
53
Com pla cency in the CNC en vi ron ment
46
Re view of ba sic themes
Mod ule two: Re view of CNC Ba sics 2-1
Slide: Description:
2
How did you get your train ing?
6
The key con cepts ap proach 2-1
9
Key con cept num ber one - Know your machine from a pro gram mer’s view point 2-2
10
The im por tance of ba sic ma chin ing prac tice
2-2
11
Ma chining cen ter con fig u ra tions 2-3
39
Ma chining cen ter pro gram ma ble func tions
2-4
40
Turn ing cen ter con fig u ra tions 2-5
49
Turn ing cen ter pro gram ma ble func tions 2-7
50
More on spin dle speed and feedrate con trol
2-9
52
Un der stand ing pro gram zero 2-10
164
Ab so lute ver sus in cre men tal mo tions 2-10
165
De ter mining pro gram zero as sign ment values 2-11
181
The two ways to as sign pro gram zero 2-11
184
Key con cept num ber two - You must prepare to write pro grams 2-13
193
Pre pare the ma chin ing pro cess 2-15
198
Doing the math 2-17
202
Check the re quired tool ing 2-17
205
Plan the work hold ing set-up 2-18
208
Key con cept num ber three - You must under stand the three most ba sic mo tion types
2-20
209
-Mo tion com mon al i ties 2-20
210
G00 Rapid mo tion (also called po si tion ing)
2-20
211
G01 lin ear in ter po la tion (straight line mo tion)
2-21
CNC Concepts, Inc.
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G02 and G03 cir cu lar mo tion com mands
2-22
Ma chining cen ter ex am ple
Turn ing cen ter ex am ple
Key con cept num ber four - You must un derstand the com pen sa tion types 2-25
Tool length com pen sa tion 2-26
Cut ter ra dius com pen sa tion 2-28
Fix ture off sets 2-31
Wear off sets 2-35
Tool nose ra dius com pen sa tion 2-40
Ge om e try off sets 2-44
Key con cept num ber five - Pro grams must
be struc tured with a strict for mat 2-47
Rea sons for pro gram for mat ting 2-47
How to use the for mats 2-48
Pro gram Start-Up For mat: 2-49
Tool End ing For mat: 2-49
Tool Start-Up For mat: 2-49
Pro gram End ing For mat: 2-49
Turning cen ter us ing ge om e try off sets to assign pro gram zero 2-50
Tool end ing for mat 2-50
Tool start-up for mat 2-50
Pro gram end ing for mat 2-50
Key con cept num ber six - Spe cial pro gramming fea tures 2-50
Les son three - Re view of setup & op er a tion
ba sics 2-62
Key con cept num ber seven - Know your machine from an op er a tor’s view point 2-62
Setup tasks ver sus pro duc tion main tain ing
tasks 2-62
Tasks re lated to set ting up 2-62
Tasks re lated to main tain ing pro duc tion 2-66
The two op er a tion pan els 2-68
The con trol panel 2-68
The ma chine panel 2-70
Key con cept num ber eight - The three
modes of op er a tion 2-72
The man ual mode 2-72
The man ual data in put mode 2-72
The man ual data in put po si tion of the mode
switch 2-73
Key con cept num ber nine - Know the most
im por tant op er a tion pro ce dures 2-74
The most im por tant pro ce dures 2-75
Key con cept num ber ten - Safely ver i fy ing
pro grams 2-75
Machining Center Programming and Operation
Page 1
Time Out line
Mod ule three: Ad vanced im pli ca tions of ba sic fea tures
Slide: Description:
2
Pre sen ta tion plan
4
Un der stand ing pa ram e ters 3-1
7
Di ver sity of pa ram e ters
11
Eight bit bi nary type 3-2
19
Whole num ber type 3-2
22
Im por tance of back ing up pa ram e ters 3-2
25
Doc u menting in the pro gram 3-3
28
Pro gram head ers 3-3
32
Tool in for ma tion 3-4
36
At ev ery pro gram stop 3-6
37
Sim ple setup in struc tions 3-6
38
De scribing changes made af ter a dis pute
3-7
39
Doc u menting some thing out of the or di nary
3-7
40
Getting mes sages into pro grams for con trols
that do not dis play mes sages 3-8
43
Block de lete tech niques (also called op tional
block skip) 3-9
47
Using block de lete mid-command 3-9
51
Con flicting words in a com mand 3-10
56
Trial ma chin ing 3-11
58
Trial bor ing on a ma chin ing cen ter 3-11
82
Trial turn ing on a turn ing cen ter 3-13
96
Elim i nating tool pres sure when fin ish ing on
turn ing cen ters 3-14
98
Con clu sion to trial ma chin ing with block delete 3-17
100
Using block de lete with un ex pected rough
stock 3-17
103
An other op tional stop 3-19
106
Spe cial note about mul ti ple ap pli ca tions
3-20
109
Se quence num ber tech niques 3-20
112
Elim i nating with lim ited mem ory ca pac ity
3-20
115
Using for re start blocks 3-20
119
Se quence num bers as state ment la bels
3-22
124
Looping with block de lete 3-22
125
Changing ma chin ing or der 3-23
131
G code com mon al i ties 3-26
134
Max i mum num ber of G codes per com mand
3-26
137
How to monitor 3-27
140
Un der stand ing G code groups 3-27
143
Ini tial ized G codes
146
Safety blocks
151
G00 & G01 rapid and straight line mo tion for
po si tion ing (not cut ting) 3-28
151
What is your max i mum feedrate? 3-28
Page 2
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481
511
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Which is faster, G00 or G01? 3-28
Using G01 for fast feed ap proach 3-31
G01 - Straight line cut ting mo tion (also
called lin ear in ter po la tion) 3-32
Ef fi ciency of ba sic mo tion types 3-32
Min i mizing cor ner round ing 3-33
G03 & G03 - cir cu lar mo tion com mands
3-33
Which way is clock wise? 3-33
Lim i ta tion of the R word 3-34
Di rec tional vec tors 3-34
Arc lim i ta tions 3-34
Full cir cle in one com mand 3-35
Arc in and out tech niques 3-35
G04 - Dwell tech niques 3-36
Can you spec ify the dwell pe riod in num ber
of spin dle rev o lu tions? 3-36
Re lieving tool pres sure 3-36
Are you dwell ing to over come ma chine problems? 3-37
Poorly in ter faced M codes 3-37
G09 - one-shot ex act stop check com mand
3-38
G10 - data set ting by pro grammed command 3-38
How G10 works 3-39
En tering tool length and cut ter ra dius compen sa tion val ues for ma chin ing cen ters 3-39
Can you read off set val ues?
Set ting pa ram e ters from within the pro gram
G17, G18, & G19 - plane se lec tion commands 3-44
Plane se lec tion with right an gle heads 3-45
Cir cu lar com mands 3-46
Plane se lec tion on turn ing cen ters 3-50
G20 & G21 - Inch and met ric se lec tion 3-50
How to se lect the inch or met ric mode 3-51
How to tell which mode you’re in
Ad van tages of the met ric mode
G32 - thread cut ting com mand 3-57
Com par i son to G01
Using G32 for tap ping 3-58
G40, G41, & G42 - cut ter ra dius com pen sation for ma chin ing cen ters and tool nose radius com pen sa tion for turn ing cen ters 3-58
The two ways to use off sets 3-59
How cut ter ra dius com pen sa tion works 3-59
Alarms and pos si ble causes 3-61
Other lim i ta tions of cut ter ra dius com pen sation 3-65
Do you re ally need con trol based tool nose
ra dius com pen sa tion? 3-69
Ma chining on both sides of but ton tool 3-69
CNC Concepts, Inc.
Time Out line
Mod ule three con tin ued: Sec ond file (labled B)
Slide: Description
1
Tool length compensation
4
Using sec ond ary off sets with tool length
com pen sa tion 3-71
10
G50 - Spin dle lim iter for turn ing cen ters 3-72
13
Chuck changes 3-72
18
Out-of-round workpieces 3-73
28
Bar feed ers that can not keep up with the
main spin dle 3-73
47
G52 - tem po rary shift of pro gram zero on
ma chin ing cen ters 3-75
64
G53 - rapid move ment rel a tive to the machine’s zero re turn po si tion 3-77
67
An other way to send the ma chine to the
zero re turn po si tion 3-77
70
Use with man ual pal let chang ers 3-78
75
Com mon tur ret in dex po si tion on turn ing
cen ters 3-78
79
G54-G59 - fix ture off sets 3-78
82
The two ways to use fix ture off sets 3-78
92
Shifting the point of ref er ence for pro gram
zero as sign ment value en tries 3-78
95
Subplates
104
Hor i zon tal ma chin ing cen ters
111
Deal ing with align ment prob lems af ter a
crash 3-82
115
48 fix ture off set op tion 3-83
118
What can a spin dle probe do for you? 3-83
121
Run ning out of fix ture off sets? 3-83
125
G60 - sin gle di rec tion po si tion ing 3-84
131
G61 - ex act stop check mode 3-86
132
G64 - nor mal cut ting mode 3-86
133
G70 - Turn ing cen ter fin ish ing cy cle 3-86
137
Using G70 to re peat com mands 3-86
144
G71 & G72 - rough turn ing and fac ing 3-87
147
Using G71 or G72 to semi-finish 3-87
155
Spin dle range chang ing within G71 3-88
162
Re tract amount with G71 and G72 3-89
167
G76 - thread ing cy cle 3-89
171
Max i mum feedrate when thread ing 3-89
174
What is thread chamfering? 3-89
186
Threading pa ram e ters
189
Taper thread ing
182
Mul ti ple start threads 3-91
198
Using the E word when thread ing 3-93
201
G73-G89 - hole ma chin ing canned cy cles on
ma chin ing cen ters 3-93
204
Pa ram e ters re lated to hole ma chin ing
canned cy cles 3-94
213
L0 with canned cy cles 3-94
216
Canned cy cles in the in cre men tal mode 3-96
CNC Concepts, Inc.
219
222
226
231
236
285
288
296
324
325
328
334
337
340
343
350
353
354
355
358
361
365
368
375
378
384
387
G90 & G91 - ab so lute and in cre men tal
mode 3-97
Using both in one com mand 3-97
Other ap pli ca tions for the in cre men tal mode
3-97
G96 - con stant sur face speed mode for turning cen ters 3-98
Elim i nating spin dle dead time when us ing
con stant sur face speed 3-98
X, Y, Z, A, B, C - axis des ig na tion words
3-101
Which value do you pro gram?
Re ducing rapid ap proach dis tance 3-101
F word tech niques 3-103
S word tech niques 3-103
Range se lec tion on ma chin ing cen ters
T word tech niques for turn ing cen ters 3-104
Right or left hand tools? 3-104
Can celing wear off sets with T0 3-105
Ap pli ca tions for sec ond ary wear off sets
3-106
T word tech niques for ma chin ing cen ters
3-115
Must you load tools se quen tially? 3-115
Ori ent the spin dle on the move ment to the
tool change po si tion 3-115
M code tech niques 3-115
Scour your ma chine tool builder’s pro gramming man ual to learn more about the available M codes 3-115
Inconsistencies
M codes you may not agree with
Do you have some M codes that are not fully
in ter faced? 3-117
M41 & M42 - spin dle range chang ing on
Cor rect way to de ter mine spin dle range
M98 & M99 - subprogramming com mands
3-119
Ap pli ca tions for subprogramming 3-119
Mod ule four: Ad vanced CNC fea tures, func tions, and
concepts
Slide Description:
2
Mod ule four les son plan
7
Spe cial in ter po la tion types 4-1
9
He li cal in ter po la tion 4-1
11
Ba sic ter mi nol ogy 4-2
44
Thread mill ing cut ters 4-3
49
Your ap proach to thread mill ing 4-4
52
Pro gramming con sid er ations 4-5
58
Ex am ple thread mill ing pro gram
Page 3
Time Out line
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84
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87
113
115
117
121
126
149
151
153
155
166
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369
371
373
377
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397
420
425
430
Page 4
Spi ral in ter po la tion for taper thread mill ing
4-7
Cy lin dri cal in ter po la tion 4-8
Why cy lin dri cal in ter po la tion is requierd
Pro gramming consideratins
Nurbs in ter po la tion 4-11
Po lar co or di nate in ter po la tion 4-11
Ad di tional fea tures of turn ing cen ters with
live tool ing 4-12
Pro gramming a ro tary axis 4-14
Co or di nate sys tem
Poly gon turn ing 4-20
Ex tended G codes 4-21
G15 & G16 - po lar co or di nates for ma chining cen ters 4-21
Ba sic use
How G52 helps
G50 & G51 - Scaling 4-21
Words involved
G50.1 & G51.1 - Mir ror im age com mands
4-22
Application
Words involved
On a turn ing cen ter?
G68 & G69 - co or di nate ro ta tion for ma chining cen ters 4-24
Words involved
G68 & G69 - Three di men sional co or di nate
con ver sion 4-25
3d Ma chining 4-25
Bar feed ers for turn ing cen ters 4-28
When to bar feed
A subprogram for barfeeding
A cus tom macro for bar feed ing
Im proving the ef fi ciency of bar feed ers on
Part catch ers 4-37
Pro gramming for the U axis on ma chin ing
cen ters 4-37
De scrip tion and ap pli ca tion
Con stant sur face speed
Ex am ple program
Tool life man age ment sys tems 4-44
Gen eral de scrip tion and ap pli ca tion
Qual ifying CNC pro grams 4-47
Pro gram prep a ra tion and stor age de vice issues 4-55
Is sues re lated to pro gram stor age 4-60
Pro gram trans fer de vice is sues 4-60
Pro gram ver i fi ca tion de vice is sues 4-62
Mod ule five: Para met ric Pro gramming
Slide: Description
2
Les son plan for mod ule five
3
In tro duc tion to para met ric pro gram ming 5-1
4
What is para met ric pro gram ming? 5-1
5
Com par i son to subprogramming 5-1
10
Com par i son to com puter pro gram ming 5-3
12
Com par i son to canned cy cles 5-2
14
Ap pli ca tion cat e go ries 5-3
15
Fam ilies-of-parts 5-3
18
User cre ated canned cy cles 5-6
38
Util ities 5-7
44
Geo met ric shapes 5-9
50
Driving ac ces sory de vices 5-11
53
Lim i ta tions 5-11
54
In tro duc tion to fea ture types 5-13
57
In tro duc tion to vari ables 5-15
58
What are vari ables? 5-15
65
Ar gu ments 5-16
66
Ar gu ments with user cre ated canned cy cle
ap pli ca tions 5-16
72
Lo cal vari ables with ar gu ment as sign ment
num ber one 5-21
88
Ar gu ment as sign ment examples
118
Com mon vari ables 5-23
120
Cal cu lating val ues up front
122
As ar gu ments in part fam i lies
125
Re taining val ues from pro gram ot pro gram
130
Part fam ily ex am ple
153
Per ma nent com mon vari ables 5-24
155
Setting your own sys tem con stants 5-25
165
Sys tem vari ables 5-26
167
Arith me tic ca pa bil i ties 5-28
170
Ba sic func tions 5-28
171
Com bining op er a tions to form an ex pres sion
5-28
173
Trig o nom e try func tions 5-30
183
Square root
185
Ab so lute value
187
Rounding func tions 5-31
188
Ap pli ca tions for round ing 5-31
199
Ex am ple show ing arithmentic
204
Logic and pro gram flow con trol 5-43
231
State ment la bels 5-43
234
Un con di tional branch ing 5-43
235
Ap pli ca tions for un con di tional branch ing
5-44
238
Con di tional branch ing 5-47
240
The con di tional ex pres sion 5-47
246
Ap pli ca tions for con di tional branch ing 5-49
250
Ar gu ment flags 5-49
251
To set defaluts
CNC Concepts, Inc.
Time Out line
256
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266
267
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312
316
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325
350
352
535
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389
390
392
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411
415
428
441
446
448
449
452
474
489
492
497
500
501
507
511
518
523
524
527
528
534
540
Ar gu ment er ror trap ping
Testing for other er rors
Loops 5-55
A loop de fined
Com par i son to subprogramming
A loop that counts to ten 5-55
Steps to gen er at ing loops 5-58
When is a loop re quired? 5-59
How many times must the loop be ex e cuted? 5-60
What changes each time through the loop?
Any other in i tial ized val ues?
Do you need a prior move ment?
What must hap pen each time?
Peck drill ing example
Sys tem vari ables 5-72
Alarm gen er a tion
Part coun ter ex am ple
Stop with mes sage
Timers
Sin gle block sup pres sion
Feed hold sup pres sion
Feedrate over ride sup pres sion
Tapping ex am ple
Ac cess to ma chin ing cen ter offsets
Fix ture off sets 5-74
Sim u lating cut ter comp
Sim u lating wear off sets
Check ing off sets for cor rect ness
Turn ing cen ter wear off sets 5-74
Turn ing cen ter ge om e try off sets 5-75
Im proving G50 com mands
Ac cess to cur rent po si tion 5-81
Man ual prob ing ex am ple
Tool length mea sur ing ex am ple
Testing ma chine po si tion
Ac cessing turn ing cen ter po si tion
Modal G codes
Other CNC Fea tures 5-97
Modal call ing com mands
Ar gu ment as sign ment num ber two
User de fined G codes
User de fined M codes
Pro tec tion for im por tant pro grams 5-97
Out putting data
Ap proaching and ver i fy ing para met ric programs 5-101
Ap proaching fam ily-of-parts ap pli ca tions
5-101
Ap proaching user-created canned cy cle appli ca tions 5-116
Ap proaching util ity ap pli ca tions
CNC Concepts, Inc.
541
547
Ap proaching com plex geo met ric shape appli ca tions 5-121
Mis takes be gin ners are prone to mak ing
5-127
Mod ule six: Setup time re duc tion
Slide: Description
2
Setup time re duc tion prin ci ples 6-1
2
Introduction
25
Setup time de fined 6-3
33
Eval u ate cur rent meth ods
37
Two setup task types
48
The three ways to re duce setup time 6-5
72
Four steps to setup re duc tion
77
Avail able re sources
85
Setup time re duc tion tech niques 6-10
94
Prep a ra tion and or ga ni za tion for setup 6-10
100
Tool cart
102
Priortize set ups
103
Non pro duc tion time
104
Job or der planning
108
Workholding setup
110
Re lated tasks
111
Elim i nating workholding setup
114
Moving workholding setup off line
119
Fa cil i tating workholding set ups
124
Cut ting tool is sues 6-17
125
Re lated tasks
126
Elim i nating cut ting tool tasks
130
Moving cut ting tool tasks off line
133
Tool length com pen sa tion off set
measurment
145
Fa cil i tating cut ting tool tasks
152
Pro gram zero as sign ment 6-29
153
Re lated tasks
154
De scrip tion of pro gram zero
156
Eliinating pro gram zero as sign ment tasks
161
De ter mining pro gram zero as sign ment values up front
173
Shifting point of ref er ence for pro gram zero
assignment
207
Pro gramming pro gram zero as sign ment values
209
Turn ing cen ter pro gram zero as sign ment
212
Fa cil i tating pro gram zero as sign ment tasks
215
Pro gram de vel op ment 6-43
219
Moving off line
220
Facilitating
226
Pro gram trans fer
227
Re lated tasks
228
Eliminating
231
Moving off line
Page 5
Time Out line
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240
241
243
263
270
278
285
294
Fa cil i tating pro gram transfers
CNC Pro gram ver i fi ca tion 6-45
Re lated tasks
Def i ni tion of pro gram ver i fi ca tion
Trial ma chin ing
Using block de lete to fa cil i tate trial ma chining
Changing ma chin ing or der
Pro gram op ti miz ing
Pro gramming cut ting con di tions with
variables
Mod ule seven: Cy cle time re duc tion
Slide: Description:
2
Pre sen ta tion plan
3
Cy cle time re duc tion prin ci ples 7-1
6
Cy cle time de fined 7-1
25
Eval u ate your cur rent meth ods
31
Watch for pro cess im prove ments
39
Task types for cy cle time re duc tion 7-2
65
The three ways to re duce cy cle time 7-2
66
One sec ond rule
71
How fast can your ma chines rapid? 7-4
81
Re ducing workpiece load ing and un load ing
time 7-5
96
Re ducing CNC pro gram ex e cu tion time 7-9
99
Things we think of as be yond our control
104
Ef fi cient pro gram for mat ting 7-9
105
The ef fects of spe cial pro gram ming fea tures
7-9
127
How M codes re late to pro gram ex e cu tion
time 7-12
134
Re ducing rapid ap proach dis tance 7-14
162
Pro gramming ef fi cient mo tions 7-16
178
Ap proach and re tract in all axes 7-17
187
Which is faster G00 or G01?
194
Turn ing cen ter sug ges tions 7-18
195
Moving warm-up time off-line 7-18
200
Pro gramming spin dle range changes ef ficiently 7-19
218
The ef fects of con stant sur face speed on cycle time 7-20
271
How tool ing style can af fect pro gram ex e cution time 7-24
287
Im proving the ef fi ciency of bar feed ers on
307
Ma chining cen ter sug ges tions 7-26
308
Mul ti ple iden ti cal workpieces 7-26
310
Ef fi cient au to matic tool changer pro gramming 7-27
311
Range chang ing
320
Re ducing tool main te nance time 7-32
320
Sug ges tions for mov ing off line
Page 6
373
404
Helping op er a tors make off set ad just ments
How pre ven tive main te nance helps
Mod ule eight: Spin dle probe programmign
Slide: Description
3
The con cept of prob ing 8-1
22
Ap pli ca tions for prob ing 8-7
23
Setup help 8-8
71
In-process gaug ing 8-17
104
Util ities 8-21
108
How Touch Probes Work 8-22
115
Sig nal trans mis sion types
119
Bat tery con sid er ations
124
Un der stand ing over shoot and droop 8-26
174
Cal i bra tion to com pen sate for over shoot and
droop 8-29
210
Probing cy cles 8-44
228
CNC Com mands Used With Probing 8-45
232
G31 - skip cut ting com mand 8-45
257
G00 and G01 - rapid and straight line mo tion
com mands 8-47
265
G10 - off set set ting by pro grammed command 8-47
282
G20 and G21 - inch and met ric modes 8-48
294
Tool length com pen sa tion can cel - G49 8-50
298
Co or di nate ma nip u la tion com mands 8-50
301
M codes needed for prob ing
313
Cus tom macro B sys tem vari ables of im portance when prob ing 8-53
319
#2000 se ries - ac cess to tool off sets 8-53
338
#3000 se ries - mis cel la neous con trols of machine func tions 8-54
361
#5000 se ries - ac cess to the ma chine’s current po si tion 8-56
382
Lo cating a probed surface
414
Pro gramming for setup help ap pli ca tions
8-64
453
Pro gramming in-process gaug ing ap pli cations 8-85
516
Pro gramming util ity ap pli ca tions 8-97
CNC Concepts, Inc.
Beyond the basics
Maximizing CNC Utilization
Getting the most from your
CNC machining centers and turning centers
Eight Mod ules!
1: Basic premises
• 2: Review of basic CNC usage
•
•
3: Advanced implications of basic features
4: Advanced CNC features, functions, and concepts
• 5: Parametric programming
•
•
6: Setup time reduction
7: Cycle time reduction
• 8: Programming spinlde probes
•
Pub lished By:
© Copyright 2000, CNC Concepts, Inc.
NOTICE!!
Written by Mike Lynch
This man ual is pro tected by copy right laws of the United States Gov ernment. No part of this man ual may be re pro duced with out the writ ten consent of CNC Con cepts, Inc. Ad di tional cop ies of this doc u ment must be
pur chased di rectly from CNC Con cepts, Inc. (847) 639-8847
Doc u ment num ber: S000061
Ba sic Premises
Mod ule one
1.1. Basic Premises
We will be gin by pre sent ing the most im por tant themes that are stressed through out the course. While
you may not agree with ev ery de tail of what is said in this dis cus sion since your spe cific expe ri ences may
dif fer from the gen er al iza tions we pres ent, these im por tant prin ci ples do ap ply nicely to the vast ma jor ity
of CNC-using com pa nies. Un der stand ing and ac cept ing these prin ci ples will help you get the most from
this course.
1.1.1. The im por tance of im prov ing CNC ma chine uti li za tion
All CNC-using com pa nies want to get the most from their CNC ma chine tools. And of course, each machine’s max i mum out put po ten tial is di rectly tied to how well it is be ing uti lized. How ever, there is much
con tro versy and con fu sion re lated to just how a com pany should best uti lize their CNC ma chine tools.
Given the di ver sity of CNC ma chine ap pli ca tions, what is right for one com pany will be in ap pro pri ate for
an other. In this course, not only will we ex pose many ways to im prove CNC uti li za tion, we will also clarify which meth ods are most ap pro pri ate based upon a com pany’s spe cific needs.
1.1.1.1. CNC ma chine uti li za tion ver sus ap pli ca tion
Do not con fuse uti li za tion with ap pli ca tion. Uti li za tion is the ef fec tive ness level of the CNC ma chine tool.
The pro duc tiv ity of the CNC ma chine is, of course, dic tated by how well it is be ing uti lized. The ap pli cation for the CNC ma chine is sim ply the kind of work it is per form ing.
Con sider for ex am ple, two com pa nies that own iden ti cal CNC ver ti cal ma chin ing cen ters. One com pany
makes molds and uses their CNC ma chin ing cen ter for ma chin ing com plex mold cav i ties. The other company makes manifolds and uses their CNC ma chin ing cen ter to drill (many) holes in man i fold plates.
They may have a lim ited num ber of dif fer ent man i folds and run them over and over again. The mold appli ca tion is, of course, much more so phis ti cated than the man i fold ap pli ca tion. But it would be in cor rect
to say that one com pany is underutilizing their ma chin ing cen ter based solely upon its ap pli c a tion. The
com pany that uses the CNC ma chin ing cen ter as lit tle more than a glo ri fied drill press de pends upon
their ma chine ev ery bit as much as the com pany that makes com plex molds.
Actually, ei ther com pany could be underutilizing their ma chine. If a CNC ma chine is not out put ting at
its max i mum po ten tial, it is be ing underutilized. The com pany that makes molds, for ex am ple, may not
know about a help ful pro gram ver i fi ca tion sim u la tor that would al low them to ver ify their pro gram’s tool
path on a per sonal com puter be fore it is sent out to the CNC ma chine. They may be ex pe ri enc ing waste ful
down time while mis takes are found and cor rected at the ma chine dur ing setup. On the other hand, the
com pany mak ing man i folds may not be aware of how an au to matic dis trib u tive nu mer i cal con trol (DNC)
sys tem can re duce pro gram trans fer time to un der thirty sec onds. They may be wast ing time as the setup
per son walks be tween the CNC ma chine and the serv ing com puter to com mand pro gram trans fers.
1.1.1.2. Ma chine uti li za tion ver sus per son nel uti li za tion
Through out this course we place the high est em pha sis on max i miz ing CNC ma chine tool uti liza tion. And
this should be of ex treme im por tance to any CNC-using com pany. How ever, to many com pa nies i t is also
of great im por tance to get the most out of the peo ple that pro gram, setup, and op er ate their CNC ma chines. You must un der stand that when you strive to max i mize per son nel uti li za tion, ma chine uti li zation usu ally suf fers.
Think about a con tract shop that em ploys one per son to take care of each CNC ma chine the com pany
owns. In this kind of com pany, each in di vid ual must com pletely pro gram, setup, and run pro d uc tion for
ev ery job that co mes to their ma chine. It is quite likely that the CNC ma chine will sit idle for long pe ri ods
while this per son is pro gram ming and set ting up the ma chine. While the com pany is get ting the most
from its CNC peo ple, it is not com ing close to achiev ing max i mum po ten tial in ma chine uti lization.
Even many prod uct-producing com pa nies com monly at tempt to max i mize per son nel uti li za tion. And unfor tu nately, they may not be con sid er ing the im pact this has on CNC ma chine uti li za tion. Since many
man age ment peo ple can not stand to see any one sit ting idle (even while the CNC ma chines theyare running are producing), they as sign their op er a tors other du ties to per form dur ing each pro d uction run.
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When it co mes to ma chine uti li za tion, this may be just fine as long as CNC ma chines don’t sit idle while
op er a tors per form their other du ties. But in re al ity, this is dif fi cult to achieve. It is not un com mon that
CNC ma chines do of ten sit idle wait ing for the op er a tor to fin ish some sec ond ary task.
Some com pa nies even have their CNC op er a tors run ning two or more CNC ma chines. Again, they’re really get ting the most out of their CNC op er a tors. How ever, one ma chine may be con stantly sit ting idle
while the op er a tor fin ishes up with tasks on the other ma chine/s (load ing workpieces, chang ing in serts,
in spec tions, etc.).
In all ex am ples to this point, con sider the high price com pa nies are pay ing to max i mize per son nel uti li zation. The shop rate (the amount the com pany charges per hour for the CNC ma chine’s use) for a typical
CNC ma chine is usu ally at least four to ten times the wage of a CNC op er a tor, based upon the c omplexity
of the ap pli ca tion and ma chine size. From a bot tom-line stand point and given the choice, you should be
more will ing to have a CNC op er a tor sit ting idle wait ing on a CNC ma chine than a CNC ma chine sit ting
idle wait ing for a CNC op er a tor.
Some com pa nies fully ac cept the im pact that max i miz ing per son nel uti li za tion has on CNC ma chine utili za tion. In fact, it may be part of the com pany’s gen eral phi los o phy. For in stance, many com pa nies incor po rate man u fac tur ing cells. A cell may have sev eral CNC ma chine tools (pos si bly along with other
con ven tional equip ment) and may be at tended by just one per son. The pri mary goal in most manu fac turing cells is to com plete a workpiece (or pos si bly even a com plete as sem bly of sev eral workpieces) right in
the cell. This can dra mat i cally im prove the through-put of prod ucts flow ing through the company. However, it is not un com mon for one or more ma chines in the cell to be idle while other op er a tions are be ing
per formed, mean ing ma chine uti li za tion may be rather low. Since the pri or ity is im proved though-put,
the com pany will ing pays the price in lower ma chine uti li za tion.
As stated, this course will em pha size im prov ing CNC ma chine uti li za tion. Since your CNC machines’
max i mum out put is di rectly tied to how many peo ple are avail able in your CNC en vi ron ment, we will often as sume you have an ad e quate sup port staff - or at least that you are will ing to con siderchanges in the
way you cur rently uti lize your per son nel.
We want to make one last point about im prov ing CNC ma chine tool uti li za tion. There are com p a nies that
have very pre dict able pro duc tion sched ules. Many au to mo tive com pa nies, for ex am ple, know with great
pre ci sion just how many workpieces will be re quired dur ing a day, week, month, and/or year. This kind of
com pany will pur chase an ad e quate num ber of ma chines to en sure that their pro duc tion sched ule is met.
Once started, as long as there are no changes in re quired pro duc tion vol umes, there will be no need to
ever im prove ma chine uti li za tion. The vast ma jor ity of com pa nies, how ever, do not share this lux ury,
and will greatly ben e fit from im prove ments in ma chine uti li za tion. We’re as sum ing you work for one of
them.
1.1.2. Cri te ria for wise de ci sions
De ci sions that af fect your CNC uti li za tion must of course be based upon your own com pany’s best in terests. As stated, there are many expert sales peo ple in this field who can make the features of their
CNC-related prod ucts sound right for just about ev ery one. Poor de ci sions lead to mis ap pli c a tion. Mis appli ca tion leads to underutilization. Here we in tend to ex pose in or der of im por tance those fac tors that
con trib ute to mak ing wise de ci sions.
Ad mit tedly, ev ery rule has an ex cep tion. Ex cep tions fuel the fires of con tro versy and con fu sion re gard ing
your best choices. In this early pre sen ta tion, we speak in very gen eral terms. As you view this dis cus sion,
you may quickly spot some ex cep tions to what is be ing pre sented. Rest as sured that we will fur ther clarify a com pany’s spe cific needs as well as how they are best ad dressed as we look at some spe cific ex am ples.
1.1.2.1. Com pany type
There are but four types of com pa nies us ing CNC ma chine tools. Though there are some over laps, all
CNC us ers can be placed in one of these four ba sic cat e go ries.
Prod uct-producing com pa nies get their rev e nue from the sale of a prod uct. In a sense, profit is one
step re moved from man u fac tur ing since a prod uct will not even come to mar ket if the com pany can not
make a profit. Prod uct-producing com pa nies tend to have elab o rate en gi neer ing de part ments (de sign en-
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gineering, industrial en gi neer ing, man u fac tur ing en gi neer ing, process engineering, tool engineering,
qual ity con trol, etc.). All fac ets of man u fac tur ing tend to be well thought-out - and good rea sons can be
given for just about ev ery thing that is done in the CNC en vi ron ment. These com pa nies also t end to break
up the tasks re lated to CNC ma chine us age. One per son de vel ops the ma chin ing pro cess. An other per son
de signs/or ders the re lated tool ing. An other de vel ops the pro gram. An other gath ers, as sem bles, and if
nec es sary, mea sures the tool ing. An other makes the ma chine setup and runs the first workpiece. Another in spects the workpiece/s. An other com pletes the pro duc tion run. De pending upon the prod uct being man u fac tured, prod uct-producing com pa nies can have rather com pli cated CNC en vi ron men ts. If the
com po nent workpieces to be ma chined are quite di verse, it is likely that a wide va ri ety of dif fer ent CNC
ma chine types (along with con ven tional and spe cial ma chines) will be re quired to pro duce them.
Workpiece-producing com pa nies (also called con tract or job shops) get their rev e nue from the sale of
com po nent workpieces to prod uct pro duc ing com pa nies. Profit is di rectly tied to man u factur ing since
work is quoted based upon an hourly rate for machine usage. While there are exceptions, most
workpiece-producing com pa nies can not af ford to en gi neer their jobs as elab o rately as prod uct-producing
com pa nies. In fact, they must com monly make com po nent workpieces with out the ben e fit of the product-producing com pany’s help, and for less money than the prod uct-producing com pany can. This means
CNC peo ple work ing for workpiece pro duc ing com pa nies must be ex tremely re source ful and innovative.
Most tend to spe cial ize in but a few ma chin ing op er a tions, mean ing most will have fewer machine types
than prod uct-producing com pa nies. This tends to sim plify their CNC en vi ron ments. CNC peo p le working for workpiece-producing com pa nies must nor mally per form more than one func tion. It is not un common, for in stance, that one per son will com pletely pro gram, setup, and op er ate their CNC ma c hine/s for
the jobs they run.
Tooling-producing com pa nies get their rev e nue from the sale of tool ing (jigs, fix tures, dies, molds,
gauges, etc.) to prod uct-producing and workpiece-producing com pa nies. They share many at trib utes of
both prod uct-producing and workpiece-producing com pa nies. Since they ac tu ally make a prod uct (the
jig, fix ture, die, etc.) profit is com monly one step re moved from man u fac tur ing, mak ing them sim i lar to
prod uct pro duc ing com pa nies. How ever, the quan tity of tools (their prod uct) be ing pur chased is usu ally
very small. And most have lim ited re sources, mak ing them sim i lar to workpiece pro duc ing companies.
Most tool ing pro duc ing com pa nies do tend to spe cial ize in a tool ing type (jigs, fix tures, gauges, molds,
etc.), mean ing they will typ i cally have fewer ma chine types than prod uct-producing com pa nies. As with
workpiece-producing com pa nies, CNC peo ple work ing for tool ing-producing com pa nies tend to perform
sev eral tasks.
With some tool ing-producing com pa nies, the prod uct is per ish able (wears out and must be re placed on a
reg u lar ba sis). Tooling-producing com pa nies that man u fac ture cut ting tools, like car bide in serts and tool
hold ers re ally don’t fit the mold of the kind of tool ing-producing com pany as we have de fined it. Truly,
this kind of com pany is more a prod uct-producing com pany than a tool ing-producing com pany.
Prototype-producing com pa nies get their revenue from the sale of trial workpieces to product-producing companies. The method of producing prototypes may be quite conventional, in volving
CNC equip ment to make the pro to type workpiece/s. It may also in volve pro duc ing a die or mold that in
turn makes the pro to type workpiece/s. On the other hand, the method may in volve newer pro cesses (like
ste reo li thog ra phy) to pro duce the pro to types. While this di ver sity makes it is dif fi cult to make too many
gen er al iza tions, pro to type-producing com pa nies tend to share much in com mon with tool ing producing
com pa nies when it co mes to com plex ity of work, per son nel uti li za tion, pro gram ming methods, etc.
Over laps in com pany types are com mon. A prod uct pro duc ing com pany may, for ex am ple, have a tool
room (in clud ing CNC ma chines) to make their pro duc tion tool ing. And/or they may have a re search and
de vel op ment de part ment to pro duce their pro to types. On the other hand, a con tract shop that gets the
bulk of its rev e nue from the sale of com po nent workpieces may also have a prod uct of its own. Com panies
with over laps must ap ply CNC ma chines in com pletely dif fer ent ways and tend to have the most com plicated CNC en vi ron ments.
1.1.2.2. Other fac tors con trib ut ing to a com pany’s iden tity
While we have ex posed some im por tant gen er al iza tions about how a com pany op er ates based u pon company type alone, sev eral other fac tors fur ther clar ify a com pany’s true iden tity. These factors can have a
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Mod ule Num ber One
pro found ef fect on the com pany, and in some cases, will con flict with the gen er al iza tions given for company type. For in stance, a con tract shop that has over 90% re peat busi ness and can pre dict when jobs will
be re peated (many au to mo tive con tract shops have this lux ury) will share more in com mon with a product pro duc ing com pany than with a workpiece pro duc ing com pany. On the other hand, a prod uct pro ducing com pany that sees lit tle re peat busi ness will closely re sem ble a workpiece pro duc ing company.
Un for tu nately, it may be dif fi cult to gauge the pre cise im pact of one or more of these fac tors on your own
com pany’s true na ture. Worse, they may have a dif fer ent im pact on your com pany’s per for mance from
one de part ment of your com pany to an other. The more di verse your CNC en vi ron ment, the more likely
this pos si bil ity. In this pre sen ta tion, we’ll show the most im por tant fac tors in or der o f im por tance and offer pre sen ta tions re lated to how they af fect a com pany’s iden tity. We will con tinue to generalize.
Lot sizes - Al most all de ci sions made in the man u fac tur ing en vi ron ment be gin with the ques tion “How
many parts are we mak ing?”. This makes lot sizes among the most im por tant fac tors con trib uting to a
com pany’s iden tity. It can be very dif fi cult to ap pro pri ately gauge just what should be done to at tain a
good bal ance among workpiece qual ity, min i mized pro duc tion ex penses, and ef fi ciency. But the re lated
de ci sions are al most al ways based pri mar ily upon how many workpieces are be ing pro duced. The more
workpieces be ing made, for ex am ple, the eas ier it is to jus tify what ever it takes to pro duce the workpieces
as ef fi ciently as pos si ble. On the other hand, the fewer the num ber of workpieces be ing ma c hined, the
less a com pany will be will ing to do to en hance ef fi ciency. These de ci sions can mean the dif fer ence between profit and loss for a given job or prod uct.
Un for tu nately, many com pa nies must deal with a wide range of lot sizes. Lot sizes may range, for ex ample, from un der ten workpieces to well over one thou sand workpieces. To make mat ters worse, the same
CNC ma chines used to pro duce the small est lots are com monly used to pro duce the larg est lots.
Re peat busi ness - This is the amount of jobs that must be run on a CNC ma chine more than once. It is
com monly mea sured in per cent age. In a com pany that has 50% re peat busi ness, half the jobs that come
to a CNC ma chine have been run on that ma chine at least once be fore (the other half are new jobs, hav ing
never been run be fore).
An im por tant theme in this course is re lated to re peated tasks. The more you re peat a task, the eas ier it
will be to jus tify im prov ing it. With re peat busi ness, the task is the en tire job. Since many de ci sions that
af fect the elab o rate ness of the pro cess (ma chin ing pro cess, cut ting tools used, workholding setup, ef ficiency of the pro gram, etc.) will be based upon how of ten the job must be run, re peat busi ness is an extremely im por tant fac tor con trib ut ing to a com pany’s pro file.
Many prod uct pro duc ing com pa nies have very pre dict able pro duc tion vol umes. It is not uncom mon for a
prod uct pro duc ing com pany to be able to pre dict a tar get num ber of units that will be sold dur ing a year.
In deed, some work from a back log of out stand ing or ders. In this case, ev ery one in the com p any will know
pre cisely how many units of the com pany’s prod uct will be re quired dur ing the back log pe riod. Based on
hav ing known an nual quan ti ties, and in or der to avoid hav ing to in ven tory large num bers ofcom po nent
workpieces, many com pa nies have in cor po rated just-in-time prin ci ples. Most com pa nies will break up
their an nual quan ti ties into smaller lots and run them sev eral times through out the year. Asstated, the
more a task is re peated, the eas ier it will be to jus tify im prov ing it. If a com pany has pre dict able re peat
busi ness, it is rel a tively easy to jus tify the costs re lated min i miz ing the amount of time it takes to complete the job (mostly hav ing to do with re duc ing setup time). Knowing how many workpieces are needed
and how of ten jobs will be run also makes it easy to en gi neer and op ti mize all re lated pro cesses (ma chining pro cess, fix tures, cut ting tools, pro gram, etc.).
Note that some companies have quite a bit of re peat busi ness, but it is not pre dict able. Con sider the
workpiece-producing com pany that gets a job for the first time. While this job may be re peated in the future, most con tract shops will not know it at the time of the first or der. Other than sim ply be ing fa mil iar
with re peated jobs, this sce nario pro vides lit tle ad van tage for fu ture times when the job must be run.
Since so many jobs will never be re peated, most con tract shops han dle ev ery new job as if they will never
see it again.
Per cent age of new busi ness -This is sim ply the op po site of re peat busi ness. Again, for a com pany having about 50% new busi ness, about half the jobs have never been run be fore. And ap prox i mately twice
the time and ef fort is re quired to run a new job as com pared to a re peated job (one prop erly planned and
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doc u mented). Ad di tional tasks for new jobs in clude setup de sign (work hold ing and cut ting tools), program ming, doc u men ta tion prep a ra tion, pro gram ver i fi ca tion, and op ti miz ing. A highper cent age of new
jobs com bined with small lot sizes, short lead times, and short cycle times (a common sce nario for a
workpiece pro duc ing com pany) can make for a very chal leng ing CNC en vi ron ment.
Lead time - By our CNC-related def i ni tion, lead time is the amount of time from when a com pany’s CNC
peo ple know that a job must be run on a given CNC ma chine to the time when it is ac tu ally run. The
greater the amount of lead time, the eas ier it is to ad e quately pre pare to run jobs. Com panies that have
pre dict able an nual pro duc tion vol umes and break them up into a se ries of lots that are run at sched uled
times through out the year tend to have the lon gest lead times (nor mally prod uct-producing com p anies).
On the other hand, it is not un com mon in a workpiece pro duc ing com pany to have an or der come in the
morn ing that must be shipped that same day.
Hav ing lon ger lead times also al lows the peo ple sched ul ing jobs for a given CNC ma chine to plan the order of jobs in a way that min i mizes time and ef fort for the setup per son. If, for ex am ple, all jobs re quir ing
the eight inch ta ble vise can be run se quen tially, the setup per son can keep the workholding setup from
job to job, min i miz ing setup time.
Note that some com pa nies de sign their en tire CNC en vi ron ment for fast turn-around. Con sider, for exam ple, a tool ing-producing com pany that makes spe cial tool ing. If their cus tom ers can’t get a given tool
quickly enough, they’ll go else where. While this may be an ex treme con di tion, all com pa nies are concerned with pro vid ing their prod ucts as quickly as pos si ble - mak ing short ened lead time an important
fac tor in ev ery CNC en vi ron ment.
Typical setup time - By our def i ni tion, setup time is the amount of time it takes to go from mak ing the
last workpiece in the pre vi ous pro duc tion run to mak ing the first good workpiece (ef fi ciently) in the next
pro duc tion run. Truly, the en tire length of time the ma chine is down be tween pro duc tion runs is setup
time.
Setup time will, of course, af fect the through-put time for a job to flow through the CNC en vi ron ment, and
for this rea son, all com pa nies are highly con cerned with min i miz ing setup time. For com panies that have
pre dict able an nual pro duc tion vol umes and break them into smaller lots that are run sev eral times a
year, set ups are re peated on a reg u lar ba sis. This makes it rel a tively easy to jus tify doing what ever it
takes to min i mize setup time. On the other hand, com pa nies that have a high per cent age of new jobs will
al ways be mak ing new set ups - set ups that will not be re peated. This makes it very dif fi cult to jus tify doing things that will min i mize setup time for a given job. In stead, this kind of com pany will be look ing for
ways to stream line re peated tasks in volved with set ups (tool as sem bly, tool mea sure ment, off set en try,
pro gram zero as sign ment, etc.).
Note that since re duc ing setup time is so very im por tant to al most all CNC-using com pa nies, we de vote
an en tire mod ule of this course to setup time re duc tion.
Typ i cal cy cle time - There are two im por tant def i ni tions for cy cle time. One pop u lar def i ni tion goes like
this: “Cy cle time is the in ter val that passes from a given event in one cy cle to the same event in the next cycle.” Most peo ple use the press ing of the cy cle start but ton as the event. A per son mea sur ing cy cle time in
this man ner will start a stop watch at the in stant the op er a tor presses the cy cle start but ton. The CNC cycle will run. At its com ple tion, the op er a tor will re move the workpiece just ma chined and load the next
one. As they press the cy cle start but ton again, the timer would stop the stop watch.
While this is an im por tant cy cle time def i ni tion, it is rather sim plis tic. It does not take into con sid er ation
things that don’t hap pen dur ing ev ery cy cle (tool main te nance, sam pling in spec tions, per sonal time, etc.)
that add to the length of time it takes to com plete the pro duc tion run. If, for ex am ple, you have a 1,000
workpiece pro duc tion run and a cy cle-start-to-cycle-start time of 1 min ute, you won’t com plete the pro duc tion run in 1,000 min utes do to these ad di tional tasks. A more re al is tic def i ni tion of cy cle time is: “Cycle time is the total length of time it takes to complete the production run divided by the number of
workpieces pro duced.”
This fac tor tends to vary widely even within a given com pany for a spe cific CNC ma chine tool. Though
this is the case, it is some times pos si ble to de ter mine an av er age time. In many com pa nies, for in stance,
the typ i cal cy cle time for two axis turn ing cen ters is in the neigh bor hood of 4-5 min utes. The lon ger the
cy cle time, of course, the more likely it is that the CNC op er a tor can be do ing other things (run ning mul ti-
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Re view of Basics
Mod ule two
2.1. Re view of CNC Ba sics
This mod ule is made up of two discussions. In this discussion, we’ll re view pro gram ming-related concepts. Then we’ll re view setup- and op er a tion-related con cepts. We urge you to view this mod ule even if
you have ex ten sive CNC ex pe ri ence for three rea sons. First, you may have learned most of what you
know by attending basic courses conducted by machine tool builders or technical schools. In these
courses, in struc tors com monly show but one way that can be used to han dle a CNC func tion. In ad di tion,
you won’t have any idea of which func tions and fea tures of CNC even have al ter na tive us age techniques.
Here we will place the great est em pha sis on those CNC fea tures that can be ap plied in mul ti p le ways,
even in their ba sic forms.
Sec ond, you may be (for the most part) self-taught. If so, you’ve prob a bly had to come up with ways to
han dle CNC prob lems com pletely on your own. While you may be quite proud of the meth ods you’ve devel oped, you should at least agree that you may have missed some thing quite im por tant when it c o mes to
the ba sics. This quick re view may fill in some blanks.
And third, this mod ule will lay the ground work for the next mod ule (ad vanced im pli ca tions of ba sic features). You may be sur prised at how many seem ingly ba sic fea tures can be ap plied in ad vanced ways.
And fi nally, you may have ex ten sive com puter aided man u fac tur ing (CAM) sys tem ex pe ri ence, but limited man ual pro gram ming ex pe ri ence. Some of the best ways to im prove CNC uti li za tion require a good
com mand of man ual pro gram ming. Here, we’ll be re view ing G code level man ual pro gram ming.
Note that this mod ule is in tended to be only a re view. If you have CNC ex pe ri ence, you should find the
ma te rial quite fa mil iar and easy to un der stand. If you find that much of this in for ma tion is new to you, it
should be taken as a sig nal that you need to go back and learn more about the ba sics of CNC (note that we
of fer self study man u als to help you learn both ma chin ing cen ter and turn ing cen ter pro gram ming, setup,
and op er a tion).
2.1.1. The key con cepts ap proach
With our teach ing meth ods, there are ten key con cepts re lated to CNC ma chine us age. And the same ten
key con cepts can be ap plied to any kind of CNC ma chine tool, in clud ing ma chin ing cen ters and turn ing
cen ters. Six of the key con cepts are re lated to pro gram ming, and we’ll re view them first. Four of the key
con cepts are re lated to setup and op er a tion.
For each key con cept, we’ll first pres ent gen er al iza tions that ap ply to all kinds of CNC machine tools.
Then we’ll show how the key con cept ap plies spe cif i cally to ma chin ing cen ters. Finally, we’ll show how it
ap plies to turn ing cen ters. Here is a list of the ten key con cepts.
Programming-related:
1) Know your ma chine from a pro gram mer’s view point
2) Pre pare to write pro grams
3) You must un der stand the three most ba sic mo tion types
4) You must un der stand the com pen sa tion types
5) Pro grams must be struc tured with a strict for mat
6) Spe cial pro gram ming fea tures
Setup- and op er a tion-related:
7) Know your ma chine from an op er a tor’s view point
8) Un der stand the three modes of op er a tion
9) Know the most im por tant op er a tion pro ce dures
10) Ver ifying pro grams safely
Admittedly, determining the difference between basic techniques and more advanced techniques is
rather sub jec tive. We’ll only be in clud ing top ics in this re view that are com monly ad dressed in typ i cal basic CNC courses.
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Mod ule Num ber Two
Re view of pro gram ming ba sics
The kind of pro gram ming we’re re view ing is man ual pro gram ming (also called G code level programming). While com puter aided man u fac tur ing (CAM) sys tems au to mate much of the pro gram ming process, many of the ad vanced tech niques we show later can not be im ple mented (at least not eas ily) with
CAM sys tems and must be han dled at G code level. This means you must un der stand man ual pro gram ming if you are to get the most out of this course.
2.1.2. Key con cept num ber one - Know your ma chine from a pro gram mer’s view point
It is from two dis tinctly dif fer ent view points that you must un der stand a CNC ma chine if you are to completely mas ter its us age. Here in key con cept num ber one, we dis cuss the ma chine from a programmer’s
per spec tive. Later, in key con cept num ber seven, we’ll dis cuss the ma chine from an op er a tor’s per spective.
This key con cept ac tu ally in cludes seven top ics:
1) The im por tance of ba sic ma chin ing prac tice
2) Ma chine con fig u ra tions
3) Gen eral flow of the pro gram ming pro cess
4) Vi su al izing the ex e cu tion of a CNC pro gram
5) Un der stand ing pro gram zero
6) De ter mining the pro gram zero as sign ment val ues
7) The two ways to as sign pro gram zero
Some of these top ics are quite sim ple, and we’ll barely men tion them. Oth ers have more dra matic im plica tions, es pe cially for ef fi cient ma chine us age - and we’ll elab o rate.
2.1.2.1. The im por tance of ba sic ma chin ing prac tice
This point can not be over stressed: The more you know about ba sic ma chin ing prac tice as it relates to the
kind of ma chine you’re work ing with, the better use of the ma chine you can make. This is why ma chinists
make the best pro gram mers. A good ma chin ist knows what they want the ma chine to do. It willbe a simple mat ter of trans lat ing this into a lan guage the CNC ma chine can un der stand.
We also can not over stress the dra matic im pact your ma chin ing prac tices will have on qual ity, ef fi ciency,
safety, and just about ev ery other is sue re lated to the man u fac tur ing en vi ron ment. While ba sic ma chining prac tice is be yond the scope of this course, al most all com pa nies can ben e fit from im prove ments in
their un der stand ing of ma chin ing meth ods. It should go with out say ing that your CNC peo ple should
keep abreast of cur rent trends in cut ting tools, machinability is sues, workholding de vices, and ap pro priate pro cess ing.
One sim ple ex am ple that stresses how CNC peo ple can ben e fit from a better un der stand ing of ba sic machin ing prac tices has to do with mill ing tech niques. Con sider a ma chin ist who has only run knee-style
mill ing ma chines. As you know, a knee-style mill ing ma chine does not have nearly the ri gid ity that a bed
style mill ing ma chine has. This ma chin ist would (cor rectly) say that you must be very care ful to en sure
that all mill ing be done in a con ven tional mill ing man ner. They would say that it would be a nasty mistake to climb mill. (With most knee style mill ing ma chines, in clud ing knee-style CNC mill ing machines,
the mill ing cut ter will pull it self along the cut since the ma chine’s way sys tem usu ally has some backlash.)
If this ma chin ist’s ex pe ri ence is lim ited to knee style mill ing ma chines, they may in cor r ectly ap ply this
think ing to all forms of mill ing ma chines, in clud ing bed style ma chines. When the ma chine h as ad e quate
ri gid ity and sup port to al low climb mill ing, most ex pe ri enced ma chin ists would agree that it is wiser to
climb mill, es pe cially for fin ish ing op er a tions (though many CNC peo ple climb mill for rough ing op er ations as well). Gen erally speak ing, climb mill ing pro vides a better fin ish with less tool wear than con ventional mill ing.
Our main point is that many ma chin ists tend to get a lit tle com pla cent when it co mes to ba sic ma chin ing
prac tice. They tend to stick with ways to ma chine workpieces that they know will work. While this may
sound good, consider the machinist from the knee style milling machine example. When this person
changes to a bed style ma chine, it’s likely that they will con tinue to un wit tingly con ven tional mill, be ing
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Re view of Basics
un aware of the ben e fits that climb mill ing can pro vide. They will be more than a lit tle surprised when
they learn that, not only will climb mill ing work, that it will be the pre ferred mill ing method.
Note that through out this course we as sume your ma chin ing pro cesses are ap pro pri ate to your needs.
We will be of fer ing sug ges tions for im prove ments based upon your cur rent meth ods.
When it co mes to ma chin ing cen ter us age, com mon ma chin ing op er a tions in clude hole ma chin ing op er ations like cen ter drill ing, spot drill ing, drill ing, tap ping, ream ing, and bor ing - as well as mill ing op er ations like face milling and contour milling. When it comes to turning centers, common machining
op er a tions in clude rough turn ing, rough bor ing, rough fac ing, fin ish turn ing, fin ish boring, fin ish fac ing,
thread ing, neck ing, and knurl ing. And since al most all cur rent model ma chin ing cen ters and turn ing
cen ters can hold mul ti ple tools that can be au to mat i cally se lected from within the pro gram, the ma chining or der (pro cess) is of par a mount im por tance to the suc cess of the CNC pro gram. Gen erally speak ing,
even a poorly de vel oped CNC pro gram can be even tu ally made to work if the pro cess is good. But even a
per fectly writ ten CNC pro gram (one that does ex actly what the pro gram mer in tends) will fail if the process is bad.
2.1.2.2. Ma chining cen ter con fig u ra tions
While a CNC user does not have to be a ma chine de signer, it is help ful if pro gram mers, setup peo ple, and
op er a tors know the ba sic com po nents mak ing up the CNC ma chine tools they’ll be work ing with. For the
pur pose of our dis cus sions, the de vice that sep a rates CNC ma chin ing cen ters from CNC milling ma chines is the au to matic tool changer. This de vice al lows the ma chine to store sev eral tools within the machine’s tool magazine and au tomatically change tools during the program’s execution. This means
ma chin ing cen ters are multi-tool ma chines and can per form a mul ti tude of ma chin ing op er a tions on the
workpiece dur ing the CNC cy cle.
Ma chining cen ters are avail able in a va ri ety of styles, but are most ba si cally clas si fied based upon the orien ta tion of the spin dle. If the spin dle is in a ver ti cal at ti tude it is re ferred to as aver ti cal ma chin ing center. If it is in a hor i zon tal at ti tude, it is called a hor i zon tal ma chin ing cen ter.
Ma chine tool build ers vary dra mat i cally when it co mes to ma chine de sign. Within the ver ti cal ma chin ing
cen ter clas si fi ca tion, for ex am ple, there are three ba sic styles - knee style, C-frame style (also called bed
style), and gan try style (also called bridge style). Ma jor com po nents mak ing up a spe cific C NC ma chin ing
cen ter in clude base (or bed), col umn, spin dle, ways, au to matic tool changer sys tem, and the CNC con trol.
Ma jor spec i fi ca tions that CNC us ers tend to be most in ter ested in in clude axis trav els, m ax i mum spin dle
speed, rapid rate, max i mum feedrate, max i mum weight of workholding setup, tool change time, max imum tool weight, and con trol style.
Based upon these vari a tions (and oth ers), de cid ing which CNC ma chin ing cen ter will be best suited to a
given ap pli ca tion is no easy task. We’re as sum ing through out this course that you have ap pro pri ate machines for your ap pli ca tions. Mis takes in this re gard will, of course, lead to se vere underutilization. Common mis takes in clude: 1) Pur chasing a ver ti cal ma chin ing cen ter when a hor i zon tal is better suited for
the ap pli ca tion. 2) Pur chasing ma chines with ul tra-high spin dle speeds (over 10,000 rpm) when the machine will be used pri mar ily to ma chine harder ma te ri als like steel (most of these ma chineswill have no
power at low spin dle speeds). 3) Pur chasing ma chines with lower spin dle speeds when only light duty machining is required. 4) Mistakes in way construction selection. Again, mis ap pli ca tion leads to
underutilization.
1. Ma chining cen ter di rec tions of mo tion
All ma chin ing cen ters have at least three lin ear axes named X, Y, and Z. With ver ti cal ma chin ing cen ters
and as view from the front of the ma chine, the left/right di rec tion of mo tion is the X axis. The fore/aft direc tion of mo tion is the Y axis. Up/down is the Z axis. The mov ing com po nent of the axis var ies with machine de sign. With knee style ma chines, the mov ing com po nent for the X and Y axes is the ta b le. The
mov ing com po nent for the Z axis is com monly the quill (though it could be the knee). With C-frame style
ver ti cal ma chin ing cen ters, the mov ing com po nent for the X and Y axes is still the ta ble. The mov ing compo nent for the Z axis is the headstock. With gan try style ver ti cal ma chin ing cen ters, the h eadstock is the
mov ing com po nent for the X and Y axes (tool moves along with the axes). The quill is the mov ing com ponent for the Z axis.
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Mod ule Num ber Two
With hor i zon tal ma chin ing cen ters, and as viewed from the front of the ma chine, the left/right mo tion direc tion (most com monly ta ble mo tion) is the X axis. The up/down mo tion of the headstock is the Y axis.
The fore/aft mo tion di rec tion (com monly ta ble mo tion) is the Z axis.
Many ma chin ing cen ters have ad di tional (ro tary) axes. If placed upon the ta ble of a ver tical ma chin ing
cen ter, an ad di tional ro tary axes could be named A, B, or C, de pend ing upon its ori en ta tion with the machine. If placed in the ta ble mech a nism of a hor i zon tal ma chin ing cen ter (ta ble ro tates), it is called the B
axis.
Ev ery axis has a po lar ity (plus ver sus mi nus di rec tion) With the ver ti cal ma chin ing center de picted, the
ta ble moves to form the X and Y axis and the headstock moves to form the Z axis. Note that the headstock
in cludes the spin dle that ac tu ally holds the cut ting tool. For this kind of ma chine, the polar ity (plus versus mi nus) of the Z axis is very easy to un der stand. As the tool (headstock) moves closer to the ta ble top
(down), the Z axis is mov ing in the mi nus di rec tion. As it moves away from the ta ble top (up), it is mov ing
in the plus di rec tion.
How ever, with the X and Y axes (for this style of ma chine), the cut ting tool does not ac tu ally move with
the axis. In stead, the ta ble moves. This makes un der stand ing the axis po lar ity a lit tle more dif fi cult.
When con sid er ing axis po lar ity from the pro gram mer’s view point, it is al ways best to think of axis po larity as if the tool is mov ing. In or der for the tool to move in the plus di rec tion (to the right), the ta ble must
move to the left.
Note that gan try ver ti cal ma chin ing cen ters in cor po rate trav el ing col umns to form the mo tion of the X
and Y axes. For these ma chines, un der stand ing axis po lar ity is eas ier since the tool is actu ally mov ing
with the axis. When ever the tool is sta tion ary dur ing an axis move ment, the axis po lar ity will be a lit tle
con fus ing. This is true of any kind of CNC ma chine tool, in clud ing ver ti cal as well as hori zon tal ma chining cen ters.
2.
Ma chining cen ter pro gram ma ble func tions
To day’s full blown ma chin ing cen ters al low the pro gram mer to con trol just about any func tion re quired
through programmed commands. Here we list the things that the programmer can usually control
within the pro gram and give a cur sory view of how each func tion is pro grammed.
Spin dle speed - A pro gram mer can con trol pre cisely how fast the spin dle ro tates in one RPM i ncrements.
An S word is used for this pur pose. If the pro gram mer wishes 350 RPM, the word S350 is com manded.
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Re view of Basics
Spin dle di rec tion - A pro gram mer can con trol which di rec tion the spin dle ro tates, for ward or re verse.
The for ward di rec tion is com monly used for right hand tool ing and the re verse di rec tion is used for left
hand tool ing. Two M codes con trol this func tion. An M03 turns the spin dle on in the for ward direction.
M04 turns the spin dle on in a re verse di rec tion.
Spin dle range - Most larger ma chin ing cen ters have more than one spin dle range. Like the gear shift lever in an au to mo bile, the low spin dle range will be used for slow speed and pow er ful ma chining. The high
spin dle range will be used for faster speed with less power avail able.
The se lec tion of the spin dle range can be some what trans par ent to the pro gram mer. With most ma chines, the spin dle speed word (S) helps the con trol to se lect the re quired spin dle range. If the spin dle
speed is in the low range, the con trol will au to mat i cally se lect the low range prior to turning the spin dle
on. If the speed is in the high range, the con trol will au to mat i cally se lect the high range prior to the spindle start.
Say, for ex am ple, your ma chin ing cen ter’s low range runs from 20 to 1500 RPM. The ma chine’s high
range runs from 1501 to 3500 RPM. If you com mand a speed of S500, the con trol will au to mat i c ally se lect
the low range. If you com mand a speed of S2000, the con trol will au to mat i cally se lect the high range.
Feedrate - A pro gram mer can con trol the mo tion rate for any ma chin ing op er a tion. This isdone with an F
word. The F word spec i fies feedrate in per min ute mode. If you wish to work in the inch sys tem, this
feedrate will be in inches per min ute. If you work in the met ric, the feedrate will be in mil li me ters per
min ute. A feedrate of 3.5 IPM would be pro grammed as F3.5 in the inch mode.
Cool ant - A pro gram mer can turn cool ant on and off at any time from within a pro 0000gram. An M08
com mand turns (flood) cool ant on and an M09 turns the cool ant off.
Tool changes - All ma chin ing cen ters have au to matic tool chang ers that al low tools to be loaded into the
spin dle au to mat i cally dur ing the pro gram’s cy cle. This, of course, al lows a mul ti tude o f ma chin ing op er ations to be per formed within one pro gram cy cle.
Though this func tion will change slightly from one ma chin ing cen ter to an other, many ma chin ing cen ters
use a T word to ro tate the ma chine’s tool mag a zine to the de sired po si tion. For ex am ple,a T05 ro tates the
mag a zine to sta tion num ber five (sta tion five is in the ready po si tion). An M06 com mand is used to ac tually make the tool change and ex changes the tool in the ready po si tion with the tool in the spin dle. Assuming the ma chine is at its tool change po si tion, the com mand T05 M06 will place tool num ber five in the
spindle.
What else might be pro gram ma ble? - While have ac quainted you with the most com mon pro gram mable
func tions of ma chin ing cen ters, you must be pre pared for oth ers. Other fea tures that may be equipped on
your own ma chines in clude pal let chang ers, pro gram ma ble chip con vey ers, spin dle probes, tool length
mea sur ing probes, and a va ri ety of other ap pli ca tion based fea tures.
2.1.2.3. Turn ing cen ter con fig u ra tions
All CNC turn ing cen ters have at least two (lin ear) axes. And for the most pop u lar style of CNC turn ing
cen ter, the tool (held in a tur ret) moves along with each axes. The X axis is the di am e ter-controlling axis.
It is the di rec tion of mo tion per pen dic u lar to the spin dle cen ter line. For al most all cur rent model turn ing
cen ters, X is spec i fied in di am e ter. If turn ing a 2.5 in di am e ter, for ex am ple, this X axis po si tion is spec ified as X2.5. The Z axis is the length-controlling axis. It is the di rec tion of mo tion par allel to the spin dle
centerline.
Each axis has a po lar ity (plus ver sus mi nus di rec tion). For al most all ma chines, the X minus di rec tion is
mo tion to ward the spin dle cen ter, get ting smaller in di am e ter. X plus is the mo tion away from the spindle cen ter, get ting big ger in di am e ter. (We do know of two turn ing cen ter man u fac tures that re verse the
po lar ity for the X axis.) Z mi nus is mo tion to ward the work hold ing de vice (chuck). Z plus is the di rec tion
of mo tion away from the work hold ing de vice. The draw ing shows these two axes as well as po lar ity for
the most pop u lar form of turn ing cen ter.
Note that al most all cur rent model turn ing cen ters ad here to these stan dards for the X and Z axis. This
makes pro gram ming for dif fer ent types of tun ing cen ters quite sim i lar. Though the con figu ra tions may
ap pear rad i cally dif fer ent from one an other, the same two-axis pro gram could be loaded and cor rectly run
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Mod ule Num ber Two
in any of the ma chines. (X is al ways the di am e ter-controlling axis and Z is al ways the length con trol ling
axis.)
De pending on their ap pli ca tion, some turn ing cen ters are equipped with a third (ro tary) axis mounted
within the headstock. This axis is named the C axis. When a turn ing cen ter has a C axis, it will al ways be
equipped with live tool ing as well. This means the turn ing cen ter can ac tu ally ro tate cut ting tools (like
drills, taps, ream ers, and end-mills) that are held in the tur ret.
C axis and live tool ing al low the CNC user to per form op er a tions not com monly as so ci ated with turn ing
cen ters. With these fea tures, sec ond ary op er a tions that would nor mally have to be done after the turn ing
cen ter op er a tion can be done right in the turn ing cen ter. This min i mizes the num ber of op er a tions it will
take to com pletely ma chine a workpiece.
The C axis can be used to ro tate the workpiece to a pre cise an gu lar po si tion. The live tool (drill, reamer,
tap, etc.) can then be used to ma chine cross holes (par al lel to the X axis) or through holes (par al lel to the Z
axis). The C axis can even ro tate dur ing ma chin ing, and when equipped with a spe cial mo tion type called
po lar co or di nate in ter po la tion, the CNC user can even use a mill ing cut ter to ma chine elab o rate con tours
in the out side di am e ter of the workpiece (com bin ing X and C axis mo tions). When a turn ing cen ter has a
C axis with live tool ing, it’s al most like hav ing a ma chin ing cen ter (or mill ing ma chine) b uilt right into the
turn ing cen ter.
One se vere lim i ta tion of the three axis turn ing cen ter (X, Y, and C) is that the cut ting tool can only move
in one plane (the X-Z plane). This lim its what can be done with mill ing cut ters. For this reason, some
turn ing cen ter man u fac tur ers equip their live tool ing turn ing cen ters with an axis that al lows the tur ret
to move per pen dic u lar to the X-Z plane. This axis is called the Y axis. When equipped with a Y axis, the
turn ing cen ter truly is very much like a mill ing ma chine or ma chin ing cen ter.
The uni ver sal slant bed turn ing cen ter
This is the most com mon form of CNC turn ing cen ter. By far, this con fig u ra tion out-numbers any of the
other forms. This form of turn ing cen ter is so pop u lar be cause all ma jor ap pli ca tions for turn ing can be
ac com plished, in clud ing shaft work (by us ing the tailstock), chuck ing work, and bar work (if a bar feeder
is used).
Uni ver sal style slant bed turn ing cen ter (axis po lar ity re flects tur ret mo tion)
Note that most other turn ing cen ter con fig u ra tions are sim ply off-shoots of the uni ver salstyle slant bed
turning center. A chucking style turning center, for example, is identical, except it does not have a
tailstock (shaft work can not be per formed). A ver ti cal style turn ing cen ter has the spin dle ori ented in a
ver ti cal at ti tude (X is still the di am e ter-controlling axis and Z is still the length-controlling axis). Twin
spin dle turn ing cen ters (both slant bed and ver ti cal) have the abil ity to run two pro grams at once and can
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Ba sic Fea tures That Have Ad vanced Implications
Mod ule three
3.1. Basic CNC fea tures with ad vanced im pli ca tions
There are count less ways to han dle even the most ba sic of CNC fea tures. But it’s likely that i n most ba sic
CNC courses you’ve at tended, you’ve been ex posed to but the most ru di men tary ways to han dle CNC
func tions. Again, the pri mary (and some times the only) ob jec tive of most ba sic CNC courses it to get students to the point that they can be gin work ing with their CNC ma chines. Given the amount of new in forma tion pre sented in ba sic CNC courses, en try level stu dents may not be ready for much more atthis early
stage of their de vel op ment.
Once a stu dent gains ex pe ri ence with the CNC ma chine/s, they will be come fa mil iar and con f i dent with
the meth ods they reg u larly use. In quis i tive nov ices will soon be gin to won der about other tech niques
(those not taught in ba sic courses) that will en hance their gen eral un der stand ing of CNC.
In this mod ule, we’ll ex pose you to many tech niques that are not com monly taught in ba sic CNCcourses.
How ever, we will limit our pre sen ta tion in this mod ule to in clude only rel a tively ba sic CNC fea tures that
are in tro duced in ba sic CNC courses. You may be sur prised at how many ba sic fea tures do have mul ti ple
uses. We’re call ing any sec ond ary use that is not pre sented in a typ i cal ba sic course an ad vanced im pli cation.
Ad mit tedly, many of the func tions we show are still pretty ba sic. The more time you’ve spent around
CNC ma chines, the more likely it is that you’ve come across some of the tech niques we show. This mod ule
will be of most ben e fit to stu dents that have been ex posed to the ba sics, but have but a lim ited amount of
ac tual CNC ex pe ri ence (three months to one year). Though this is the case, even highly ex pe r i enced CNC
peo ple will likely find many of the tech niques we show in this mod ule to be new and unique.
The or ga ni za tion of this mod ule (and most to come) is ref er ence in na ture. When it co mes to CNC program ming words, for ex am ple, we’ll be pre sent ing this ma te rial by word or der in CNC com mands as follows.
Mes sage (pa ren the ses) tech niques
Slash code (/) tech niques
N word tech niques
G word tech niques (ad dress ing G codes in nu mer i cal or der)
Axis spec i fi ca tion tech niques
Spin dle speed tech niques
Feedrate tech niques
T word tech niques
M word tech niques (ad dress ing M codes in nu mer i cal or der)
Com pare this ref er ence method to the highly tu to rial method by which mod ule two (re view of ba sics) is
pre sented. While the pre sen ta tion for each in di vid ual tech nique will be as tu to rial as w e can make it, the
gen eral or der of pre sen ta tion will have no log i cal or tu to rial flow.
3.1.1. Un der stand ing pa ram e ters
All CNC us ers will even tu ally have to be come fa mil iar with pa ram e ters. Though they are not even mentioned in most ba sic CNC courses, and though most CNC peo ple would agree that the con trol of param eters is more the re spon si bil ity of a ser vice or main te nance per son than a CNC pro gram mer, setup per son,
or op er a tor, there are many pa ram e ters that af fect the way CNC pro grams are ex e cuted. Ev ery CNC person should, at the very least, be aware of their ex is tence. Better yet, they should be on the con stant lookout for ma chine be hav ior that is af fected by pa ram e ter set tings.
Again, parameters affect the way the CNC machine behaves. And throughout this module, indeed
through out the rest of this course, we will men tion many ma chine and con trol func tions that are af fected
by them. There are two ba sic types of pa ram e ters.
Like tool off sets, all pa ram e ters are num bered and pa ram e ters are al ways re ferred to by their num bers.
With most con trols, there are well over one thou sand pa ram e ter func tions.
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Mod ule num ber three
3.1.1.1. Eight bit bi nary type
Each eight bit pa ram e ter con trols up to eight in di vid ual func tions. Each digit of the pa r am e ter is called a
bit. The bit num ber ing is a lit tle un usual, and fol lows bi nary struc ture. The right most bit is bit num ber
zero and num bers as cend from right to left. The left most bit is bit num ber seven. (Note that bit num ber
five is the sixth bit from the right.) The draw ing shows an ex am ple.
201: Transfer condition
NCR
ASC SB2
00000011
7
6
5
4
3
2
1
0
NCR 0: The EOB code used in output is LF, CR, CR
1: LF only
ASC 0: The code used for data output is ISO
1: ASCII
SB2 0: The number of stop bits is one
1: two
Draw ing of eight bit bi nary pa ram e ter
Each bit of this pa ram e ter type will con trol an in di vid ual func tion, and con tains a zero or a one. Zero is
used to rep re sent off, no, or some neg a tive con di tion. One is used to rep re sent on, yes, or some pos i tive
con di tion. The pa ram e ter doc u men ta tion will com monly use three char ac ter ab bre vi a tions for each bit
name and spec ify ex actly what will hap pen if the bit is set to a one or a zero.
3.1.1.2. Whole num ber type
Many pa ram e ters need to spec ify more than but one of two pos si bil i ties (0 or 1). They will con tain ac tual
val ues. One turn ing cen ter pa ram e ter, for ex am ple, spec i fies the min i mum depth of cut for the G76
thread ing cy cle.
Note that most do not al low dec i mal points to be in cluded in the pa ram e ter’s value, so a fixed for mat must
be used for dec i mal en tries. If work ing with a four place dec i mal for mat, for ex am ple, the value 0050 will
be 0.005 inch.
3.1.1.3. Im por tance of back ing up pa ram e ters
Pa ram e ters are vol a tile. Like CNC pro grams and tool off sets, they are backed up by a bat tery when the
power is turned off. But the day will even tu ally come when the bat tery will go dead. Most controls will
sound an alarm as the bat tery starts to de te ri o rate, but you must be pre pared for the worst. If the machine is off for a long pe riod of time with a fail ing bat tery, it is pos si ble that you will not get any warn ing
prior to the bat tery fail ing. Any data re tained by the bat tery (in clud ing pa ram e ters) will be lost!
All cur rent model con trols al low you to back up your pa ram e ters us ing stan dard dis trib u tive nu mer i cal
con trol (DNC) de vices, us ing the same tech niques you do for trans fer ring CNC pro grams. Consult your
con trol man u fac turer’s op er a tion man ual to find the pro ce dure to back up pa ram e ters.
We can not over stress the im por tance of main tain ing a backup copy of pa ram e ters. Ac cord ing to Fanuc
USA, the larg est sin gle source of ma chine down time is when a ma chine fail ure oc curs that causes pa rame ters to be lost, yet the CNC user has not main tained a backup copy of pa ram e ters. Much time is wasted
while trial-and-error tech niques are used to man u ally en ter pa ram e ter data. BE SURE TO BACK UP
YOUR PA RAM E TERS! Also re mem ber to up date your backup copy when you make pa ram e ter changes.
Page 3-2
CNC Concepts, Inc.
As the CNC user, you - and you alone - are re spon si ble for main tain ing the backup copy of your pa ram eters.
3.1.2. Doc u menting in the pro gram
You prob a bly know that al most all cur rent model CNC con trols al low you to in clude mes sages within
your CNC pro grams for doc u men ta tion pur poses (though many ba sic CNC course don’t even men tion
them). Even if this fea ture is in tro duced in the ba sic CNC course, most in struc tors will not de scribe the
var i ous times when doc u ment ing mes sages should be used.
Fanuc and Fanuc-compatible con trols use pa ren the ses [()], which are also called con trol in and out, for
the pur pose of in clud ing mes sages in the pro gram. When the con trol reads a left pa ren the sis, it ig nores
any text it sees un til it co mes to a right pa ren the sis. At this point it con tin ues ac tu ally ex e cut ing the
words and com mands it sees in the pro gram. While some con trols al low both up per and lower case charac ters, most Fanuc and most Fanuc-compatible con trols re quire that the mes sage in cluded within the paren the ses be in up per case (all cap i tal let ters).
Some con trols use dif fer ent char ac ters to des ig nate that mes sages are be ing given (some use a dollar
sign, for ex am ple). Re gard less of how mes sages are la beled, al most all cur rent model CNC con trols al low
some way for the pro gram mer to in clude doc u ment ing mes sages right in the CNC pro gram that will appear on the dis play screen when the setup per son or op er a tor views the pro gram.
Older con trols may not have the abil ity to ac tu ally dis play mes sages on the dis play screen, but at least
they can be in cluded on the pro gram’s print out (hard copy). Also note that some con trols do have the ability to dis play mes sages on the dis play screen but do not have the pa ren the ses char ac ters (or all let ters of
the al pha bet) on the con trol panel key board. For this kind of con trol, mes sages can not be en tered or modi fied at the ma chine.
You will no tice that just about ev ery com mand of ev ery ex am ple pro gram given in this text will have a
mes sage within pa ren the ses to help you un der stand what is go ing on within the com mand. Admittedly,
our us age of mes sages is ex treme (doc u ment ing ev ery com mand) and we do not rec om mend that you do
so. While this fea ture is not at all ad vanced, many pro gram mers do not use this fea ture to document
nearly as ex ten sively as they should. In this dis cus sion, we in tend to ex poses the most im p or tant ap pli cations for in clud ing mes sages in CNC pro grams.
3.1.2.1. Pro gram head ers
A well doc u mented CNC pro gram be gins with a se ries of mes sages that re move any doubt about the program’s use. Here is a sam ple pro gram be gin ning that in cludes suf fi cient doc u men ta tion for this pur pose.
O0001
(*** PRO GRAM QUAL IFIED 2/12/99 ***)
(
MA CHINE: MORI SEIKE SL4)
( PART NUMBER: A-2355-2C)
(
PART NAME: BEARING FLANGE)
(
RE VI SION: F)
(
(
CUS TOMER: ABC COM PANY)
OP ER A TION: 20, MA CHINE BORED END OF PART)
( PRO GRAMMER: MLL)
(DATE FIRST RUN: 4/11/98)
(PRO GRAM RE VI SION: C)
( LAST PRO GRAM RE VI SION: 1/30/98 BY CRD)
(
RUN TIME: 00:05:25)
N005 T0101 M41
N010 G96 S400 M03
CNC Concepts, Inc.
Page 3-3
N015 G00 X3. Z.1 M08
.
.
.
No tice that any one view ing this header in for ma tion can eas ily tell which CNC ma chine the pro gram is
for, the workpiece and op er a tion the pro gram is ma chin ing, who wrote the pro gram, who last changed it,
and three im por tant dates. Though this kind of in for ma tion may seem quite ba sic, re mem ber that many
com pa nies even tu ally ac cu mu late thou sands of CNC pro grams. With out this ba sic doc u men tation in
each pro gram, it can be next to im pos si ble to keep track of which pro grams are used for a given job.
No tice that the first doc u ment ing line deals with whether the pro gram is qual i fied, or proven. When they
have many re peated jobs, most com pa nies strive to min i mize the num ber of changes re quired af ter the
job is first run. In deed, many com pa nies do not al low their setup peo ple and op er a tors to mod ify what
they con sider to be qual i fied or proven pro grams with out get ting the ap proval of the CNC programmer.
This mes sage spec i fies to the op er a tor that the pro gram is qual i fied, and should run without the need for
modification.
Also of im por tance in our ex am ple header are the cur rent re vi sions for workpiece and pro gra m. Re member that the de signs for pro duc tion workpieces are com monly changed, mean ing changes in CNC pro grams. These changes can wreak havoc with the or ga ni za tion and main te nance of CNC pro grams. In the
event that a re vi sion may not be per ma nent (the de sign en gi neer may de lete the re vi sion), many com panies main tain a mas ter copy of each CNC pro gram for ev ery re vi sion, mean ing a given op er ation for one
workpiece may even tu ally have sev eral CNC pro grams. The setup per son and/or CNC op er a tor must be
very cau tious to con firm that the CNC pro gram they are about to run will ma chine the workpiece to its
most re cent re vi sion. Doc u menting and main tain ing the re vi sion in for ma tion at the be gin ning of ev ery
CNC pro gram makes this check ing easy.
Pro cess changes may also oc cur. Even if the workpiece re vi sion stays the same, the pro gram mer may
elect to incorporate new tooling, workholding devices, or machining order to improve qual ity or cy cle
time. The pro gram re vi sion should be doc u mented on the setup sheet and in the CNC pro gram so the
setup per son can con firm they are run ning the most re cent ver sion of the pro gram.
Also no tice the spec i fi ca tion of run time. Once the pro gram has run, it can be help ful to doc u ment its run
time right in the CNC pro gram (es pe cially for a re peat ing job). Any one look ing at the pro gram in the future, while the pro gram is not cur rently run ning, can eas ily de ter mine how long the pro gram takes to
run. Ad di tionally, there are things that oc cur in setup that may af fect the run time. If for ex am ple, tools
are loaded in a ma chin ing cen ter’s tool mag a zine in se quen tial or der, tool chang ing time will be min imized (even with ran dom ac cess tool chang ers if ma chin ing time is very short for a given tool). When the
job does run again, the setup per son can con firm that it is run ning as ef fi ciently as it has i n the past if the
run time is in cluded in the pro gram header.
3.1.2.2. Tool in for ma tion
A CNC pro gram, es pe cially a long one, can be quite dif fi cult to read, even for ex pe ri encedCNC setup people and op er a tors. Since the CNC op er a tor will be hav ing to re run tools of ten, the CNC pro gram mer can
make it much eas ier to find crit i cal re start po si tions in the pro gram by doc u ment ing the be gin ning of every tool. By hav ing this doc u men ta tion avail able in the pro gram, the CNC op er a tor can eas ily con firm
that they have found the cor rect po si tion within the CNC pro gram from which to start a given tool. Here
is an ex am ple turn ing cen ter pro gram which il lus trates this tech nique.
O0001
(*** PRO GRAM QUAL IFIED 2/12/99 ***)
(
MA CHINE: MORI SEIKE SL4)
( PART NUMBER: A-2355-2C)
Page 3-4
(
PART NAME: BEARING FLANGE)
(
RE VI SION: F)
(
CUS TOMER: ABC COM PANY)
CNC Concepts, Inc.
(
OP ER A TION: 20, MA CHINE BORED END OF PART)
( PRO GRAMMER: MLL)
(DATE FIRST RUN: 4/11/98)
(PRO GRAM RE VI SION: C)
( LAST PRO GRAM RE VI SION: 1/30/98 BY CRD)
(
RUN TIME: 00:05:25)
N005 T0101 M41 (ROUGH TURNING TOOL)
N010 G96 S400 M03
N015 G00 X3.040 Z0.1
N020 G01 Z-1.995 F0.017
N025 X3.25
N030 G00 X6.0 Z5.0
N035 M01
N040 T0303 M41 (2" DRILL)
N045 G97 S300 M03
N050 G00 X0 Z0.1
N055 G01 Z-2.6 F.009
N060 G00 Z0.1
N065 G00 X6.0 Z5.0
N070 M01
N075 T0404 M41 (1.5" ROUGH BORING BAR)
N080 G96 S400 M03
N085 G00 X2.085 Z0.1
N090 G01 Z-1.995 F0.010
N095 X2.0
N100 G00 Z0.1
N105 X6.0 Z5.0
N110 M01
N115 T0505 M42 (1.5" FIN ISH BORING BAR)
N120 G96 S600 M03
N125 G00 X1.125 Z0.1
N130 G01 Z-2.0 F0.006
N135 X2.0
N140 G00 Z0.1
N145 G00 X6.0 Z5.0
N150 T0202 M42 (FIN ISH TURNING TOOL)
N155 G96 S600 M03
N160 G00 X3. Z0.1
N165 G01 Z-2.0 F0.006
CNC Concepts, Inc.
Page 3-5
N170 X3.25
N175 G00 X6.0 Z5.0
N180 M01
N185 M30
No tice how in lines N005, N040, N075, N115, and N150, the mes sage makes it clear as to which tool is being used. An op er a tor wish ing to re run the fin ish bor ing bar, for ex am ple, could eas ily con firm that line
N115 is the cor rect block from which to start. Also note that the spaces in this pro gram fur ther sep a rate
tools. These spaces can be inluded by en ter ing an ex tra end-of-block character.
3.1.2.3. At ev ery pro gram stop
De pending upon the ma chin ing op er a tions be ing per formed, there may be times when the CNC operator
must per form a spe cial (man ual) task dur ing the CNC pro gram’s ex e cu tion at a pro gram stop, com monly
com manded by an M00. For ex am ple, a ver ti cal ma chin ing cen ter pro gram may be per form ing sev eral
tap ping op er a tions. Due to chips build ing up in side the holes, the CNC pro gram mer may in c lude a program stop just be fore the tap ping op er a tions. Dur ing this pro gram stop, the op er a tor isex pected to brush
away the chips and add tap ping com pound to the holes. In or der to con firm that the CNC op er a tor knows
what it is they are sup posed to do, the CNC pro gram mer should place a mes sage in the pro gram close to
the pro gram stop com mand.
.
.
N095 M00 (CLEAR CHIPS AND ADD TAPPING COM POUND)
.
.
Other in stances of when the CNC op er a tor may be ex pected to per form man ual op er a tions in this fash ion
that should be well doc u mented in clude break ing cer tain clamps loose on ma chin ing cen ters for fin ish ing
op er a tions, re duc ing chuck pres sure on turn ing cen ters for fin ish ing op er a tions, and turn ing a workpiece
around in the chuck of a turn ing cen ter to ma chine the op po site end of the workpiece. Truly, any time a
pro gram mer in cludes a pro gram stop in the pro gram, a mes sage should be in cluded close-by totell the oper a tor what it is they are sup posed to do.
Mes sages used for this pur pose as sume the op er a tor is mon i tor ing the pro gram page of the con trol’s display screen. In this case, when the ma chine stops due to the M00, the mes sage will be vis i ble. How ever, if
the op er a tor is mon i tor ing an other page of the dis play screen, say the po si tion page, the mes sage will not
be vis i ble. The op er a tor can, of course, sim ply ac ti vate the pro gram page to see the message. How ever,
this as sumes the op er a tor knows that the ma chine stopped due to an M00 (the ma chine is n’t hung up for
an un ex plained rea son).
Some con trols al low a more fail-safe method of dis play ing mes sages dur ing a pro gram stop. At the program stop, the dis play screen of the con trol will au to mat i cally switch to a spe cial mes sage page and display the mes sage, re gard less of what dis play screen page the op er a tor hap pens to be mon i tor ing. The
ex am ple com mand we show is given in the for mat used with the most pop u lar ver sion of para met ric program ming, cus tom macro B.
#3006 = 101 (TURN PART AROUND)
In cus tom macro B lan guage, #3006 is a stop-with-message sys tem vari able. When this com mand is ex ecuted, the dis play screen of the con trol will au to mat i cally switch to the mes sage page. Mes sage num ber
MC101 that states “TURN PART AROUND” will be shown. Af ter the part is turned around in the chuck
and the op er a tor re ac ti vates the cy cle, the mes sage will dis ap pear (though the dis play will still be showing the mes sage page).
3.1.2.4. Sim ple setup in struc tions
With sim ple set ups, some pro gram mers like to in clude mes sages at the very be gin ning of the pro gram to
tell the op er a tor how to setup the job. The pro gram mer can be as ver bally spe cific as nec e s sary, let ting
the op er a tor know ex actly what is ex pected in the setup. Note that most CNC con trols limit the num ber
of characters that can be in cluded per mes sage to about 80 char ac ters. Also, to keep a mes sage from
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CNC Concepts, Inc.
Ad vanced CNC Fea tures, Func tions, and Concepts
Mod ule four
4.1. Ad vanced CNC fea tures, func tions, and con cepts
In mod ule three, we dis cussed nu mer ous ad vanced ap pli ca tions for rel a tively ba sic fea tures - fea tures
that would nor mally be in tro duced in a ba sic CNC course. It’s likely that you have had at least some ex peri ence with many of the fea tures in tro duced in mod ule three.
Here we’re go ing to dis cuss many im por tant CNC fea tures that are sel dom, if ever, even men tioned in
most ba sic CNC courses. We must point out, how ever, that many of these fea tures have a nar row fo cus in
their ap pli ca tion. For any given CNC fea ture dis cussed in this mod ule, the com pa nies that need it will
prob a bly use it on a reg u lar ba sis. But the ma jor ity of com pa nies may never need the feature.
For this rea son, many of the fea tures dis cussed in this mod ule will not be of im me di ate need. You must, of
course, know that a fea ture is avail able (and how it’s used) be fore you can be gin to ap ply it. Think of this
mod ule as ex pos ing you to what is avail able. For some dis cus sions, we may sim ply ac quaint you with the
fea ture and tell you why it’s avail able. Some day, you may have use for it. And this text should make a
great way to re view the fea ture at the time when it is im por tant to you.
4.1.1. Spe cial in ter po la tion types
The vast ma jor ity of CNC pro grams re quire but three mo tion types: rapid, straight line, and cir cu lar inter po la tion. And these mo tion types are well dis cussed in ba sic courses. We add to their ap pli ca tions in
mod ule three. Here in mod ule four, we pres ent the more ob scure in ter po la tion types. In ev ery case, the
in ter po la tion type will have a very spe cific ap pli ca tion. If you don’t have the ap pli cation, you’ll never
need the re lated in ter po la tion type. In ad di tion, most con trol man u fac tur ers will not pro vide these in terpo la tion types as a stan dard fea tures. Un less the ma chine tool builder de ter mines that they are an in tegral part of their machine and makes them standard, you’ll have to pay extra to get them. In this
dis cus sion, our main ob jec tive is to let you know what each ex tended in ter po la tion type is and when you
will need it. For the more pop u lar ones, we’ll also give ex tended pre sen ta tions about how they’re used.
4.1.1.1. He li cal in ter po la tion
He li cal in ter po la tion causes three axes to move to gether. Two of the axes (usu ally X and Y) move in a circu lar fash ion, while the third axis (usu ally Z) moves in a lin ear fash ion. The re sult ing mo tion re sem bles a
cork screw, but the ra dius of the cork screw re mains con stant.
Note that, like cir cu lar mo tion, he li cal mo tion re quires a plane se lec tion (G17, G18, or G19). In al most all
ap pli ca tions, you’ll be mill ing in the XY plane, so G17 must be in ef fect. Note that if you use a right an gle
head and mill threads in the XZ or YZ plane, you must in voke the re lated plane se lec tion com mand (G18
for XZ or G19 for YZ).
For most con trols, he li cal in ter po la tion is com manded by G02 and G03 (the same G codes used for cir cu lar
mo tion. The X and Y co or di nates, as well as the arc cen ter spec i fi ca tion (with R or I, J, & K), are spec i fied
in ex actly the same man ner in a he li cal mo tion com mand as they are in a cir cu lar mo tion com mand. However, he li cal mo tion ad di tion ally re quires a Z spec i fi ca tion.
By far, the most pop u lar ap pli ca tion for he li cal in ter po la tion is thread mill ing on a ma chin ing cen ter and
the bulk of this pre sen ta tion ad dresses how you use he li cal in ter po la tion for thread mill ing. How ever,
there are CNC ma chin ing cen ter us ers that use he li cal mo tion when mill ing pock ets. They’ll use it to
ramp in to the pocket, min i miz ing stress on the mill ing cut ter (the mill ing cut ter must, of course, be of a
cen ter-cutting type).
If you don’t per form thread mill ing op er a tions, and if you don’t feel you need to ramp into pock ets, you
don’t need he li cal in ter po la tion. For this rea son, many ma chine tool build ers do not provide he li cal in terpo la tion as a stan dard fea ture. You may have to pay ex tra to get it (al most all ma chine tool build ers make
it a field-installable fea ture, mean ing you can add it at any time).
He li cal in ter po la tion for thread mill ing
Thread mill ing is be com ing quite com mon-place in com pa nies us ing CNC ma chin ing cen ters. Any hole
that is too large to tap or re quires a better fit than can be achieved by tap ping can be thread milled. And
CNC Concepts, Inc.
Page 4-1
Mod ule Num ber Four
out side di am e ters that re quire threads that would nor mally re quire some kind of thread die can be eas ily
milled. An other ad van tage of thread mill ing (over tap ping) is that the di am e ter of the thread mill ing oper a tion is ad just able with cut ter ra dius com pen sa tion. When you tap, you have no con trol of the fi nal hole
size.
While thread mill ing is be com ing quite pop u lar, there are still some con fu sion re gard ing how it’s done.
Here we in tend to ex plain thread mill ing in de tail. This should help any one who has never had to per form
a thread mill ing op er a tion un der stand what is in volved with thread mill ing (it may also clar ify a few
things for peo ple that have per formed thread mill ing op er a tions). We’ll dis cuss some ba sicter mi nol ogy,
show the re lated tool ing, ex plain the meth ods, and pres ent the pro gram ming tech niques used for thread
mill ing.
1.
Ba sic ter mi nol ogy
Thread des ig na tion - As you know, all threads have two ma jor des ig na tions. First is the thread’s di am eter. This designation is the thread’s major diameter. The second has to do with the thread’s pitch
(crest-to-crest distance). If the thread is specified in inch fashion, this designation will be in
threads-per-inch. The pitch will be equal to one di vided by the num ber of threads per inch. If machining
an in ter nal 2"-8 thread, the ma jor di am e ter is two inches and the pitch is 1/8 (0.125) inch.
If work ing with a met ric thread, the pitch will be spec i fied as part of the thread des ig na tion (an ex ter nal
50-1.5 met ric thread has a fifty mil li me ter ma jor di am e ter and a 1.5 mil li me ter pitch). While there are
other im por tant des ig na tions re lated to thread ing (pitch di am e ter, thread depth, in cluded an gle, etc.),
gen er ally speak ing, these are the two most im por tant des ig na tions for pro gram ming a thread mill ing operation.
Blind ver sus through holes - When ma chin ing threads in holes, if the hole does not pro trude all the way
through the workpieces, it is called a blind hole. If it does, it is called a through hole. The type of hole
(blind or through) will have im pli ca tions re lated to the thread mill ing di rec tion.
Climb ver sus con ven tional mill - Just like any other mill ing op er a tion, you’ll be able to choose which style
of mill ing you’d like. If your ma chine al lows it (has am ple ri gid ity), we rec om mend climb mill ing whenever pos si ble since it pro duces the better fin ish. Note that you can per form your de sired method of milling (climb or conventional) and still machine the appropriate hand of thread (right or left hand). If
ma chin ing with a right hand cut ter (spin dle run ning in the for ward M03 di rec tion), ma chining an in ternal thread in a con ven tional mill ing man ner re quires a down ward, clock wise mo tion. This will ren der a
right hand thread. If you wish to mill in a climb mill ing fash ion, you must thread in an up ward, coun terclock wise man ner. This will still ren der a right hand thread.
To ma chine a left hand thread, you will need a left hand thread mill ing cut ter (spin dle will be run ning
coun ter clock wise). Con ven tional mill ing will re quire a down ward, coun ter clock wise mo tion. Climb milling will re quire an up ward clock wise mo tion.
Cut ter ra dius com pen sa tion - For con tour mill ing op er a tions, this fea ture al lows you to pro gram the work
sur face (not the cut ter’s cen ter line path). The setup per son will spec ify the cut ter ra dius (or di am e ter) in
the tool’s cut ter ra dius com pen sa tion off set. Dur ing ma chin ing, the CNC con trol will keep the cut ter the
ap pro pri ate dis tance (the cut ter’s ra dius) away from the pro grammed sur faces. As with any other milling op er a tion us ing cut ter ra dius com pen sa tion, you’ll be al lowed to size the sur faces be ing milled (the
thread) by ad just ing the cut ter ra dius com pen sa tion off set.
He li cal in ter po la tion - This mo tion type is re quired for thread mill ing. It will cause the cut ter to move
along a cir cu lar path in two axes while mov ing in a straight path along the third axis. If ma c hin ing in the
XY plane (G17) as you al most al ways will, X and Y will be gen er at ing the cir cu lar mo tion path while Z
forms the straight path mo tion. He li cal in ter po la tion is con sid ered by Fanuc to be an option. While many
ma chin ing cen ter man u fac tur ers in clude in their stan dard pack age of Fanuc op tions, you must con firm
your ma chines have he li cal in ter po la tion be fore you can thread mill.
Here’s a quick test you can per form to see if your ma chin ing cen ter has he li cal in ter po lation: Manually
move the axes to the mid dle of their trav els (at least 3-4 inches from the zero re turn po si tion in each axis)
and give this com mand in man ual data in put (MDI) mode:
G17 G91 G02 I-1.0 Z-1.0 F30.0
Page 4-2
CNC Concepts, Inc.
This he li cal mo tion com mand tells the con trol to make a two-inch-diameter full cir cle clock w ise mo tion in
XY while mov ing down one inch in Z at thirty inches per min ute. If the ma chine ex e cutes this command,
it has he li cal in ter po la tion. But if it gen er ates an alarm (prob a bly hav ing to do with im proper plane se lection) it does not have he li cal in ter po la tion.
Fanuc and Fanuc-compatible con trols use G02 and G03 for thread mill ing. As with cir cu lar mo tion, G02
is clock wise mo tion and G03 is coun ter clock wise mo tion (in XY). The arc size can be spec i f ied with R or I
& J and all rules re lated to mak ing cir cu lar mo tions still ap ply. A Z de par ture is also spec i fied along with
the feedrate.
Arc-in ap proach and es cape - As when mill ing coun ter-bored holes (just XY cir cu lar move ment), it is impor tant to arc-in and arc-out to and from the thread be ing ma chined. If you don’t, a nasty witness mark
will be left at the end point of the ap proach or the be gin ning point of the es cape. While a small wit ness
mark may some times be ac cept able when mill ing a coun ter-bore, the wit ness mark left dur ing thread
mill ing (with out an arc-in ap proach) will be much worse - so much worse that the thread will prob a bly be
un ac cept able. As with the ma chin ing of the thread it self, the arc-in and arc-out ap proach m ust be in the
form of a he li cal mo tion.
2. Thread mill ing cut ters
While there will al ways be po ten tial in ter fer ence to deal with when ma chin ing in ter nal threads, any
style of thread mill ing cut ter can ma chine both in ter nal and ex ter nal (fe male and male) threads. The
next draw ing shows the three most com mon forms of thread mill ing cut ters. Each has its pros and cons
re lated to ef fi ciency and flex i bil ity.
Three styles of thread mill ing cut ters.
One (the one on the left) re sem bles a slot ting cut ter hav ing the thread form (60 de gree an gle) ma chined
into its out side di am e ter. A vari a tion of this style of cut ter is a bor ing bar fly-cutter with the thread form
ma chined into the tool’s in sert. This is the least ex pen sive style of thread mill ing cut ter, since it can be
made right in the com pany from ex ist ing tool ing by the peo ple who need it. The ma jor ad vantage of this
style of cut ter is that it can ma chine threads with any pitch. The ma jor dis ad van tage is that it will re quire sev eral cir cu lar passes to ma chine the thread to its spec i fied depth. For ex am ple, at least eight
passes will be required for a 2"-8 thread (having a 0.125 pitch) machined through a one inch thick
workpiece (one inch thick di vided by 0.125 pitch). This does not in clude the arc-in and out ap p roach and
es cape move ments.
The other two styles of thread mill ing cut ters are spe cif i cally made for thread mill ing. One (the one in the
mid dle) re sem bles a cross be tween a hog mill ing cut ter and a tap. Com monly made of high speed steel or
co balt (they are also avail able in car bide), this type of cut ter is more ex pen sive, but it can ma chine to a
depth of sev eral pitches in one pass around the thread. In many cases, the en tire thread can be machined
in one pass around (not in clud ing the ap proach and es cape). This, of course, dra mat i cally min i mizes cycle time as com pared to the pre vi ous style of thread mill ing cut ter (though no thread mill ingop er a tion
can beat the ef fi ciency of tap ping). One dis ad van tage (other than its higher price) is that this style of
thread mill ing cut ter can only ma chine one spe cific pitch. If made for a 0.125 inch pitch (eight threads per
inch), for ex am ple, the thread mill ing cut ter can not ma chine a 0.0625 pitch (six teen threads per inch).
One other lim i ta tion of this style of thread mill ing cut ter is that it is quite dif fi cult to sharpen. Many compa nies sim ply re place them when they’re dull.
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Page 4-3
The third style of thread mill ing cut ter (the one on the right) is be com ing the most pop u lar style since it
over comes most of the lim i ta tions of the two pre vi ous styles. Its cut ting edge is pro vided by a car bide (or
coated car bide) in sert. The de sired pitch is ma chined into the in sert it self. If you need to ma chine a
thread with a dif fer ent pitch, you sim ply use a dif fer ent in sert. Since each in sert has the form of sev eral
pitches, you can ma chine sev eral pitches in one pass around the thread. Again, you can usu ally machine
the en tire thread with one pass around (not in clud ing ap proach and es cape). This thread milling cut ter is
also rel a tively eco nom i cal, since only the in sert is re placed when it gets dull. Tool mainte nance (in sert replace ment) is also faster for the same rea son. Since the in sert is made of car bide (not hss), it’s also quite
ef fi cient, al low ing rather fast cut ting speeds.
Mul ti ple depths - If ei ther of the last two styles of thread mill ing cut ters can not ma chine a thread to its total depth in one pass, re mem ber that mul ti ple passes can be eas ily made. The trick to do ingso is sim ply to
make the sec ond (and suc ces sive) Z pass in even in cre ments of the thread’s pitch.
Right hand ver sus left hand threads - Only the first cut ting tool (the slot-milling cut ter style on the left)
can ma chine both left and right hand threads. The other two styles must be spe cially made in right- or
left-hand ver sions. A right hand cut ter ma chines only right hand threads. This cut ter will be ro tat ing in
the for ward di rec tion (M03) as threads are ma chined. A left hand cut ter (ro tat ing in the re verse di rection) will ma chine left hand threads.
A misconception about feeds and speeds - When it comes to cutting conditions, some people confuse
thread mill ing with tap ping. As you know, tap ping re quires per fect syn chro ni za tion be tween feed and
speed (feedrate must be set to rpm times thread pitch). If feed and speed are not syn chro nized, the tap
will break. This kind of syn chro ni za tion is not re quired for thread mill ing. While you must ma chine with
ap pro pri ate cut ting con di tions, the feedrate will have noth ing to do with the thread’s pitch. Sim ply cal culate speed and feed as you would for any mill ing cut ter (use the rec om men da tions sup plied by the thread
mill ing cut ter’s man u fac turer).
3.
Your ap proach to thread mill ing
The ba sic ma chin ing prac tice of thread mill ing is based upon sev eral fac tors. Here we of fer a few sug gestions.
Climb or con ven tional mill ing? - This is prob a bly the most im por tant ques tion re lated to how you mill
threads. While some light duty ma chines are in ca pa ble of climb mill ing (their way sys tems can not support it with out vi bra tion), most ma chin ing cen ter have am ple ri gid ity to al low climb mill ing. Since climb
mill ing pro vides better sur face fin ish, most pro gram mers use climb mill ing tech nique when e ver pos si ble.
For right hand in ter nal threads (spin dle run ning for ward - M03), this means ma chin ing the thread in a
coun ter clock wise (G03) di rec tion while com ing out of the hole (bot tom to top). For right hand ex ter nal
threads, this means ma chin ing the thread in a clock wise di rec tion (G02) while mov ing neg a tive in Z (top
to bot tom). Re verse the cir cu lar mo tion for left hand threads (con ven tional mill ing re quires a down ward
coun ter clock wise di rec tion with the spin dle run ning in re verse M04).
Am ple cool ant (or air blow) to re move chips - Chips ma chined at the be gin ning of the thread ing op er a tion
can not be al lowed to in ter fere with ma chin ing at the end of the thread. If chips are al lowed to ac cu mulate, it’s pos si ble that they will be re-machined sev eral times as the thread is ma chined. This can re sult in
poor sur face fin ish, or worse, vari a tions in thread size. This prob lem can be most trou ble some on hor i zontal ma chin ing cen ters, since chips do not freely fall from the ma chin ing op er a tion. This is an other rea son
to climb mill in holes, es pe cially on ver ti cal ma chin ing cen ters. The up ward mo tion of the thread mill ing
cut ter in Z will tend to make the cut ter avoid re-machining chips.
Blind or through hole? - This also has to do with chip re moval. Again, you must en sure that chips are
washed from the hole. This is eas i est to do with through holes, and es pe cially on ver ti cal ma chin ing centers (chips will sim ply fall through the hole). How ever, if ma chin ing blind holes, it can be very dif fi cult to
wash chips out of the hole, es pe cially on ver ti cal ma chin ing cen ters. This is an other reason to use climb
mill ing (bot tom to top) tech nique. As the thread is ma chined, the thread mill ing cut ter will be com ing out
of the hole. At the end of the thread mill ing op er a tion it will be one pitch higher than it was at the start.
This pro vides ad di tional clear ance for chips. As long as your ma chine has the ri gid ity to climb mill, use a
bot tom to top mo tion (coun ter clock wise mo tion - G03) when thread mill ing blind holes on verti cal machin ing cen ters.
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CNC Concepts, Inc.
Ap proach/es cape po si tion - This sug ges tion has to do with the po ten tial for chip in ter fer ence on hor i zontal ma chin ing cen ters (it is not a fac tor on ver ti cal ma chin ing cen ters). Since chip re m oval can be a problem, we rec om mend start ing the thread mill ing op er a tion at the X mi nus side of the hole (the nine o’clock
po si tion as viewed from the spin dle nose) if mill ing from the hole bot tom to its top. With this method, you
can min i mize the amount of chips that will be at the Y mi nus side of the hole (six o’clock po si tion) when
the thread mill ing cut ter passes by this po si tion. This can be es pe cially im por tant with blind holes when
chip re moval is most dif fi cult. A good cool ant sys tem, of course, will over come any prob lems re lated to
chip re moval.
4. Pro gramming con sid er ations
Some (but not many) con trols have a spe cial canned cy cle for thread mill ing. Ad di tionally, i f your con trol
has para met ric pro gram ming, you can de velop your own spe cial thread mill ing cy cle (we’ll pro vide an
thread mill ing ex am ple para met ric pro gram in a fu ture mod ule). If your con trol has para m et ric program ming, or if it has a spe cial cy cle for thread mill ing, by all means, study its use. These fea tures will
dra mat i cally sim plify the com mands re lated to thread mill ing. This pre sen ta tion will assume you do not
have ei ther fea ture.
As stated, Fanuc (and most con trol man u fac tur ers) use G02 and G03 for clock wise and coun ter clockwise
he li cal mo tion. And ev ery thing you know about pro gram ming cir cu lar mo tions still ap plies (end point is
spec i fied in X and Y, R can be used to spec ify ra dius for mo tions up to 180 de grees, I & J can be used to
spec ify full cir cle mo tion, etc.). But as we’ve also men tioned, a he li cal mo tion com mand ad di tion ally requires the spec i fi ca tion of a Z axis de par ture. This will cause the cut ter to move in a cir cu lar path in XY
and a lin ear path in Z. The re sult re sem bles a cork screw mo tion. But the ra dius of the cork screw will remain con stant (the ra dius changes in a true cork screw mo tion).
The trick to cor rectly pro gram ming thread mill ing op er a tions is match ing the Z axis de parture dis tance
in each he li cal mo tion com mand to the thread pitch. How much the thread mill ing cut ter must de part in
Z is re lated to the per cent age of a full cir cle that is be ing com manded in XY. If mak ing a full cir cle movement in XY, for ex am ple, the thread mill ing cut ter must de part by the pitch of the thread in Z . If mak ing a
half cir cle (180 de gree) move ment in XY, the thread mill ing cut ter must de part by one-half the pitch in Z.
If mak ing a one-quarter cir cle (as is com monly the case when mak ing arc-in and arc-out mo tions) movement in XY, the thread mill ing cut ter must de part by one-quarter of the pitch in Z.
Re mem ber that arc in and arc out ap proach and es cape move ments must also be pro grammed with a he lical mo tion. If you al ways make arc in and arc out ap proach and es cape mo tions with one-quarter cir cle
(90 degree) motions, the Z axis departures during approach and escape motions will always be
one-quarter of the pitch. But if you are try ing to min i mize cy cle time by keep ing the ap proach and es cape
po si tions closer to the sur face be ing thread milled, you must de ter mine the per cent age of a full cir cle being made dur ing the ap proach and es cape mo tions (in XY) in or der to cal cu late the ap pro pri ate Z de parture. The next draw ing stresses the point.
Arc-in mo tions. You must de ter mine the per cent age of a full cir cle in or der to de ter mine how much to make the
Z axis move dur ing the he li cal mo tion.
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Page 4-5
The pre vi ous il lus tra tion, the left draw ing shows the thread mill ing cut ter mak ing a one-quarter (90 degree) arc in ap proach. If this thread has twelve threads per inch, the pitch is 0.0833 inch. Dur ing this approach, since the mill ing cut ter is de part ing one-quarter of a full cir cle in XY, it must de p art one-quarter
of the pitch (0.0208 inch) in Z. But no tice that the mill ing cut ter will be “cut ting air” during much of this
ap proach mo tion. The draw ing on the right shows how to min i mize this air cut ting time, but requires
that you know the per cent age of a full cir cle be ing com manded in XY. Since we’re de part ingone-eighth of
a full cir cle (45 de grees), this ap proach would re quire a de par ture in Z of one-eighth the pitch (1/8 of
0.0833 is 0.0104 inch).
An ex am ple
The next il lus tra tion shows the draw ing to be used for the ex am ple pro gram.
Draw ing for thread mill ing ex am ple
We’ll be us ing a one inch di am e ter, right-hand thread mill ing cut ter that can ma chine the en tire thread
in one cir cu lar pass (not in clud ing ap proach and es cape). To get the best fin ish, we’ll use climb mill ing
tech niques (bot tom to top with coun ter clock wise - G03 - mo tion)
The thread mill ing cut ter will first be sent to the cen ter of the 0.75 inch ap proach ra dius (point 1) in X and
Y (X1.5, Y1.75) to be gin. Tool length com pen sa tion will then be in stated dur ing the cut ter’s Z axis approach to a po si tion just above the work sur face in Z (Z0.1). Prior to be gin ning the se ries of he li cal motions to ma chine the thread, we’ll po si tion the cut ter be low the bot tom of the workpiece in Z with enough
room to make a full cir cle com ing up (Z-0.7). Cut ter ra dius com pen sa tion will be in stated on the movement from point one to two.
It can be a lit tle cum ber some to spec ify Z axis de par tures in the ab so lute mode, but that’s what our ex ample will. If you feel more com fort able do ing so, re mem ber that you can po si tion the XY mo tions in ab so lute
mode while de part ing in Z in the in cre men tal mode. Con sider the fol low ing com mand.
N185 G90 G03 X1.5 Y2.5 R0.75 G91 Z-0.0312
No tice how it causes the ma chine to move in the ab so lute mode (G90) for the XY de par ture, but in in cremen tal for the Z de par ture. While not all con trols al low this tech nique, it can sim plify your thread milling com mands if your con trol/s al low it.
For the move ment from point two to point three (1/4 cir cle), the cut ter must de part in Z by one-quarter of
the pitch (0.0312 for this thread). Since the Z start ing po si tion for this mo tion is Z-0.7, the cor rect end
point in Z for this ap proach mo tion will be Z-0.6688. On the move ment from point three to point four (1/2
circle), it must depart one-half the pitch (0.0625 inch). The correct end point for point three will be
Z-0.6063. For the move ment from point four to point five (1/2 cir cle again), the tool must de part an other
one-half the pitch (end point: Z-0.5438). And fi nally, as the tool arcs off the thread to point s ix (1/4 cir cle),
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Para met ric Programming
Mod ule five
5.1. In tro duc tion to para met ric pro gram ming
Para met ric pro gram ming is the best kept se cret of CNC! There are few in this in dus try that even know
what para met ric pro gram ming is, and fewer still who know how to ap ply it. Though this is the case, almost all CNC us ers have ex cel lent ap pli ca tions for para met ric pro gram ming, and as a con se quence, under-utilize their CNC equipment. It is likely that your own CNC machine tool utilization can be
dra mat i cally im proved by in cor po rat ing para met ric pro gram ming tech niques in your CNC e nvironment.
5.1.1. What is para met ric pro gram ming?
Para met ric pro gram ming goes by many names. Fanuc (or any con trol man u fac turer that claims to be
100% Fanuc-compatible) calls it cus tom macro. Fadal calls it macro. Okuma calls it user task. Sodick
calls it Q rou tine. Kear ney & Trecker calls it ad vanced pro gram ming lan guage (APL) for their Gem ini
con trols. Sharnoa calls it arithmetics. Some con trol man u fac tur ers have para met ric pro gram ming ca pabil i ties but have not named it with any spe cial name. Bridgeports Boss Se ries con trols, for ex am ple, have
ex cel lent para met ric pro gram ming func tions yet these fea tures are sim ply in cluded with other G code
level pro gram ming func tions.
Even within a given con trol man u fac tur ers prod uct line there may be vari a tions in para metric pro gramming func tions. Fanuc, for ex am ple, has cus tom macro ver sion A and ver sion B, with ver sion B be ing
more pow er ful and eas ier to use. Which ver sion of cus tom macro you have is based on which control
model you pur chase within Fanucs prod uct line. In sim i lar fash ion, Okuma of fers user task 1 and user
task 2, with user task 2 be ing more pow er ful and eas ier to use.
While the vari a tions from one ver sion of para met ric pro gram ming to an other lead to dif ferences in specific us age tech niques, the broader ap pli ca tions and us age for para met ric pro gram ming remain re markably sim i lar. This is ev i denced by the fact that the ma jor ity of spe cific ap pli ca tions de scribed in this text
can be adapted to al most ev ery ver sion of para met ric pro gram ming just men tioned. Just as a given software ap pli ca tion can be han dled by a va ri ety of com puter pro gram ming lan guages (BA SIC, C Lan guage,
PASCAL, etc.), so can a given CNC ap pli ca tion be han dled with a va ri ety of para met ric pro gram ming versions.
5.1.1.1. Com par i son to subprogramming
The best way to get com fort able with any com plex sub ject mat ter is to com pare it to sim pler top ics with
which you may al ready be fa mil iar. Para met ric pro gram ming is no ex cep tion. If, for ex am ple, you have
worked with the subprogramming func tions of your con trol, you have scratched the sur face of what can
be done with para met ric pro gram ming.
All CNC con trols have subprogramming func tions to al low com mands within the CNC pro gram to be repeated. This min i mizes the num ber of com mands that must be given in the CNC pro gram. If, for instance, five iden ti cal pock ets must be milled in five workpieces on a ma chin ing cen ter dur ing the same
cut ting cy cle, it would be cum ber some to pro gram each pocket in de pend ently. In stead, the programming
com mands nec es sary to ma chine but one of the pock ets can be pro grammed. These re dun dant com mands
can be ex e cuted five times to ma chine the five pock ets, elim i nat ing many cum ber some, lengthy, and er ror
prone com mands.
While the spe cific com mands re lated to subprogramming vary from one con trol man u fac turer to an other,
one pop u lar con trol man u fac turer (Fanuc) uses an M98 to call a subprogram. A P word within the M98
specifies the subprogram num ber. An L word spec i fies the num ber of ex e cu tions of the subprogram.
With this con trol, the com mand
N050 M98 P1000 L5
tells this con trol to ex e cute subprogram O1000 five times. As long as pro gram O1000 con tains the commands needed to cor rectly ma chine one of the pock ets, the pro grams length can be short ened and the poten tial for mis takes is re duced.
Subprogramming tech niques are ob vi ously very help ful. How ever, if any thing changes from one pocket
to the next (width, height, depth, etc.), sim ple subprogramming tech niques can not be used. Without
para met ric pro gram ming, each pocket must be pro grammed in de pend ently. In ad di tion to giv ing the
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Page 5-1
Mod ule Five
programmer the abil ity to re peat re dun dant com mands, para met ric pro gram ming al lows anything to
change from one ex e cu tion of the para met ric pro gram to the next. In the pocket ex am ple, if any pocket attrib ute changes from one pocket to the next (width, height, depth, etc.) these vari a tions can be eas ily handled within the para met ric pro gram.
In this sense, para met ric pro gram ming gives the programmer the ability to write a general purpose
subprogram. If you have ever found yourself wishing you had the ability to write general purpose
subprograms, you have an ap pli ca tion for para met ric pro gram ming.
As you will see in the next chap ter, the things that change from one pocket to the next are called ar guments. Some ver sions of para met ric pro gram ming let you name the ar gu ments be ing passed to the paramet ric pro gram in a very log i cal man ner. Fanucs cus tom macro B, for ex am ple, uses a G65 com mand to
call the para met ric pro gram. Let ters of the al pha bet can be in cluded in this com mand to spec ify ar gument val ues. In the com mand
N050 G65 P1000 X2.0 Y1.5 W4.0 H2.0 D.25
G65 tells the con trol this is a cus tom macro call state ment. The P word still spec i fies the p ro gram num ber
of the para met ric pro gram that does the pocket mill ing. X and Y are be ing used to spec ify the lower left
hand cor ner po si tion of this pocket along the X any Y axis. W is be ing used to spec ify the pocket width, H
is spec i fy ing the height of the pocket, and D is spec i fy ing the pocket depth.
No tice how log i cal this ver sion of para met ric pro gram ming makes the en try of val ues that change from
one pocket to an other. Any one can eas ily rec og nize the mean ings of X, Y, W, H, and D. If an other pocket
of a dif fer ent size must be ma chined, an other G65 com mand can be eas ily spec i fied that contains dif ferent ar gu ment val ues.
5.1.1.2. Com par i son to canned cy cles
All CNC con trol man u fac tur ers do their best to cre ate a se ries of spe cial pro gram ming fea tures to min imize the work a pro gram mer must do. Al most all CNC ma chin ing cen ter con trols, for in stance, come
with a stan dard set of hole ma chin ing canned cy cles (typ i cally spec i fied by G81-G89). Some ma chin ing
cen ter con trols also have cer tain mill ing func tions like cir cle pocket mill ing, slot mill ing, thread mill ing,
and face mill ing. Turn ing cen ters com monly come with a set of canned cy cles for rough & fin ish turn ing
and bor ing, groov ing, hole ma chin ing, and thread ing.
Here are the com mands to drill a se ries of holes on one pop u lar ma chin ing cen ter con trol.
.
.
.
N065 G54 G90 S400 M03 (Se lect co or di nate sys tem, ab so lute mode, and start spin dle)
N075 G00 X1.0 Y2.0 (Rapid to first hole lo ca tion)
N080 G43 H01 Z0.1 (In state tool length com pen sa tion, move to Z ap proach po si tion)
N085 G81 R0.1 Z-0.75 F4.5 (Drill first hole)
N090 X3.0 (Drill sec ond hole)
N095 X5.0 (Drill third hole)
N100 X7.0 (Drill fourth hole)
N105 G80 (Can cel cy cle)
N110 G91 G28 Z0 M19 (Re turn to Z axis ref er ence po si tion)
.
.
.
In line N085, the first hole is com pletely ma chined based upon the con trols G81 func tion and the words
in cluded in the com mand (R, Z, F, etc.). The con trol will per form a se ries of strictly planned mo tions
based on the canned cy cles de sign. In the case of G81, the con trol will first rapid the tool to the XY po sition. Next it will rapid the tool to the R plane, plunge the tool to the hole bot tom, and re tract the tool from
the hole. With G81, four move ments are gen er ated with one com mand. With other canned cy cles (like
peck drill ing) many move ments can be caused by one com mand.
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No tice how sim i lar the G81 com mand for mat is to that of the pocket mill ing ex am ple call ing com mand
shown ear lier (for ver sion B cus tom macro). The R, Z, and F words in the G81 (or any canned cycle) are
like the ar gu ments be ing passed to the para met ric pro gram. You can think of all canned cy cles as be ing
like para met ric pro grams writ ten and main tained by the CNC con trol man u fac turer.
If your con trol does not have a needed canned cy cle, or if you do not agree with how a given canned cy cle
func tions, you can de velop a para met ric pro gram to han dle the ap pli ca tion. In es sence, you can cre ate
your own canned cy cles! If you have ever wanted the abil ity to cre ate your own canned cy cles,you have an
ap pli ca tion for para met ric pro gram ming.
5.1.1.3. Com par i son to com puter pro gram ming
If you have had ex pe ri ence with any com puter pro gram ming lan guage, you al ready know much of what is
avail able with para met ric pro gram ming. There are many com puter-related fea tures of para met ric program ming that closely re sem ble the com puter pro gram ming lan guage BA SIC (or just about any other
com puter pro gram ming lan guage). These fea tures in clude vari ables, arith me tic, logic, and loop ing and
are ex plained in de tail dur ing fu ture chap ters of part one. For now, suf fice it to say thatmost of what can
be done in BA SIC pro grams can be done within para met ric pro grams. By the way, if you have had no previ ous ex pe ri ence pro gram ming in BA SIC, we again rec om mend that you pick up a be gin ners book on BASIC. It will reinforce the presentations we make for computer-related features of paramet ric
pro gram ming. If you have ever found your self wish ing you could in clude com puter-programming-like
com mands in your CNC pro gram, you have an ap pli ca tion for para met ric pro gram ming.
5.1.2. Ap pli ca tion cat e go ries
As stated in the pref ace, there are count less ap pli ca tions for para met ric pro gram ming, andal most ev ery
CNC user has at least some good ap pli ca tions. In this dis cus sion, we or ga nize all ap pli ca tions for paramet ric pro gram ming into five ba sic cat e go ries.
Given the vast po ten tial ben e fits that can be at tained by uti liz ing para met ric pro gram ming, all CNC people should be able to rec og nize para met ric pro gram ming ap pli ca tions. In re al ity, this is far from true.
The vast ma jor ity of CNC peo ple have never even heard of para met ric pro gram ming. Of those t hat have,
few can rec og nize good ap pli ca tions (or have mis con cep tions of what re ally can be done). And fewer still
can ac tu ally de velop a para met ric pro gram once an ap pli ca tion is rec og nized.
The first step to doing any thing is know ing it is possi ble. Before you can uti lize the au to matic-frequency-searching-function of your ste reos FM tuner, you must first know it ex ists. In l ike manner, be fore you can solve any prob lem with para met ric pro gram ming tech niques, you must first know
which prob lems can be solved. In this dis cus sion, you will see many ap pli ca tions that can not be han dled
with nor mal G code level pro gram ming tech niques. In fact, many ap pli ca tions for para met ri c pro gramming are so re mark able that you may have trou ble be liev ing some of the claims we make. Whilewe do not
ac tu ally show how to han dle these ap pli ca tions in this in tro duc tory dis cus sion, rest assured each will be
well doc u mented in fu ture chap ters.
5.1.2.1. Families-of-parts
Many CNC us ers ma chine a se ries of very sim i lar workpieces. Groups of sim i lar workpieces are com monly called part fam i lies. Gen erally speak ing, all workpieces in a part fam ily closely re sem ble one another and re quire sim i lar (if not iden ti cal) ma chin ing op er a tions. In per fect part fami lies, only the size of
each workpiece changes.
Bolts, screws, nuts, wash ers, and pins, for ex am ple, are made in a va ri ety of sizes to suit the needs of indus try. The hex shaped sock ets a hand tool man u fac turer makes are made in var i ous sizes to accept
chang ing bolt and nut sizes. The rings a pis ton ring man u fac turer makes are made in var i ous sizes and
used with a va ri ety of pis ton sizes. The list of com mon part fam i lies is vir tu ally un limited.
The sim i lar ity among workpieces in a fam ily com monly cor re sponds to the sim i lar ity of the ma chin ing
pro cess used to ma chine each workpiece in the fam ily. For per fect part fam i lies, the same ma chin ing process and tool ing can be used to ma chine all workpieces in the fam ily. With con ven tional CNC pro gramming techniques, this results in a large number of very similar CNC programs. If you find yourself
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slightly mod i fy ing one CNC pro gram to cre ate an other, you have a fam ily-of-parts ap pli ca tion for paramet ric pro gram ming.
If you do any re peat busi ness, each hard and fixed CNC pro gram must be main tained. The larger the
num ber of workpieces in the fam ily, the more CNC pro grams are in volved. If an en gi neer ing change is
made to a part family containing thirty workpieces, thirty hard-and-fixed CNC programs must be
changed. Ad di tionally, the same ver i fi ca tion pro ce dures re quired for new CNC pro grams must be repeated thirty times as the mod i fied pro grams are run for the first time. Many CNC pro gram mers, setup
peo ple, and op er a tors dread en gi neer ing changes for these rea sons.
In sim i lar fash ion, if you wish to make a CNC pro gram change to im prove qual ity, in crease tool life, reduce ma chin ing time, or to achieve any im prove ment in the man u fac tur ing pro cess, the pro grams for all
workpieces in the part fam ily must be changed. This dra mat i cally lim its flex i bil ity and your abil ity to try
new things, since even mi nor im prove ments will in volve a great deal of work. All too of ten, pro cess improv ing changes are not in cor po rated due to the work in volved with mod i fy ing all of the pro grams involved.
With many fam ily-of-parts para met ric pro gram ming ap pli ca tions, only one base pro gram is re quired to
ma chine all workpieces in the en tire part fam ily. When ma chin ing a spe cific workpiece in the fam ily, argu ments (vari ables) will spec ify the value of each chang ing el e ment within the part fam ily. In es sence,
the para met ric pro gram within the CNC con trol is told which workpiece is cur rently be ing ma c hined.
How these chang ing ar gu ments are spec i fied var ies based on ap pli ca tion. In some com pa nies, the CNC
op er a tor or setup per son man u ally changes these ar gu ments dur ing setup. With Fadals macro lan guage,
it is even pos si ble to prompt for ar gu ments as the pro gram is ex e cuted. This func tion is programmed
much like the IN PUT state ment of BA SIC.
In other com pa nies, a CNC pro gram mer pro grams the changes. For per fect fam ily-of-parts ap p lications,
be lieve it or not, a CNC pro gram con tain ing the ar gu ments can even be au to mat i cally cre a ted by the produc tion con trol de part ment as a pro duc tion or der is is sued. More on how ar gu ments can be passed to the
para met ric pro gram in fu ture chap ters.
As you can imag ine, this dra mat i cally sim pli fies the long term pro gram ming of in di vid ual workpieces
(once the para met ric pro gram is de vel oped) and al lows for un lim ited mod i fi ca tions to be made right at
the CNC con trol, which dra mat i cally in creases flex i bil ity. In deed, go ing from one size workpiece to another is so sim ple that many com pa nies al low their CNC op er a tors to make the needed changes. Ad ditionally, mod i fi ca tions that af fect the en tire part fam ily (en gi neer ing and op ti miz ing changes) are much
eas ier to make. Only one pro gram need be changed!
1.
How are your prints dimensioned?
Some com pa nies uti lize vari able dimensioning tech niques for dimensioning a fam ily-of-parts. The design en gi neer will di men sion will di men sion val ues that change with a let ter of the al phabet. Any per son
view ing the draw ing will de ter mine the value of a given di men sion by ref er enc ing a chart in cluded on the
draw ing. Based upon know ing the workpieces part num ber, any one can find the val ues of each variable
di men sion. Fig ure 1.1 shows an ex am ple of this kind of fam ily-of-parts dimensioning. If your com pany
uses vari able dimensioning tech niques, you have a fam ily-of-parts ap pli ca tion for para met ric pro gramming.
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Fig ure 1.1
No tice in fig ure 1.1 that di men sions are spec i fied with let ters (A, B, C, etc.). Some ver sions of para met ric
pro gram ming even al low you to des ig nate the value of each ar gu ment to be passed to the paramet ric program with the same let ters as are used on the print. To spec ify that part num ber SC-0875 in fig ure 1.1 is
be ing made, for ex am ple, here is one way to do so by us ing Fanucs cus tom macro B.
N060 G65 P1000 A1.375 B0.875 C0.437 D0.1875
In this ex am ple, no tice how ar gu ments A, B, C, and D di rectly cor re spond to print di men sions (D spec i fies
the top hole di am e ter, which in turn, de ter mines how the rest of the hole must be ma chined). Though
there may be other chang ing at trib utes to be han dled by the para met ric pro gram mer for this application
(speed & speed vari a tions, tool sta tion num bers, etc.), this ex am ple com mand should nicely stress how
easy it is to spec ify which workpiece is to be ma chined.
The more workpieces in a part family, the easier it is to jus tify para met ric pro gram ming techniques.
Keep in mind, how ever, para met ric pro grams do take lon ger to write than con ven tional CNC programs.
From a strictly programming-time-based justification standpoint, it may be hard to jus tify writ ing a
para met ric pro gram for part fam i lies hav ing but a few workpieces. Even for sim ple workpieces, it will
take from 3-5 times as long to write the para met ric pro gram as it will to write a hard and fixed CNC program for one workpiece in the part fam ily.
Fam ily-of-parts pro gram struc ture
Though we may be get ting a lit tle deeper into spe cific is sues than we should dur ing this in tro duc tion of
ap pli ca tion cat e go ries, we wish to in tro duce an im por tant point rel a tive to fam ily-of-parts ap pli ca tions.
Most family-of-parts applications for parametric programming require but one program, commonly
called the main pro gram. While other pro grams could be in volved, the main pro gram is the parametric
pro gram for part fam ily ap pli ca tions. The ar gu ments that spec ify the val ues of each chang ing el e ment of
the part fam ily are com monly listed at the very be gin ning of this pro gram. These val ues will be ref erenced later in the pro gram, when ever they are needed. More on the dif fer ent meth ods of ar gument assign ment in fu ture chap ters.
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5.1.2.2. User cre ated canned cy cles
Even if your companys prod ucts con tain no part fam i lies, it is quite likely that you have at least some simi lar ma chin ing op er a tions that oc cur on sev eral workpieces. Para met ric pro gram ming can dra mat i cally
stream line the pro gram ming of re peated ma chin ing op er a tions. Many ma chin ing op er a tions are sim i lar
in na ture and eas ily han dled with para met ric pro gram ming tech niques. Here are some ex am p les you
should eas ily rec og nize.
Ma chining cen ters:
Thread mill ing
Round pocket mill ing
Rect an gu lar pocket mill ing
Cir cle mill ing
Face mill ing
Keyway mill ing
Slot mill ing
Hole ma chin ing (drill ing, tap ping, ream ing, bor ing, etc.)
Hole pat terns (bolt hole cir cle, grid pat tern, win dow pat tern, etc.)
Turn ing cen ters:
Groove neck ing
Tapping (many turn ing cen ters do not have this cy cle)
Deep hole peck drill ing (many turn ing cen ters do not have this cy cle)
Knurling
These ma chin ing op er a tions are quite com mon and many con trol man u fac tur ers have de vel o ped canned
cy cles to han dle at least some of them. While con trol-manufacturer-created canned cy cles are extremely
help ful, you know that they are fixed in their func tion. If you do not like the way they work, t here is lit tle
you can do about it. For ex am ple, the ma chin ing cen ter G83 deep hole drill ing cy cle is quite lim ited on
most con trols. Most con trols do not al low you to change the depth of each suc ces sive peck as the hole gets
deeper. Most do not al low you to com bine the chip break ing cy cle (G73 on many con trols) with the deep
hole drill ing cy cle. And the method by which the num ber of passes and the depth of each pass are cal culated may not be to your lik ing.
If you have ever found your self wish ing that your con trols canned cy cles worked dif fer ently,you have an
user-created canned cy cle ap pli ca tion for para met ric pro gram ming. Be lieve it or not, para met ric program ming ac tu ally gives you a way to im prove upon the canned cy cles that come with your ma chine tool.
In ad di tion to mod i fy ing the method by which your cur rent canned cy cles work, you have the additional
abil ity to cre ate your own canned cy cles with para met ric pro gram ming. Most ma chin ing cen ter con trols,
for ex am ple, do not have a canned cy cle for thread mill ing. If you per form thread mill ing on a reg u lar basis and if your con trol does not have a thread mill ing cy cle, you are likely writ ing many te dious, re dundant, and error prone commands. With parametric pro gramming, you can create your own thread
mill ing canned cy cle!
In sim i lar fash ion, most turn ing cen ter con trols do not in clude an ad e quate canned cy cle to machine
grooves. If you must neck grooves in many workpieces and if your con trol does not have a canned cy cle for
groov ing, again, you must write many te dious, re dun dant, and er ror prone com mands. With parametric
pro gram ming, you can cre ate your own groov ing cy cle!
Many com pa nies per form rather un usual op er a tions that are spe cific only to their own prod ucts and
man u fac tur ing pro cesses, and no con trol man u fac turer will con sider cre at ing canned cy c les for ma chining op er a tions that are not help ful to the ma jor ity of their us ers. Rel a tively few ma chin ing cen ter us ers,
for ex am ple, ma chine dove tails. This ma chin ing op er a tion nor mally re quires a num ber of successive
mill ing passes with a dove tail cut ter. As when chas ing a thread on a turn ing cen ter, the num ber of passes
and the depth per pass changes based on dove tail size, cut ter ma te rial and ri gid ity, and workpiece ma terial. If you ma chine dove tails, you have likely found there is no stan dard canned cy cle to help with these
te dious and er ror prone com mands. Wouldnt it be nice if you could com mand this op er a tion to be completed with one sim ple com mand? With para met ric pro gram ming, you can cre ate your own dove tail milling canned cy cle!
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Setup Time Reduction
6.1. Setup time re duc tion prin ci ples
Making a setup is a nec es sary sup port task. It does noth ing to add value to your prod uct. While all CNC
peo ple will agree that any thing that can be done to re duce setup time should be done, com pa nies vary dramat i cally with re gard to the lengths they will go to re duce setup time. Prod uct pro duc ing manufacturing
com pa nies tend to heavily staff their CNC en vi ron ments. Their goal is to keep the CNC ma chine tools
run ning for as high a per cent age of time as hu manly pos si ble. Any un nec es sary down time is seen as a
waste of time and they tend to do what ever it takes to elim i nate as much down time as pos si ble. On the
other hand, con tract shops tend to min i mize the num ber of peo ple in their CNC en vi ron ments. A con tract
shop tends to com pro mise wasted ma chine time dur ing setup for the abil ity to han dle all CNC related
tasks with as few peo ple as pos si ble.
Re gard less of the com pany type, setup time is com monly viewed as lost pro duc tion time, and all com panies should be highly in ter ested in min i miz ing this lost time. In this chap ter, we in tro duce the ba sic princi ples of setup time re duc tion. These prin ci ples can be ap plied to any form of man u fac tur ing equip ment,
in clud ing CNC ma chine tools. In the next chap ter, we will of fer many spe cific tech niques that can be applied to re duc ing setup time on your CNC ma chin ing cen ters and turn ing cen ters. Some of these prin ciples will even be help ful dur ing our dis cus sion of cy cle time re duc tion in chap ter nine.
6.1.1. The im por tance of re duc ing setup time
The num ber of workpieces you make per pro duc tion run (quan tity) is the pri mary fac tor that dic tates how
im por tant it is that you re duce setup time. The higher your pro duc tion quan ti ties, the greater the percent age of time that the ma chine will be in pro duc tion and the fewer the num ber of needed setups. With
very high pro duc tion quan ti ties, it may be pos si ble that as lit tle as five per cent (or less) of the ma chines
over all pro duc tion will be spent in setup. There are CNC ma chines, in fact, that are ded i cated to run ning
only one workpiece. Once the jobs setup has been made once, the ma chine will never be in setup again.
For com pa nies that spend less than about ten per cent of a given CNC ma chines time in setup, any re duction in setup time will have but a small im pact on the ma chines over all uti li za tion. While setup time reduc tion may still be con sid ered some what im por tant, we would rec om mend con cen trat ing on reducing
cy cle time (the sub ject of chap ter nine) as a way of im prov ing the CNC ma chines uti li za tion.
By far, the vast ma jor ity of CNC us ers run rel a tively low pro duc tion quan ti ties rang ing from one to five
hun dred workpieces. In deed, one of the pri mary rea sons for us ing CNC ma chine tools in the first place is
their abil ity to ef fi ciently run small lot sizes. In fact, many com pa nies (es pe cially in toolroom and pro totype en vi ron ments) run only one workpiece per pro duc tion run. Fig ure 1.1 de picts the two ex tremes related to per cent age of time spent in setup ver sus per cent age of time run ning pro duc tion.
Production Run
95.0%
Time In Setup
5.0%
Large
Quantities
Time In Setup
95.0%
Production Run
5.0%
Small
Quantities
Fig ure 1.1
It is likely that your com pany cur rently spends much more than five per cent of a given ma chines pro duction time in setup. The greater the per cent age of time spent in setup, the more im por tant it will be that
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you stream line your companys setup pro ce dures to re duce setup time, and the more your com panyshould
be will ing to in vest to achieve this goal. Achieving this goal will re sult in in creas ing the ma chines over all
per cent age of time spent ma chin ing workpieces, the value added time.
Keep in mind that the ex tremes in workpiece quan ti ties pres ent spe cial prob lems for in cor po rat ing setup
time re duc tion tech niques. For ul tra-high pro duc tion quan ti ties, we al ready men tioned that so lit tle of
the ma chines pro duc tion time will be in setup that it would be wiser to con cen trate on re ducing cy cle time
or workpiece load ing time. How ever, very low pro duc tion quan ti ties also pres ent spe cial prob lems for
setup time re duc tion. Many of the setup time re duc tion tech niques we show de pend on hav ing people
per form cer tain setup re lated tasks dur ing the pro duc tion run. If run ning only one or two workpieces
with a short cy cle time, it is likely that noth ing can be done dur ing the pro duc tion run to get ready for the
next setup.
Aside from pro duc tion quan ti ties, a sec ond fac tor that con trib utes to just how im por tant it will be to reduce setup time is the through-put of workpieces in your com pany. If your com pany in cor po rates just in
time (JIT) tech niques, it will be very im por tant to en sure that workpieces ar rive at each point along the
man u fac tur ing pro cess when planned. Any en hance ments that al low setup time re duc tion will help to
en sure the flow of workpieces.
Re gard less of how im por tant it is that you re duce setup time, do ing so can be quite chal leng ing. Given the
wide va ri ety of man u fac tur ing meth ods used to day, each com pany will have its own spe cial ob sta cles to
over come. Cer tain ma chine tools, for ex am ple, lend them selves to quick set ups better than oth ers. Bar
feed turn ing cen ters are gen er ally quicker and eas ier to setup than hor i zon tal ma chin ing cen ters. Di versity of work also pres ents spe cial setup re lated prob lems. Com panies that pro duce fam i lies of parts will
gen er ally find it eas ier to min i mize setup time than those who pro duce a wide va ri ety of very dif fer ent
workpieces. Avail able per son nel is yet an other vari able in the setup time equa tion. The more peo ple you
have avail able in your CNC en vi ron ment, the eas ier it will be to in cor po rate setup time reduc tion techniques. Even some thing as ba sic as the age of your ma chine tools can af fect how dif fi cult it will be to reduce setup time. The state-of-the-art in CNC tech nol ogy is con stantly chang ing. Newer ma chines have
func tions de signed to help min i mize setup time.
6.1.2. Jus ti fi ca tion for setup time re duc tion
Any setup time re duc tion pro gram will cost some thing. Even if you or your peo ple are sim ply ap ply ing a
tech nique that does not re quire a pur chase of some new de vice, the time it takes to in cor po r ate and test
the tech nique must be con sid ered. De pending on how your com pany op er ates, you may have to provide
jus ti fi ca tion for the time, per son nel, and money your com pany must in vest in the setup time re duc tion
pro gram. Doing so re quires an un der stand ing of ba sic jus ti fi ca tion prin ci ples.
Given the high cost of CNC ma chine uti li za tion, it should be rel a tively easy to jus tify most setup time reduc tion tech niques, es pe cially those that re quire an in vest ment in only time and ef fort. Since we are
talk ing about jus ti fy ing setup time re duc tion, your jus ti fi ca tion must be time based, mean ing you must
know the shop rate of the ma chine tool/s in volved.
When you have a setup time re duc tion tech nique that re quires jus ti fi ca tion, first cal cu late how much
your setup/s cur rently cost. Based on the ma chines shop rate and know ing how long it takes to make a
given setup, you can eas ily cal cu late this cost. Based on know ing how many times the setup is made per
week, month, year, etc., you can de ter mine how much your com pany spends on a given setup. If the improve ment you in tend to make will be ap plied to sev eral set ups, be sure to re peat this pro cess for each.
Sec ond, ap prox i mate the sav ings in time your im prove ment will pro vide per setup. You should be able to
eas ily cal cu late an ex pected sav ings based on the time saved, the ma chines shop rate, and the to tal number of set ups in volved. Com pare the po ten tial sav ings to the cost for im ple men ta tion in or der to de termine if your setup time re duc tion tech nique is jus ti fi able.
Re mem ber that a sav ings in setup time pro vides an equiv a lent in crease in pro duc tion time,mean ing reduc ing setup time pro vides a dou ble ben e fit. Not only are you sav ing ma chine time, you are increasing
the ma chines pro duc tive time. Re mem ber to fac tor this added sav ings into your setup time justification
equation.
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We can not stress enough the im por tance of know ing your cur rent costs re lated to mak ing set ups as you
be gin any setup time re duc tion pro gram. Only by know ing your cur rent costs can you jus tifyany in vestment in per son nel, time, ef fort, or equip ment needed to re duce it.
6.1.3. The re la tion ship be tween pro duc tion quan ti ties, pro cess, and setup time
As stated, the num ber of workpieces to be pro duced per pro duc tion run has the great est im pact on how
im por tant it is that you re duce setup time. In deed, pro duc tion quan ti ties dra mat i cally im pact all im portant de ci sions made for ma chin ing of a given workpiece, in clud ing the pro cess by which the workpiece is
produced.
Pro duc tion quan ti ties, pro cess, and setup de sign are very closely re lated. The num ber of workpieces to be
pro duced is the larg est sin gle fac tor that de ter mines how the pro cess should be en gi neered. Gen erally
speak ing, the more workpieces to be ma chined, the more im por tant it is that workpieces be ma chined effi ciently, re sult ing in a more elab o rate pro cess.
If, for ex am ple, only twenty-five workpieces are to be ma chined, the only real pri or ity may be ma chin ing
ac cept able workpieces. The pro cess en gi neer will use stan dard cut ting tools, and un less unavoidable,
noth ing spe cial will be pur chased for such a low pro duc tion quan tity. On the other hand, if one thou sand
workpieces are to be ma chined in one pro duc tion run, the pro cess en gi neer will likely de sign a com pletely
different process. Instead of sim ply hav ing to pro duce ac cept able workpieces, ac cept able workpieces
must be pro duced ef fi ciently. The higher the pro duc tion quan ti ties, the higher the em pha sis on ef ficiency. Much more en gi neer ing will go into the pro cess to min i mize ma chin ing time. The pu r chase of
spe cial com po nents re lated to the setup in clud ing spe cial cut ting tools, fix tures, and pos si bly even machin ery can be jus ti fied if pro duc tion quan ti ties are high enough.
Just as pro duc tion quan ti ties de ter mine how elab o rate the pro cess must be, so does the pro cess de termine how elab o rate the setup must be. Be cause quan ti ties are very high for a given job, for ex am ple, the
pro cess may call for mul ti ple workpieces to be ma chined in one ma chine cy cle. This, of course, re quires
the workholding setup to be ca pa ble of hold ing mul ti ple workpieces.
In sim i lar fash ion, just as the qual ity of the pro cess dic tates the re sult ing cy cle time, so is setup time a
slave to the pro cess. Gen erally speak ing, the over all qual ity and so phis ti ca tion of the setup will be a simple re flec tion of the pro cess, which is in turn a re sult of the num ber of workpieces to be machined.
As a simple anal ogy, we com pare the re la tion ship of pro duc tion quan ti ties, pro cess en gineering, and
setup de sign to match ing tires to your au to mo bile. Your tires should be cho sen to match the kind of car
you drive. If you drive a sports car, the qual ity of your tires must re flect the high per for mance ca pa bil i ties
of your car. If you buy tires that were de signed for a fam ily car, the tires will be the weak link in your
sports cars per for mance. If, on the other hand, you drive a fam ily car, pur chas ing high per f or mance tires
would be over-kill. The fam ily car now be comes the weak link. Just as tires must be cor rectly matched to
an au to mo bile to en sure that there are no weak links in the cars per for mance, so must pro duc tion quan tities, pro cess, and setup be matched to en sure that there are no weak links in the man u fac tur ing pro cess.
The en gi neer ing ef fort that goes into the de sign of the setup plays the big gest role in de ter min ing how
quickie the setup can be made. Just as ev ery pro cess could be en gi neered to al low the ab so lute min i mum
cy cle time, so can ev ery setup be en gi neered to al low the ab so lute min i mum setup time. How ever, fea sibil ity, based on pro duc tion quan ti ties, lim its how much en gi neer ing goes into the pro cess. In simi lar
fash ion, fea si bil ity, based on the pro cess, lim its the en gi neer ing that goes into the de sign of the setup.
Though the de sign of the setup plays a ma jor role in de ter min ing setup time, cut ting tool and fix ture design is be yond the scope of this text. While we freely ac knowl edge its im por tance in re duc ing setup time,
we limit our scope to of fer ing spe cific CNC tech niques to re duce setup time.
6.1.4. Setup time de fined
Our broad def i ni tion of setup time goes like this: Setup time it the time it takes to go from mak ing the last
workpiece in the pre vi ous setup to ef fi ciently mak ing the first good workpiece in the next setup. Since the
ma chine tool is down (not run ning pro duc tion), any thing that hap pens be tween pro duc tion runs must be
con sid ered as setup time.
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Here are some tasks com monly as so ci ated with set ting up CNC ma chine tools.
Tear-down of old setup
Making of workholding setup
Tool as sem bly
Tool mea sure ment (if re quired)
Tool load ing
Pro gram zero mea sure ment
Off set en try for tool ing in for ma tion
Off set en try for pro gram zero in for ma tion
Pro gram load ing
Pro gram ver i fi ca tion
First workpiece in spec tion
Mod i fi ca tions based on first piece in spec tion
Op ti mizing pro gram (for higher pro duc tion quan ti ties)
By our def i ni tion, sev eral tasks af fect setup time that you may not feel are truly part of a CNC ma chine
setup. Pro gram ver i fi ca tion, for ex am ple, though it is not ac tu ally part of the workholding or cut ting tool
setup, keeps pro duc tion from run ning and must be con sid ered as setup time. First workpiece inspection,
as well as the time it takes to make ad just ments to the CNC pro gram in or der to get a workpiece to pass
in spec tion, holds up pro duc tion and must be con sid ered as setup time. Pro gram op ti miz ing time, though
it may dra mat i cally im prove cy cle time, also holds up pro duc tion and must be con sid ered as part of the
setup. Time spent searching for tools, in serts, gauges, fix tures, and any thing else needed dur ing the
setup, must be con sid ered as setup time. Even lunch, breaks, and all forms of per sonal time, if taken
while a ma chine is down in setup, must be con sid ered as setup time - and com pa nies pay an ex tra pen alty
for per sonal time taken dur ing the setup of CNC ma chines that can run un at tended, like bar-feeding
turn ing cen ters. These ma chines can nor mally be run ning pro duc tion even dur ing breaks, lunch and
other per sonal time.
Though some of these func tions have noth ing to do with set ting up a CNC ma chine tool, most are necessary sup port tasks that hold up pro duc tion - and any thing that can be done to min i mize these tasks will
ef fec tively re duce setup time.
6.1.5. Find ing a place to start
As you con sider setup time re duc tion for any kind of ma chine tool, you should be gin by an a lyz ing your
cur rent setup pro ce dures. This will pro vide a point of ref er ence for any changes you make and, if done
cor rectly, it will usu ally help you to set pri or i ties with re gard to what changes will have the big gest impact on setup time.
We rec om mend in volv ing ev ery one in volved with de sign ing and mak ing set ups in your anal y sis. The
more ex perts you in volve, the more po ten tial you have for find ing the best, most fea si ble sug ges tions and
so lu tions. To pro vide you with some thing to an a lyze, we rec om mend video-taping the cur rent setup/s in
ques tion. Again, be sure to in vite ev ery one to an a lyze and cri tique the video/s.
You will find that some setup tasks dur ing setup take lon ger to per form than oth ers. The first step will be
to iso late each task in the setup pro cess to de ter mine what per cent age of the over all setup each task
takes. When fin ished, you can eas ily il lus trate the tasks re lated to the setup by mak ing a g raph sim i lar to
the one shown in Fig ure 1.2. This makes it very clear to ev ery one in volved in your anal y sis just how much
time each task takes and makes an ex cel lent start ing point for your setup time re duc tion ef fort. Those
tasks that take the most time gen er ally of fer the most po ten tial for im prove ment.
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CNC Concepts, Inc.
Fig ure 1.2
Since it takes time to video-tape the setup and or ga nize the re sults, you may be tempted to by p ass these
steps and pro ceed di rectly to in cor po rat ing the setup time re duc tion tech nique we show in the next chapter. Or you may be tempted to by pass these steps be cause you think you know what your setup people are
cur rently do ing. We urge you to avoid this temp ta tion for three rea sons. First of all, with no point of refer ence, you will have no way of gaug ing the im pact of the setup time re duc tion ef fort. Sec o nd, with out
this anal y sis, it is likely that you will not come up with the best so lu tions to your par tic u lar setup problems. Third, and most im por tantly, an a lyz ing ac tual set ups is the only way of truly see ing ex actly how
long setup re lated tasks truly take. If you have never in cor po rated setup time re duc tion tech niques, you
will prob a bly be very (un pleas antly) sur prised at just how much wasted time there is in your setups.
6.1.6. The two types of setup tasks
There are only two types of tasks re lated to mak ing set ups - those that are per formed while the ma chine
is down be tween pro duc tion runs and those that are per formed up-front, prior to the ma chin ing of the last
workpiece in the cur rent pro duc tion run. Tasks that are done while the CNC ma chine is down are called
on-line tasks (also called in ter nal tasks). Tasks that are done in prep a ra tion for the next setup are called
off-line tasks (also called ex ter nal tasks).
Some tasks that are com monly per formed as on-line tasks in clude tear ing down the old work hold ing
setup, mak ing the new work hold ing setup, load ing cut ting tools, mea sur ing cut ting tool lengths, measur ing pro gram zero, en ter ing off set val ues for cut ting tools and pro gram zero as sign ment, load ing the
CNC pro gram, ver i fy ing the CNC pro gram, and in spect ing the first workpiece. Some tasks that are commonly thought of as off-line tasks in clude pro gram ming, cut ting tool as sem bly, and lo cat ing fix tures,
gauges, and other tools needed for the next setup.
Com panies vary dra mat i cally with re gard to which tasks they per form on- or off-line. In deed, the size of
the com pany, the num ber of peo ple in the CNC en vi ron ment, and the en gi neer ing that goes into the design of the setup are but a few of the fac tors that con trib ute to which tasks should be on-line and which
should be off-line. Though this is the case, you must un der stand that the ac tual time your CNC equipment is down be tween pro duc tion runs (setup time) is the sum-total of the on-line tasks. Your CNC machine must be down (not pro duc tive) dur ing on-line tasks. It can be run ning pro duc tion dur ing off-line
tasks.
6.1.7. The three ways to re duce setup time
There are only three gen eral ways to re duce the time it takes to go from one pro duc tion run to the next,
mean ing ev ery setup time re duc tion tech nique we show will fit into one of these three cat e gories:
1) Elim i nate on-line tasks
2) Move on-line tasks off-line
3) Fa cil i tate on-line tasks
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Mod ule Six
Since setup time is the sum-total of on-line tasks, whenever you elim i nate an on-line task or move it
off-line, you ef fec tively re duce setup time by the length of time it was tak ing to per form the tasks on-line.
For this rea son, min i miz ing the num ber of on-line tasks that must be per formed dur ing setup should be
the high est pri or ity of any setup time re duc tion pro gram. By fa cil i tat ing the on-line tasks, we mean that
you must make it as easy (and ef fi cient) as pos si ble for the setup per son to per form on-line tasks. In this
chap ter, re mem ber that we are sim ply in tro duc ing setup time re duc tion e con cepts. In chap ter eight, we
will dis cuss in much greater de tail how they ap ply to CNC equip ment.
6.1.7.1. Elim i nating on-line tasks
By elim i nat ing on-line tasks, we mean find ing ways to make a setup with out need ing to per form cer tain
on-line tasks. Though your solution/s that eliminate on-line tasks can sometimes involve spending
money, it usu ally takes lit tle more than in ge nu ity and the de ter mi na tion not to give up un til an an swer is
found.
The evo lu tion of CNC tech nol ogy in re cent years has a lot to do your abil ity to elim i nate tasks that have
been tra di tion ally done on-line. Newer CNC con trols of fer fea tures that elim i nate the need to per form
cer tain tasks. One ex am ple of elim i nat ing an on-line task is re lated to the mea sur ing pro gram zero po sitions for ma chin ing cen ter pro grams (this is shown in much greater de tail in chap ter eight). Many compa nies re quire their setup per son to mea sure the pro gram zero po si tions for each setup they make. This
on-line task in volves tak ing three mea sure ments (one for X, one for Y, and one for Z) for each program
zero po si tion used within the pro gram. For hor i zon tal ma chin ing cen ter ap pli ca tions when ma chin ing on
sev eral sur faces, this can re quire sev eral mea sure ments - re sult ing in a great deal of wasted setup time.
By in cor po rat ing cur rent fix ture off set tech niques al lowed by todays CNC con trols, it is likely that these
re dun dant mea sure ments taken dur ing setup can be elim i nated. If some crit i cal ma chine mea sure ments
are taken once, early on in the ma chines use, the re sults of these mea sure ments can be used for ev ery
setup made. For ex am ple, the lo ca tion of the ma chine ta bles keyslots and crit i cal lo ca tion sur faces can be
mea sured one time. If your work hold ing tool ing is keyed to the ta ble us ing these keyslots, the pro grammer will be able to eas ily cal cu late the lo ca tion of each pro gram zero po si tion, elim i nat ing the on-line task
of mea sur ing pro gram zero for ev ery setup made. The pro gram mer can even in clude fix ture off set set ting
com mands in the pro gram, keep ing the setup per son from hav ing to en ter fix ture off set val ues man u ally,
elim i nat ing an other on-line task. Pro gramming fix ture off set val ues in this man ner also elim i nates the
pos si bil ity for en try er rors of fix ture off set val ues.
In ge nu ity and a thor ough un der stand ing of your CNC ma chines func tions and fea tures are the keys to
elim i nat ing on-line tasks. By scour ing your CNC con trols pro gram ming man ual, and with theas sis tance
of your ma chine tool build ers ap pli ca tion en gi neers, you may be sur prised at how easy and i n ex pen sive it
can be to elim i nate most on-line tasks - and given un lim ited fi nan cial re sources, any on-line task can be
eliminated.
6.1.7.2. Moving on-line tasks off-line
The sec ond way to re duce setup time is to move the tasks you are cur rently per form ing on-line to off-line.
In stead of per form ing setup tasks while the ma chine is down be tween pro duc tion runs, do as much as you
can up-front, be fore it co mes time to ac tu ally make the next setup. While the task still has to be performed, at least the CNC ma chine tool can still be pro duc ing workpieces. It is not down, wait ing for the
task to be ac com plished.
One ex am ple of mov ing an on-line task off-line (many more will be shown in chap ter eight) is re lated to
tool length compensation on a machining center. If you are currently measuring tool length values
on-line (re gard less of how ef fi cient your tool length mea sur ing tech niques), you can re duce setup time by
mov ing the task of tool length mea sure ment off-line. A tool length mea sur ing gauge (a height gauge, for
ex am ple) can be used to de ter mine the length of each tool. Each tools length can be writ ten down so the
op er a tor can eas ily en ter the tool length value (off set) dur ing the setup. Or better yet, the tool length
mea sur ing gauge can be at tached (via a se rial port) to a per sonal com puter. As soon as a tool length is
mea sured, it can be re corded by the com puter and en tered (au to mat i cally) into a pro gram as part of a tool
off set set ting com mand. Using dis trib u tive nu mer i cal con trol (DNC) tech niques, the offset set ting pro-
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Cy cle Time Reduction
Mod ule seven
7.1. Cy cle time re duc tion
Dur ing our in tro duc tion to setup time re duc tion tech niques, we dis cussed how workpiece quan ti ties dictate the ef fort that goes into the pro cess. As you know, the higher the pro duc tion quan ti ties, the more
elab o rate the pro cess should be. The better the pro cess, the shorter the cy cle time. We cannot stress this
enough. The higher the pro duc tion quan ti ties, the greater the em pha sis that must be placed o n min i mizing cy cle time. How short a given CNC cy cle can be is based pri mar ily on the qual ity of pro c ess ing that
goes into the op er a tion. While we freely ad mit that pro cess ing is the most im por tant facet of the CNC oper a tion, as we said dur ing the in tro duc tion to setup time re duc tion prin ci ples, it is not within the scope of
this text to ad dress pro cess ing re lated is sues. We limit our dis cus sion of cy cle time re d uc tion tech niques
to those that can be ap plied af ter a good pro cess has been de vel oped.
Video tap ing is a very im por tant tech nique in tro duced dur ing our dis cus sion of setup time re duc tion princi ples that ap plies equally well to cy cle time re duc tion. While most CNC cy cles do not re quire the kind of
man ual in ter ven tion as so ci ated with mak ing set ups, you can learn a great deal about how your op er a tors
work and come up with many ideas for im prove ment by study ing your CNC op er a tors cur rent meth ods.
To get a true un der stand ing of what hap pens dur ing each cy cle, be sure you video tape sev eral ac ti va tions
of the CNC cycle. You will need to see the operator do more than simply load and unload a few
workpieces. Be sure you video tape enough to see what hap pens dur ing all tool main te nance (tool re place ment, in sert in dexes, off set set ting, etc.) in or der to find any bot tle-necks in the flow of how pro duction runs.
7.1.1. Cy cle time re duc tion prin ci ples
The prin ci ples of cy cle time re duc tion are quite sim i lar to those for setup time re duc tion. Armed with a
firm un der stand ing of setup time re duc tion prin ci ples, these con cepts should be quite easy to un derstand. You should be able to eas ily fol low along with all pre sen ta tions in this chap ter even if you have not
read the setup time re duc tion pre sen ta tions given in the last two chap ters. How ever, we do elim i nate redun dant pre sen ta tions on top ics al ready dis cussed dur ing setup time re duc tion.
7.1.1.1. Cy cle time de fined
We of fer two def i ni tions of cy cle time. First, many CNC peo ple con sider cy cle time as the in ter val that
passes from a given event in one cy cle to the same event of the next cy cle. For man u ally ac ti vated cy cles, the
ac ti va tion of the CNC pro gram is com monly the event used to mea sure cy cle time. In this case, cy cle time
is con sid ered as the time that passes from one press ing of cy cle start to the next. For com pletely au tomatic cy cles, like those for CNC turn ing cen ters equipped with au to matic workpiece load ing de vices, the
event used to gauge cy cle time might be the clos ing of the chuck jaws to clamp the workpiece.
Mea suring cy cle time based on this el e men tary def i ni tion is very easy. Any one with a stop watch can go
out to the ma chine and sim ply time the cy cle.
While this definition is the one commonly used when discussing cy cle time, re mem ber that there are
other tasks that add to the time it takes to com plete a pro duc tion run that are not in cluded in this sim plistic def i ni tion. These are tasks not nec es sar ily per formed dur ing ev ery cy cle. If the quan tity of workpieces
is large enough, for ex am ple, tool main te nance must be done dur ing the pro duc tion run. This is com monly done on-line, while the ma chine sits idle. Other ex am ples of on-line in ter mit tent tasks in clude the
load ing of bars into bar feed ing turn ing cen ters and check ing workpieces on an sam pling ba sis.
These are at least rel a tively pro duc tive tasks, done to keep pro duc tion flow ing. How ever, there may be
other, far less pro duc tive things go ing on in your CNC en vi ron ment that add to pro duc tion time, yet are
not truly part of your CNC cy cle. If, for ex am ple, a CNC ma chine tool breaks down dur ing a production
run and re quires cor rec tive main te nance, the time it takes to com plete the pro duc tion run i n creases. If
an op er a tor must halt pro duc tion to take a phone call, pro duc tion time in creases. If the ma chine is shut
down dur ing breaks, lunch, or any other per sonal time, pro duc tion time in creases. Truly, any time the
ma chine is down for any rea son dur ing a pro duc tion run in creases the time it takes to com plete the produc tion run and must be con sid ered in the def i ni tion of cy cle time.
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Mod ule Seven
For this rea son, we of fer a much more re al is tic def i ni tion of cy cle time. Cy cle time is the over all length of
time re quired to com plete a pro duc tion run di vided by the num ber of cy cles needed to com plete the pro duction run. Un for tu nately, by this def i ni tion, cy cle time is much more dif fi cult to mea sure. While cer tain
in ter mit tent tasks like tool main te nance can be fac tored in to help cal cu late cy cle time, cer tain things,
like ma chine fail ures, make it im pos si ble to per fectly pre dict cy cle time from one pro duction run to the
next. With this broader def i ni tion, any thing that adds to the time it takes to com plete a pro duc tion run is
con sid ered in the def i ni tion of cy cle time - and is fair game for your cy cle time re duc tion pro gram.
7.1.1.2. Task types for cy cle time re duc tion
As with setup time reduction principles, there are two types of tasks re lated to cy cle time reduction.
On-line tasks are those tasks ac tu ally per formed on the CNC ma chine dur ing the cy cle. In fact, the sum
of on-line tasks is the cy cle time. Off-line tasks are those tasks per formed out side the ma chine tool and inter nal to the ma chin ing cy cle. In or der to fur ther de fine cy cle time, we di vide cy cle time tasks into four
categories.
A CNC ma chine tool is only truly pro duc tive while chips are be ing cut. We call tasks that contrib utes to
ac tu ally ma chin ing chips pro duc tive on-line tasks. The ac tual ma chin ing op er a tions them selves make
up the bulk of pro duc tive on-line tasks and are com monly fully au to matic tasks, com pletely con trolled by
the CNC pro gram.
The sec ond cat e gory of cy cle time re lated tasks is non-productive on-line tasks. These are tasks that oc cur
within the ma chine tool dur ing the cy cle that do not ac tu ally pro duce chips. These can be fully au to matic
tasks or man ual tasks. Ex am ples of fully au to matic non-productive on-line tasks in clude tool chang ing
(by an au to matic tool changer on a ma chin ing cen ter or tur ret in dex on a turn ing cen ter), rapid ap proach
and re tract mo tions, and air cut ting mo tions while tools ap proach sur faces to be ma chined. Ex am ples of
manual non-productive on-line tasks include man ual workpiece loading and unloading, tool main tenance, and any man ual in ter ven tion that oc curs dur ing a pro gram stop (blow ing chips from holes be fore
tap ping, break ing clamps loose for fin ish ing, chang ing chuck ing pres sure on turn ing cen ters be fore finish ing, etc.).
The third cat e gory of tasks re lated to cy cle time is non-productive off-line tasks. These are usu ally manual tasks that the CNC op er a tor per forms to main tain the ma chin ing cy cle while the ma chine is run ning
workpieces. Ex am ples of non-productive off-line tasks in clude off set changes to hold size on t urn ing centers for the pur pose of deal ing with tool wear, workpiece in spec tion, and SPC data re cord ing.
The fourth cat e gory of cy cle time re lated tasks is pro duc tive off-line tasks. These are tasks the CNC op erator performs during the CNC cy cle that ac tu ally fur ther the com ple tion of ma chin ing oper a tions on
workpieces. Sim ple tasks like deburring, clean ing, and pol ish ing as well as more com plex second ary oper a tions fall into this cat e gory.
Just as with setup time, re mem ber that cy cle time is the sum to tal of on-line tasks. Also as with setup
time re duc tion, the goal in cy cle time re duc tion will be to elim i nate on-line tasks, move on-line tasks
off-line, or fa cil i tate on-line tasks.
7.1.1.3. The four ways to re duce cy cle time
While we of fer many cy cle time re duc ing tech niques in this chap ter, our broader in ten tion is for you to be
able to de velop your own cy cle time re duc tion tech niques. Re gard less of how many tech niques we show, it
is likely that your companys spe cial needs will re quire that you de velop many more. As long as you under stand the four ways we show to re duce cy cle time, you should be able to mod ify our given techniques,
or come up with your own, to tackle the chal lenges that await you in your own CNC en vi ron ment.
1.
Im prove the ef fi ciency of pro duc tive on-line tasks
The first gen eral tech nique we of fer is to im prove the ef fi ciency of pro duc tive on-line tasks. Gen erally
speak ing, this means op ti miz ing the CNC pro grams ex e cu tion. In chap ter eight, we of fered three ba sic
steps to pro gram op ti miz ing. First, elim i nate in ef fi cien cies caused by the pro grams basic for mat. Second, op ti mize the cut ting con di tions. And third, op ti mize the ma chin ing pro cess.
How much op ti miz ing you do dur ing a given pro duc tion run must be based on the pro duc tion quantities.
For low pro duc tion quan ti ties, it may be dif fi cult to jus tify any op ti miz ing. For ex ample, if you are only
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run ning a few workpieces with a short cy cle time, it is un likely that any thing can be done to re duce cy cle
time that will shorten the over all pro duc tion run. In this case, mak ing good workpieces may be the only
cri te ria for the pro duc tion run. Maybe the best you can hope for is that your peo ple learn en ough dur ing
this pro duc tion run to im prove cut ting con di tions for fu ture times when the same workpiece (or ma te rial)
must be ma chined.
On the other hand, as pro duc tion quan ti ties grow, op ti miz ing can have a ma jor im pact on the over all produc tion time needed to com plete the job. Say, for in stance, you must ma chine 10,000 workpieces with a
two min ute cy cle. If you come up with an im prove ment that saves but one sec ond per cy cle, your pro duction run will be short ened by over 2.5 hours (10,000 sec onds di vided by 60 is 166.6 min utes, or 2.7 hours).
In this case, over two hours of op ti miz ing time could be jus ti fied be fore pro duc tion is run.
Most CNC pro gram mers would agree that any new CNC pro gram can be im proved upon. How ever, as
hu man be ings, we tend to leave well enough alone. If a CNC pro gram is ma chin ing workpieces in an accept able man ner, it can be dif fi cult to change any thing. You know the say ing, if it isnt broke, dont fix it!
How ever, given this great po ten tial for sav ings, CNC peo ple must avoid the nat u ral ten dency to leave
well enough alone.
2. Min i mize non-productive on-line tasks
Our sec ond gen eral cy cle time re duc tion tech nique is to min i mize non-productive on-line tasks. Re member that these can be man ual tasks or au to matic tasks. Since any thing that hap pens on-line dur ing the
cy cle is fair game, this cat e gory of ten of fers the great est po ten tial for im prov ing cy cle time.
One ex am ple for re duc ing au to matic non-productive time is re lated to tool chang ing on ma chin ing centers. Re gard less of how fast your au to matic tool changer changes tools, tool chang ing is non-productive
on-line time. If mul ti ple workpieces are run dur ing the ma chin ing cy cle, the tool chang ing time can be aver aged over sev eral workpieces. An other non-productive on-line task that of fers a great po ten tial for savings is workpiece load ing. Any thing that can be done to re duce workpiece load ing time (whether man ual
or au to matic) will ef fec tively re duce cy cle time.
3. Move non-productive on-line tasks off-line
The third gen eral tech nique is to move non-productive on-line tasks off line. While this as sumes the cy cle
time is long enough to be per form ing cer tain tasks off-line, any thing that re duces on-line time re duces
over all cy cle time.
Tool main te nance is one prime can di date for this kind of sav ings. If the ma chine is down while a CNC oper a tor per forms ba sic tool main te nance like in dex ing in serts for car bide in sert tool ing, a great deal of produc tion time can be wasted. While this task does not oc cur in ev ery cy cle, when tool main tenance is
per formed, it will add to the length of time re quired to com plete the pro duc tion run and must be con sidered as part of cy cle time. As you will see later in this chap ter, there are sev eral things that can be done to
help an op er a tor per form tool main te nance tasks off-line.
4. Move pro duc tive on-line tasks off-line
An other gen eral tech nique that can save a great deal of pro duc tion time is to move pro duc tive on-line
tasks off-line. This cat e gory is most im por tant with CNC cy cles hav ing ex tremely long cy cle times. As
long as the CNC op er a tor has suf fi cient time dur ing the CNC ma chin ing cy cle, they can perform ma chining op er a tions in ter nal to the CNC op er a tion. This not only keeps the op er a tor busy, over all cy cle time
can be dra mat i cally re duced.
One com mon way com pa nies keep their CNC op er a tors busy is to have them per form ing sec ond a ry machin ing op er a tions on the workpiece be ing ma chined by the CNC ma chine tool. In many CNC envi ronments, for ex am ple, the ma chin ing cen ter op er a tor per forms tap ping op er a tions off-line. Since tap ping
tends to be a trou ble some op er a tion, and since tap ping re quires no great skill or ac cu racy (it can be done
on a sim ple drill press and re quires al most no setup time dur ing change-overs), even an un skilled CNC
op er a tor can per form this sec ond ary op er a tion with a min i mum of train ing. When this tech nique is used,
the over all cy cle time can be re duced by the time it would take the CNC ma chine to per form the tap ping
operations.
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Mod ule Seven
While this is an ex cel lent tech nique that can dra mat i cally re duce cy cle time, keep in mind that the pri ority must be placed on re duc ing cy cle time, not keep ing the op er a tor busy. The sec ond ary o p er a tions must
be well planned in or der to en sure that the op er a tor has time to per form sec ond ary op er ations dur ing the
CNC ma chin ing cy cle and avoid con flicts with the op er a tors other CNC re lated tasks.
If the goal is to sim ply keep the op er a tor busy, it may be wiser to seek an al ter na tive method. In stead of
caus ing the op er a tor to rush through the sec ond ary op er a tions in or der to keep up with the CNC ma chine
tool, have them per form sec ond ary op er a tions on less ur gent workpieces. Or have them per form ing tasks
that re quire less skill, like clean ing, pol ish ing, and deburring.
7.1.1.4. The one-second rule
To stress the im por tance of re duc ing cy cle time and to of fer a sim ple method of cal cu lat ing the po ten tial
sav ings re lated to in cor po rat ing a cy cle time re duc ing tech nique, we of fer this sim plerule-of-thumb. We
will be us ing it through out this chap ter to stress how seem ingly mi nor changes can re sult in dramatic
pro duc tion time sav ings. For ev ery sec ond you can re move from cy cle time, you save 16.6 min utes per
one-thousand cy cles (one-thousand sec onds di vided by sixty). While at first glance this may not sound
like much, you will be sur prised at how fast the sav ings can add up. For ap prox i mat ing pur p oses, you can
round the 16.6 min utes down to a quar ter hour (fif teen min utes). By ap ply ing the one-secondrule, if you
can save but four sec onds per cy cle, you will save over one hour of pro duc tion time per one thou sand cycles.
1.
Other time re lated for mu lae
While we are on the sub ject of time cal cu la tions, there are sev eral other for mu lae that are help ful when
cal cu lat ing a ma chin ing op er a tions in flu ence on cy cle time. We will be us ing them through out this chapter. While they as sume you are work ing in the inch sys tem, sim i lar for mu lae can be de vel o ped for use
with the met ric sys tem.
Time in min utes = length of mo tion in inches di vided by the inches per min ute mo tion rate
One sec ond = 0.01666 min utes
Inches per min ute feedrate = inches per rev o lu tion (IPR) feedrate times rev o lu tions per minute (RPM)
RPM = 3.82 times sur face feet per min ute (SFM) di vided by ma chin ing di am e ter
Though it may be some what ob vi ous to you at this point, keep in mind that feedrate is di rectly pro portional to spin dle speed (in RPM). If you dou ble spin dle speed (and you main tain inches per revolution
feedrate), feedrate will dou ble. For ex am ple, if you wish to ma chine at 0.010 IPR, at 1,000 RPM, your
inches per min ute feedrate will be 10 IPM (0.010 times 1,000). If you dou ble the spin dle speed to 2,000
RPM and main tain 0.010 IPR, feedrate in inches per min ute will in crease to 20 IPM.
More im por tantly, al ways re mem ber that cy cle time is in versely pro por tional to feedrate. If the feedrate
for a given op er a tion is in creased, the cy cle time re quired for the op er a tion will be re d uced in equal proportion.
This knowl edge that feedrate is in versely pro por tional to cy cle time is very help ful when you are ap prox imat ing the im pact chang ing cut ting con di tions will have on cy cle time. Con sider a mill ing op er a tion that
re quires a mo tion dis tance of ten inches. At ten inches per min ute, this op er a tion will take pre cisely one
min ute to com plete (ten inch dis tance di vided by ten inches per min ute). If you dou ble the feedrate to
twenty inches per min ute, the re quired time will be cut in half to thirty sec onds (ten inches of mo tion divided by 20 inches per min ute).
7.1.1.5. How fast can your ma chines rapid?
The rapid rates of todays (es pe cially smaller) CNC ma chines are amaz ingly high. It is not un c om mon, for
in stance, for a small ma chin ing cen ter to have a rapid rates of 1,200 inches per min ute or more. With
these very fast rapid rates, man u fac tur ing peo ple (and es pe cially CNC pro gram mers) tend to ig nore the
im pact rapid move ments have on cy cle time. Al ways re mem ber that rapid move ments do not oc c ur instan ta neously. And dur ing many rapid move ments, the ma chine will never reach its true rapid rate. All
CNC ma chine tools uti lize and ac cel er a tion and de cel er a tion func tion dur ing rapid to pro tect the machines servo drive sys tems. Though this pro tec tion var ies based upon ma chine size, it is un likely, for exam ple, that any CNC ma chine will ever reach its full rapid rate dur ing a small 0.500 in mo tion.
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CNC Concepts, Inc.
Re gard less of how fast your ma chines can rapid, any mo tions that oc cur add to cy cle time. Since rapid
mo tions tend to get over looked when cy cle time re duc tion tech niques are im ple mented, we wish to em ploy the time cal cu la tion for mu lae to dem on strate the im pact of rapid mo tions on cy cle time.
In or der to help you de ter mine the im pact of rapid move ments on your own CNC ma chines, cal cu late how
far the ma chine needs to rapid be fore one sec ond is added to your cy cle time. This dis tance will dif fer from
one ma chine to an other, based on the ma chines rapid rate. Say, for ex am ple, you have a small machining
cen ter with a rapid rate of 1,200 IPM. For this ma chine, one sec ond will be added to cy cle time for ev ery
twenty inches of rapid mo tion (20 di vided by 1,200 equals 0.0167 min utes, which is just slightly more
than one sec ond).
It is not un usual for a ten tool ma chin ing cen ter pro gram to re quire as much as 150 inches of rapid mo tion, even on a rel a tively small ma chine tool. At 1,200 IPM thats about 7.5 sec onds of rapid mo tion per cycle (150 di vided by 1,200 is 0.125 min utes or 7.5 sec onds). In a pro duc tion run of 1,000 workpieces, it
equates to just over two hours of pro duc tion time (7,500 sec onds), just for rapid move ments! R emember,
this cal cu la tion did not even take into ac count the ac cel er a tion and de cel er a tion of the ma chine. In re ality, even more time will be re quired. Also, this cal cu la tion is for one of the fast est rapid rates cur rently
avail able. With older equip ment hav ing slower rapid rates, the im pact of rapid mo tions on cycle time will
be even greater. The to tal rapid time for a ma chine that can only rapid at 400 IPM in the pre vi ous ex ample will be well over six hours!
We urge you to use this tech nique to cal cu late just what im pact your rapid mo tions have on your own
CNC ma chine tools. It should eas ily stress the need to min i mize rapid mo tions when ever pos si ble within
your CNC pro grams.
7.1.2. Re ducing workpiece load ing and un load ing time
As stated, the time it takes to load and un load workpieces fits into the cat e gory of non-productive on-line
cy cle time. With al most all CNC equip ment, re gard less of how workpieces are loaded (man u ally or au tomatically), the machine must be sitting idle during this task. Any technique that reduces on-line
workpiece load ing time will ef fec tively re duce cy cle time. And as with any facet of cy cle time re duc tion,
the higher the pro duc tion quan ti ties, the more im por tant it will be to re duce load ing and u n load ing time.
More and more CNC ma chine tools are be ing equipped with au to matic load ing and un load ing de vices
which elim i nate the CNC op er a tor from the load/un load task. How ever, since these de vices u su ally have
fixed load/un load times (not much can be done to im prove their ef fi ciency), and since the bulk of CNC machines still require at least some operator intervention, we limit our discussions to oper a tor as sisted
workpiece load ing and un load ing.
As with our discussion of setup time reduction principles, anything that can be done to facilitate
non-productive on-line tasks will have an pos i tive im pact on workpiece load ing time. Steps should be
taken to make it as easy as pos si ble for the CNC op er a tor to ef fi ciently com plete the workpiece load ing
pro cess. Also as with our dis cus sion of setup time re duc tion prin ci ples, one ex cel lent way to brain storm
for workpiece load ing and un load ing ideas is to video tape the workpiece load ing pro cess.
Cer tain en hance ments to workpiece load ing/un load ing should be easy to spot. For ex am ple, workpieces
run on CNC ma chine tools can be very heavy. This, com bined with the fact that CNC op er a tors will become fa tigued dur ing a days work (and prone to in jury), make it es sen tial that ev ery step be taken to let
the op er a tor move heavy workpieces safely and ef fi ciently. Over head and boom cranes should b e used for
heavy workpieces. Even with these de vices to as sist them, workpiece load ing/un load ing can still be dif ficult. Is your op er a tor strug gling with the cum ber some straps used with most cranes? Per haps a magnetic at tach ment will make the task eas ier to com plete. Is the headstock of the ma chine (or any other
ma chine com po nent) in ter fer ing with the op er a tors abil ity to use the crane? Per haps the pro gram can be
changed to po si tion the ma chines axes such that in ter fer ence prob lems are elim i nated. Any num ber of
pos si ble im prove ments can be made to fa cil i tate the op er a tors abil ity to per form the load/un load task. In
this sec tion, we of fer a few sug ges tions.
7.1.2.1. Turn ing cen ter sug ges tions
The dif fi cul ties as so ci ated with turn ing cen ter workpiece load ing vary dra mat i cally based on the ma chines ap pli ca tion. Gen erally speak ing, due to the na ture of the work hold ing de vice (commonly an au to-
CNC Concepts, Inc.
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Probing Devices
Mod ule eight
8.1. Probing devices
There are a va ri ety of probes avail able for use with CNC ma chine tools. Most are touch probes, mean ing
they must con tact a sur face be fore they trig ger. Though some sense con duc tiv ity, most touch probes
must ac tu ally de flect a small amount in or der to trig ger. In ad di tion to touch probes, a grow ing num ber of
laser probes are becoming available. The bulk of this presentation deals with deflection-type touch
probes.
First we’ll in tro duce the ba sic con cepts be hind how prob ing is done. As you will see, the act of prob ing remains very much the same re gard less of probe type or ap pli ca tion. For prob ing nov ices, you will see that
probes are just an other kind of tool used by a CNC ma chine tool, and this dis cus sion should take the mystery out of how probes ac com plish their re quired tasks.
We also in tro duce the three most pop u lar touch probe types. All are con tact sen si tive, mean ing they are
trig gered by the de flec tion of the sty lus within the probe. Most cur rent probes are very ac c u rate, re quiring but a very tiny amount of de flec tion to trig ger. Though the mech a nisms used to de tect deflec tion vary
from one probe man u fac turer to an other, sev eral probe man u fac tur ers claim that their probes will trigger within twenty mil lionths of an inch of de flec tion (0.00002 in). This chap ter will sim plyin tro duce the
probe types. In chap ter two, we will in tro duce ap pli ca tions for each type.
8.1.1. The con cept of prob ing
We in ten tion ally keep this dis cus sion very ba sic, and speak in gen er al i ties to avoid be c om ing overly techni cal (a probe spe cial ist may find these dis cus sions overly ba sic). Our in ten tion is sim p ly to take the mystery out of how prob ing sys tems (of any kind) work. Rest as sured that fu ture pre sen ta tions will ex plain
prob ing in func tions much greater de tail.
From your man ual pro gram ming ex pe ri ence, you know you have the abil ity through pro grammed commands to make the ma chine per form many func tions. You can start the spin dle at the de sired speed, turn
on the cool ant, rapid a tool into po si tion, and be gin ma chin ing at a de sired feedrate. In d eed, true ma chining cen ters and turn ing cen ters al low you con trol of vir tu ally any thing of which you need c on trol through
pro grammed com mands.
For as pow er ful and func tional as your man ual pro gram ming com mands are, you must un der stand that
they are in suf fi cient for han dling even the most ba sic probe ap pli ca tions. Stated an other way, we need
ad di tional pro gram ming ca pa bil i ties (more than are al lowed in most man ual CNC pro gram ming lan guages) in or der to pro gram prob ing sys tems. This is why para met ric pro gram ming is re quired. The specific version of parametric programming we use for examples throughout this discussion is Fanuc’s
cus tom macro ver sion B, the most pop u lar ver sion of para met ric pro gram ming used by sev era l CNC control man u fac tur ers. Note that we de vote an en tire mod ule of this course to para met ric pro gram ming. In
this dis cus sion, we’ll sim ply in tro duce those fea tures of para met ric pro gram ming that are re quired for
probing.
8.1.1.1. Cus tom macro B func tions needed for prob ing
Here are some of the func tions cus tom macro B al lows that are re quired for prob ing which are not pos sible through ba sic man ual pro gram ming.
1. Ac cess to ma chine po si tion af ter prob ing
The most im por tant prob ing re lated func tion cus tom macro B al lows is the abil ity to at tain the ma chine’s
po si tion af ter prob ing takes place. In deed, the probe would be worth less with out this ability. Though
how the ma chine’s po si tion af ter prob ing is used will vary from one ap pli ca tion to an other, this abil ity is
at the very core of any prob ing sys tem.
2. Variables
Many prob ing ap pli ca tions re quire mul ti ple touches of the probe. Com par i sons or cal cu la tions in volv ing
the var i ous ma chine po si tions af ter prob ing will com monly be re quired, mean ing you must have a place to
store ma chine po si tions for fu ture use. Among many other things, vari ables are used for thispurpose.
CNC Concepts, Inc.
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Mod ule Eight
3.
Arith me tic ca pa bil i ties
As men tioned, there will com monly be cal cu la tions to make in prob ing pro grams. You will see (in a fu ture
mod ule) that just about any thing that can be done on a sci en tific cal cu la tor can be done with a cus tom
macro B pro gram.
4.
Ac cess to off sets and other ma chine func tions
Many prob ing ap pli ca tions re quire ac cess to tool off sets. A ma chin ing cen ter prob ing sys tem de signed to
mea sure tool length com pen sa tion val ues, for ex am ple, must have the abil ity to ac tu ally set a tool off set
once a tool’s length com pen sa tion value is de ter mined. You will see that all tool off sets are ac ces si ble
through cus tom macro B com mands (tool off sets, fix ture off sets, wear off sets, ge om e try off sets, work shift
off set, etc.).
Probing sys tems also re quire ac cess to other ma chine func tions. For ex am ple, you will learn that prob ing
must be done at a con sis tent feedrate. If an op er a tor has placed the feedrate over ride switch at some thing
other than one hun dred per cent, it could re sult in in ac cu rate prob ing. For this rea son, cus tom macro B
al lows the probe pro gram mer to dis able feedrate over ride (tem po rarily) dur ing the prob ing cy cle. Many
other ma chine func tions are ac ces si ble with cus tom macro B.
5.
Logic
Many prob ing ap pli ca tions re quire the prob ing pro gram to make de ci sions and be have dif fer ently based
on the re sult of each de ci sion. For ex am ple, a pro gram mer de vel op ing a prob ing pro gram that mea sures
the width of a slot will have to plan on sev eral con tin gen cies. If, for ex am ple, the mea sured slot is too narrow, it may be the pro gram mer’s de sire to ad just an off set (au to mat i cally) and re-machine with the tool.
If the slot is too wide, pos si bly the workpiece is now scrap. In this case, an alarm may be sounded by the
prob ing pro gram to stop fur ther ma chin ing. If the slot is within its tol er ance band but not pre cisely at its
mean value, an off set could be ad justed ac cord ingly so the slot in the next workpiece is ma chined perfectly. The ma chine could then con tinue in the nor mal man ner. This is but one ex am ple of the many
times when logic com mands must be used in the prob ing pro gram.
8.1.2. The probe it self
Al ways re mem ber that con tact-triggered touch probes are noth ing more than highly ac cu rate contact
switches. As men tioned ear lier, all probes dis cussed in this text are touch probes, mean ing they re quire
but a tiny amount of de flec tion to trig ger. When they trig ger dur ing a prob ing com mand (commonly
within twenty mil lionths of an inch de flec tion), a sig nal is sent to the CNC con trol which halts axis motion. This sig nal tells the con trol to at tain the ma chine’s po si tion as close to the in stant in time the probe
made con tact as pos si ble. As stated ear lier, this po si tion (in all axes) is ac ces si ble to the prob ing pro gram.
This un der stand ing that probes sim ply tell the CNC con trol to at tain the ma chine’s po si tion, cou pled
with un der stand ing the ad di tional pro gram ming func tions needed for prob ing that are available through
cus tom macro B should go a long way to ward help ing you un der stand what goes on in any prob ing system, re gard less of the sys tem’s com plex ity.
8.1.2.1. Probe types
Again, this text will dis cuss the three most pop u lar forms of touch probes used with CNC ma chin ing centers and turn ing cen ters.
1.
The five di rec tion touch probe
This kind of probe can be mounted in the spin dle of a ma chin ing cen ter or in the tur ret of a turn ing cen ter.
As the name im plies, it al lows de tec tion of de flec tion for five mo tion di rec tions. When mounted in the
spin dle of a ma chin ing cen ter, de flec tion can be de tected dur ing X+, X-, Y+, Y-, and Z- mov e ments. The
next draw ing shows this type of probe.
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CNC Concepts, Inc.
Probing Devices
Di rec tions of prob ing for a five di rec tion touch probe mounted held in the spin dle of a ma chin ing cen ter.
Probes used in this man ner are com monly called spin dle probes. Through out this dis cus sion, we place a
heavy em pha sis on the pro gram ming of spin dle probes for three rea sons. First, they com monly re quire
the most in the way of pro gram ming from end us ers. Other probe types typ i cally re quire very lit tle in the
way of spe cial pro gram ming. Sec ond, they tend to be the most com pli cated probes with which to work. If
you can un der stand the pro gram ming of spin dle probes, you will be able to eas ily adapt what you know to
spe cial pro gram ming for other probe types. Third, of the probe types, spin dle probes al low the most diver si fied ap pli ca tions. Other probe types com monly have but one spe cific pur pose. Once they are initially programmed for their specific application (commonly by the machine tool builder or probe
man u fac turer), there will be lit tle, if any, need for fur ther pro gram ming.
The five di rec tion touch probe can also be mounted in the tur ret of a turn ing cen ter. How ever, since most
turn ing cen ters only al low the tur ret to move in two di rec tions, two di rec tions of prob ing are usu ally lost
when the five di rec tion touch probe is mounted in the tur ret of a turn ing cen ter. The ex ception to this
state ment is the turn ing cen ter hav ing a Y axis. Turn ing cen ters that have X, Y, and Z axes al low the five
di rec tion touch probe to de tect de flec tion dur ing mo tions in all five mo tion di rec tions. The next draw ing
shows this kind of probe mounted in a turn ing cen ter’s tur ret.
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Page 8-3
Mod ule Eight
Di rec tions of prob ing for a five di rec tion touch probe when mounted in the tur ret of a two axis turn ing cen ter.
Note that the pre vi ous draw ing shows the most com mon type of (straight) sty lus. For a two axis turn ing
cen ter, it al lows de tec tion of de flec tion while mov ing in the X+, X-, and Z- di rec tions. De pending upon the
ap pli ca tion, how ever, it is pos si ble to de sign the sty lus to probe in dif fer ent di rec tions. For ex am ple, if the
sty lus for the probe shown in the pre vi ous draw ing is bent ninety de grees, or if the touch probe is mounted
in an X axis tool holder, it will al low prob ing in X-, Z+, and Z-.
2.
Spin dle probes with only two prob ing di rec tions
While it may sound like a bit of a con tra dic tion, it is pos si ble that a probe placed into the spin dle of a machin ing cen ters may re quire only two di rec tions of prob ing. If the ma chin ing cen ter al lows the pre cise
spin dle ori en ta tion to (at least four) an gu lar po si tions, the probe sty lus can be ro tated for prob ing in the
X+, X-, Y+, and Y- di rec tions. This means only one di rec tion of prob ing is needed to probe in four dif fer ent
di rec tions. Keep in mind that we are not talk ing about the sim ple spin dle ori en ta tion com m and (M19)
used in con junc tion with the au to matic tool changer. While this com mand is also used in con junction
with five di rec tion spin dle probes (more on why later), the M19 spin dle ori ent com mand will r e sult in but
one an gu lar po si tion.
Com mon pro gram ming meth ods
Most probe man u fac tur ers will pro vide their cus tom ers with a set of canned prob ing rou tines they perceive their cus tom ers to need (much like the canned cy cles used for hole ma chin ing op er a tions). These
canned rou tines are usu ally very easy to use, and in some cases, may be suf fi cient to meet theprobe user’s
needs. How ever, keep in mind that ap pli ca tions for five di rec tion touch probes are very di verse. It is
likely that no two CNC us ers will have iden ti cal needs. For this rea son, five di rec tion touch probe us ers
should strive to gain the knowl edge and abil ity to de velop their own cus tom prob ing rou tines. Also for
this rea son, al most all five di rec tion touch probes are driven with (very flex i ble) para met ric pro gramming, com monly cus tom macro B.
3.
Tool length mea sur ing probes
There are ac tu ally two vari a tions of tool length mea sur ing probes. First, this form of probe is used for machin ing cen ter ap pli ca tions to mea sure tool off set val ues to be used with tool length com p en sa tion. If
used only to find tool length val ues, only one di rec tion of prob ing is re quired (Z-). The next draw ing shows
this kind of probe.
Tool length mea sur ing probe shown mounted to ta ble of a ver ti cal ma chin ing cen ter.
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CNC Concepts, Inc.
Probing Devices
With the probe placed some where in the ma chine’s work en ve lope (pos si bly mounted right to thema chine
ta ble), a tool tip is brought into con tact with the probe sty lus to de ter mine the tool length compensation
off set value. More on how this kind of probe works as we pres ent the ap pli ca tions for prob ing a lit tle later
in this chap ter.
The sec ond vari a tion of this kind of probe is that it may be ad di tion ally de signed to mea sure cut ter ra dius
com pen sa tion off set val ues. If this is the case, at least one more di rec tion of prob ing is nec es sary (X+, X-,
Y+, or Y-). Of course, cut ter ra dius com pen sa tion is only re quired for mill ing cut ters, and only when milling on the pe riph ery of the cut ter (as when con tour mill ing), mean ing this kind of prob ing is only used
with mill ing cut ters.
In or der to come up with an ac cu rate cut ter ra dius com pen sa tion off set value, most probe m anufacturers
rec om mend that the spin dle be started prior to mea sur ing the cut ter’s ra dius. To keep from ac tu ally machin ing the probe sty lus, most rec om mend that the spin dle be started in re verse (M04 for right hand milling cut ters).
Mount ing to the ma chine
The method by which tool length mea sur ing probes are made avail able to the ma chine tool it self var ies
among ma chine tool build ers and probe man u fac tur ers. Older tool length mea sur ing probes must be
phys i cally mounted to the ta ble of the ma chine tool (man u ally) ev ery time tool length mea sure ments are
re quired, mak ing them some what cum ber some to work with. (This type of probe is shown in the t wo previous draw ings.) Any time saved with tool length mea sure ment is lost when you con sider the time it
takes to mount the probe to the ta ble and re move it when fin ished. The ex cep tion to this state ment is a
ver ti cal ma chin ing cen ter that has am ple room on the ta ble for both the workholding setup and the tool
length mea sur ing probe. Since ver ti cal ma chin ing cen ters gen er ally have more ta ble space than hori zontals, older tool length mea sur ing probes are ap plied more com monly to ver ti cal ma chin ing cen ters than to
hor i zon tal ma chin ing cen ters.
Newer tool length mea sur ing probes swing into po si tion only when needed and swing out of the way when
not. Com monly, two M codes con trol the func tion of the swing arm. This more con ve nient form of tool
length mea sur ing probe over comes the lim i ta tions of the older style just dis cussed and is be com ing pop ular among probe man u fac tur ers and ma chine tool build ers.
Tool break age de tec tion
Though it is not the pri mary pur pose for this kind of probe, a tool length mea sur ing probe can be used as
one form of tool breakage de tec tion sys tem. This kind of tool break age de tec tion works best for tools
whose lengths change dra mat i cally if bro ken (like drills, taps, ream ers, and end mills). If f or ex am ple, it
is sus pected that a tool has bro ken (pos si bly by an out-of-tolerance mea sure ment taken by a spin dle probe
performing in-process gauging), the tool can be brought into contact with the tool length measur ing
probe. Its cur rent length can be com pared to its orig i nal length. If its cur rent length is sub stan tially less
than its orig i nal length, it can be as sumed that the tool has bro ken.
Com mon pro gram ming meth ods
Be cause they also re quire a fair amount of flex i bil ity, most tool length mea sur ing probes are also pro grammed ex clu sively with cus tom macro B com mands. Most probe man u fac tur ers will sup ply a set of
canned rou tines for the pur pose of mea sur ing tool length and cut ter ra dius com pen sa tion val ues. These
canned rou tines are usu ally quite easy to use and will usu ally come much closer to com pletely matching
the probe user’s needs than stan dard pro grams pro vided with five di rec tion touch probes.
How ever, keep in mind that there are two ways of us ing tool length com pen sa tion. With one method, the
length of the tool is stored as the off set value. With the sec ond method, the dis tance from the tool tip down
to the Z axis pro gram zero point is stored as the off set value. We pre fer the first method (tool length is offset value) since, among other things, it al lows tool length com pen sa tion val ues to be mea sured off-line,
and may pos si bly elim i nate the need for on-line tool length mea sur ing with the tool length measuring
probe when there is am ple time dur ing the cur rent pro duc tion run to be as sem bling and mea sur ing cutting tools needed in the next job.
CNC Concepts, Inc.
Page 8-5
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Finally, we discuss the importance of value
added principles in the CNC environment.
J #2: Review of CNC basics (346 slides)
Since you won’t have control of how much
previous experience your students have (aside
from setting some pretty broad prerequisites),
you’ll want to make sure that they have a good
grasp of basic CNC principles before digging in to
more advanced topics. Again, many students
coming to this course will be (for the most part)
self-taught. It’s likely that they’ve missed out on
some important basic concepts and techniques.
In the advance courses I’ve taught myself, I’m
always surprised at how often a so-called expert
is unfamiliar with a very basic CNC feature or
function.
This module allows you to review the basics
using our proven key concepts approach. (This
is the same approach used in our basic CNC
course curriculums.) There are ten key concepts.
We begin each key concept by introducing the
reasoning behind the key concept. Then we
address how the key concept applies to
machining centers and then to turning centers.
Again, this is a review. Students should be quite
familiar with the presentation –and if they are –
you’ll be able to buzz through quite quickly. But,
if they’re questioning each step along the way, it
should be taken as a signal that more basic
training is needed.
J #3: Advanced implications of basic
features (911 slides)
Many CNC features have multiple uses. But
most basic CNC courses introduce only the most
important use. Additionally, most basic courses
don’t show all implications related to how a given
feature can be best used to meet the company’s
specific applications. If it’s a basic function, and if
it’s not commonly addressed in a basic CNC
course, it’s fair game in this module.
Included in this lengthy module (the longest of the
course) are presentations on parameters, N
words, G codes, M codes, and other CNC words.
We go over each code, one by one, and in
numerical order
We also discuss advanced applications for tool
offsets, fixture offsets, and wear offsets. Since
we show so many alternative methods of
handling basic CNC functions, there’s plenty of
audio guidance during the slide show to help
you prepare to teach this module.
J #4: Advanced CNC features,
functions, & concepts (432 slides)
There are many CNC features that are not
addressed in basic courses. Admittedly, many
of these features will not be of interest to a
given CNC user. However, this module gives
you the presentation material you need to
discuss features like advanced interpolation
types (helical, cylindrical, polar coordinate, and
nurbs), scaling, mirror image, coordinate
rotation, and three dimensional coordinate
conversion. We also include presentations on
certain machine accessories like bar feeders,
index chucks, U axis, and part catchers.
Finally, we provide materials for teaching some
important CNC concepts like tool life
management, qualifying CNC programs, and
appropriate documentation.
J #5: Parametric programming (556)
We’ve often said that parametric programming
is CNC’s best kept secret. There are still many
in the industry that don’t know what it is, let
alone how to take full advantage of it. These
materials allow you to dive into parametric
programming as deep as you want to go. We
stress Fanuc ’s version of parametric
programming – custom macro B (the most
popular version).
If you just want to present a cursory view of
what it is, you’ll just be acquainting students
with it’s applications and basic features. This
can be done quite quickly. But if you want to
present a full course, these materials still allow
you to do so. With limited time for practice
(practice exercises with answers are also
provided), this full course can be completed in
about 16 hours.
J #6: Setup time reduction (295 slides)
All CNC using companies are concerned with
how long their machines are down between
production runs. This module lets you first
present the principles of setup time reduction
(that can be applied to any form of production
equipment). We then offer specific CNCrelated techniques to improving setup time in
the same order setups are made (tear down,
work holding setup, cutting tools, program zero
assignment, program loading, program
verification, and first workpiece inspection).
CNC Concepts, Inc., 44 Little Cahill Road, Cary, IL 60013 ph:847-639-8847 fax:847-639-8857 internet:www.cncci.com
J #7: Cycle time reduction (411 slides)
Instructor’s outline
All CNC using companies are concerned with
how long it takes to complete their production
runs. As with setup time reduction, this module
lets you first present the principles of cycle time
reduction. We then offer specific techniques to
reducing cycle time in four areas, workpiece
load/unload, program execution time, tool
maintenance, and preventive maintenance.
The outline serves three purposes. First, it lets
you know exactly what is presented in each
module. You’ll be able to quickly see what’s
there. Second, it shows the slide number for
each topic, making it easy to find slides as you
move around in each slide show. For most
topics, it also includes student manual page
numbers so you can reference what the student
will see as you give your presentation. Note
that this will help you read up on topics you are
unfamiliar with.
J #8: Spindle probe programming
(519 slides)
Actually, the student manual includes
discussions on several types of probes (spindle
probes, tool touch-off probes, and tool length
measuring probes). However, the slide
presentation is limited to spindle probes.
Admittedly, most spindle probe uses depend
solely on the probing programs supplied by the
probe manufacturer. Only a small percentage
of probe-using companies develop their own
probing programs. For this reason, most
students may not be very interested in learning
how probes are programmed. You may elect
to simply introduce the basics. But if you do
need to teach a full course on spindle probe
programming, these materials let you do so.
Presentations include introduction to probe
programming, applications for probing, how the
probe works, calibration techniques, and
writing spindle probe programs.
Instructor materials:
Microsoft PowerPoint slide presentations
PowerPoint is fast becoming the presentation
software of choice by most presenters. These
presentations total over 3,000 slides to provide
your visuals for the entire course. Note that
they’re developed in PowerPoint 97 (which is
part of Microsoft Office 2000). These
presentations are included on a cd and most
include audio narrations. There are ten slide
presentations included on the cd-rom. Each is
locally named from INTRODUCTION.PPT
through MODULE 8_SPINDLE PROBES.PPT.
These slide presentations can be accessed
right from the cd-rom drive or if your hard drive
has the room, you can copy them to your
computer’s hard drive (there’s over 300 megs of
data).
Each slide includes a visual (in the form of a
book icon) that lets students know the page
number in the student manual that is currently
being discussed.
Guidance during slide shows
Most slide shows includes audio narrations (we
call guidance) to help you understand how to
make your presentations. Note that these
narrations are not intended for your students.
Each is directed at an instructor getting ready to
teach the course (they help with preparation). A
special icon on selected slides can be activated
to play the related narration.
Microsoft PowerPoint Viewer
Though we highly recommend that you have
the actual PowerPoint software, we do include
the PowerPoint Viewer. It does allow you to
display the slide shows, but you’ll have no way
to modify them. Additionally, the slide shows
are quite long (most over 300 slides).
PowerPoint Viewer does not allow you to move
around in the slide show nearly as easily as the
actual PowerPoint software does.
Workbook and answer book for
Parametric Programming module
Since this portion of the course requires
practice to master, we provide you with a way of
printing exercises and programming activities
for students to do during this module. It can be
used as homework or done during class. We
also provide you with the ability to print the
answer book.
Ability to print slide show hard copy
PowerPoint allows you to print a hard copy of
each slide show (Microsoft calls this printing
handouts). This may help you prepare if you
don’t always have a computer available. You
can include 4, 6, or 8 slides per page. Even so,
there are over 3,000 slides. Be ready for a lot
of printing!
Promotional materials
We’ve even included a brochure that you can
use to help you promote this course. It’s in the
“promotions ” folder of the cd rom. It’s in
PowerPoint format, so you can easily modify
anything you want! Note that there is space to
include your school’s registration information
(logo, phone number, fax number, etc.).
Free phone assistance
Again, there’s a lot of information in this
curriculum. If you have questions about any
topic while your preparing to teach the course,
we welcome your phone calls (847-639-8847).
Or email us at [email protected].
644 page student manual
This extremely comprehensive manual follows
along with your presentation each step of the
way, and again, the slide presentations
reference page numbers throughout the course.
It will make for excellent homework reading
assignments and it’s an excellent way for
students to go back and review material once
the course is finished.
What you’ll still need
In order to show the PowerPoint slide
presentations to a group of people, you need
the following items.
A computer with Windows 98 (or higher) Just
about any current model computer with a cdrom drive will work. For best results, Pentium
class is recommended (minimum 64 megs
internal). If using a desktop computer, you can
easily watch the monitor of the computer (facing
your audience) to see the slide show as slides
are displayed behind you by the projection
system. Since the left mouse button advances
the slides, you even have a remote slide
advance button (as is commonly used with a 35
mm slide projector).
If portability is an issue, keep in mind that many
of the notebooks and sub-notebooks have
ample power to run the presentation software.
However, be careful in your selection. Many
notebooks do not allow you to send data out
through the VGA port and see the slide show on
the LCD screen of the notebook at the same
time. Without this ability, you may have to turn
around to see your slides, which can be
distracting to your audience. Also, for maximum
flexibility, look for a laptop that has the TV-OUT
feature. This lets you send composite video to
any television that has a TV-IN port with a simple
RCA cable.
Microsoft PowerPoint 97 Software (or above)
Though you can display all presentations with
PowerPoint Viewer (included with this
curriculum), you will need Microsoft PowerPoint if
you intend to modify the slide shows.
PowerPoint 97 also makes it much easier to get
around in the slide shows than the viewer. We
highly recommend that you have this ability.
A way of displaying the screen show - You
have several alternatives in this regard. First,
many schools already have a projection system
that can display information from a personal
computer. Basically, anything that can be shown
on the computer screen can be displayed
through the projection system. Second, and
especially if price is a concern, you can use a
simple scan converter (about $200.00 - $300.00)
and display your screen show on any television
that has a video in connector (as most do). Note
that many laptops are now coming with a TVOUT port, having this scan converter built in to
the computer.
A note about the students you’ll attract
Remember that your attendees will have
(possibly extensive) CNC experience. I’ve found
that most catch right on to the presentations
being made, even for those topics that they’ve
never been exposed to. Frankly speaking, most
aren’t interested in a grade at all - they ’re
interested in learning things that can be applied
immediately in their shops. When they latch on
to an idea that will help them, they’ll stick with it
until they figure it out! For this reason, we
minimize the amount of practice assigned in this
course. With the exception of the parametric
programming module, it’s mostly lecture.
Be sure to take advantage of your students ’
strong points. As you present the course, solicit
ideas and comments each step along the way.
We encourage student participation quite often
during the slide presentations. The more you
can get people to contribute during the class, the
better the class will be. And you’ll be able to
collect ideas for future classes!
Free with initial textbook order!
Not only will you be teaching with the best stateof-the-art CNC curriculums in the industry, you’ll
be doing so free of charge! All we ask is that
your school bookstore buys the student manuals
from us! With an initial order of just 20 manuals,
we’ll ship the instructor’s materials free of
charge! All instructor materials (slide shows,
PowerPoint Viewer, instructors manual, and
Adobe Acrobat Reader to view/print the manual)
come on one cd-rom disk.
Our net price to your school (or bookstore) for
manuals is $95.00 each. Suggested retail price
is $120.00 each. Future orders can be in any
quantity. This cost will be recovered, of course,
as students enroll in your classes and buy the
manuals. In essence, your first 20 students will
be paying for the curriculum!

MAXCNCSAM - 2.14 mb

Transcription

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