Large Capacity Extrusion Technology for the Next Decade

September 26-28, 2007 – Boston, MA
Large Capacity Extrusion Technology for the Next Decade
Tom Brown
Director of Sales & Marketing
Cincinnati Milacron Extrusion Systems Business
Large Capacity Extrusion Technology for the Next Decade
September 26-28, 2007 – Boston, MA
The Trend !
FASTER!!!
1400 RPM!
700 RPM
5000 Pounds/Hr
1000 Pounds /Hr
1500 Pounds/Hr
3000 Pounds/Hr
750 RPM
1750 RPM
150 Amps
350 Amps
Drivers for Large Diameter Extruders
September 26-28, 2007 – Boston, MA
‰ Higher Throughput Rates
‰ Product Changeover Time
‰ Optimal Efficiency
9 Uptime
9 Yield Rate
9 Minimal Scrap
‰ Energy Savings
‰ Environmental
‰ Quality & Consistency of Extruded part
‰ Raw Material Cost & Weight Savings
9 Gravimetric Feeding
9 Foam
9 Coextrusion Processes
‰ Ability to Cool and Pack
Applications
September 26-28, 2007 – Boston, MA
GLOBAL USAGE OF PLASTIC PIPE WILL GROW 6.8% ANNUALLY... (1)
‰ This will take usage to 7.3 billion meters (24 billion ft) by 2010
‰ The most important factors in this impressive growth rate are:
9 Growth in plastic pipe for the natural gas industry and the
telecommunications industry
9 Infrastructure improvements in emerging countries will aid
growth, especially for plastic pipe for:
¾Drinking water
¾Sewage
¾Drainage
‰ PVC pipe will enjoy the greatest growth
(1) Source: Global Industry Analysts Consultancy
September 26-28, 2007 – Boston, MA
Pipe
Diamond Plastics Corporation
140mm Parallel Twin for Large Diameter Rigid PVC Pipe
September 26-28, 2007 – Boston, MA
WPC Decking & Railing
86mm Conical Twin & 2” Single Screw for Co-Extruded PVC based WPC
Hand Rail System
September 26-28, 2007 – Boston, MA
Coextrusion Systems for Vinyl Fence (140mm Parallel Twin with
Two 55mm Conical Coextruders)
Vinyl Fence
September 26-28, 2007 – Boston, MA
Foamed & Homogeneous Rigid PVC Sheet
140mm Parallel Twin Screw for 48” wide and up to 25mm Thick
Foamed Rigid PVC Sheet
Extruders & Extrusion Systems
September 26-28, 2007 – Boston, MA
Dry Blend from Upstream Material
Handling and Blending System
Basic Components of an Extrusion Line
Pipe
Profile
Sheet
Downstream System
Coex
(As rate increases, becomes longer or dual or both)
Feeder
Die
Collection
Dump Table
Stacking Table
Pipe Beller
Coiler
Saw
Puller
Calibration
Vacuum
Calibration
Table
Drive
System
Twin Screw
Single Screw
Vacuum Spray
Tank
Water Spray
Tank
Sheet Roll
Stack
Source: Zeus Industrial Products
Extruder
Primary Components & Variables:
9 Raw Materials
9 Upstream Material Handling & Blending
System
9 Extruder
9 Tooling
9 Downstream System
Pipe, Profile & Sheet Extrusion Systems
September 26-28, 2007 – Boston, MA
Comparison of Conical & Parallel Twins
September 26-28, 2007 – Boston, MA
CONICAL
Application Versatility – Low to Mid Range Rate
Natural Compression – Large vol. to small vol.
Fixed L/D due to cone angle
High surface area in feed zone for heat transmission
Tungsten Clad Barrel – Excellent Life/Difficult to rebuild
Screws can be rebuilt with Tungsten or Molybdenum
PARALLEL
Application Versatility – Mid to High Range Rate
Can lengthen L/D for process versatility
Low process temps over longer L/D for consistent melt temp
Consistent melt flow, screw tips into die
Bimetallic barrels can be re-lined
Screws can be rebuilt with Tungsten or Molybdenum
Conical Twin Screws
(1)
– Range of Technology
September 26-28, 2007 – Boston, MA
Front Dia. (2)
Range (mm)
Flight Length
(D) (3)
Output
Range (lbs/hr)
HP
Application
35 – 39
23 – 24
Up to 264
13 – 20
Profile, WPC, Coex
40 – 54
22 – 24
Up to 500
17 – 41
Profile, Pipe, Coex
55 – 63
22 – 23
Up to 700
40 – 50
Profile, Pipe, Fence,
Siding, WPC, Coex
65 – 72
22 – 24
Up to 1,210
50 – 53
Profile, Pipe, Fence,
Siding, WPC, Coex
80 – 86
23 – 27
Up to 2,000
75 – 125
Profile, Pipe, Sheet,
Fence, Siding, WPC
92 – 96
27 – 30
Up to 2,800
150 - 200
Pipe, Sheet, Siding,
WPC, Pelletizing
(1)
Counter-Rotating Twin Screw Extruders
(2)
Sources: Am. Maplan; Cincinnati Extrusion; Cincinnati
Milacron; Davis-Standard; Krauss-Maffei; Theysohn
(3)
Based on front (discharge) diameter
96mm Conical Twin for WPC Deck Board
Parallel Twin Screws
(1)
– Range of Technology
September 26-28, 2007 – Boston, MA
Diameter (2)
Range (mm)
L/D
Output
Range (lbs/hr)
HP
Application
72 – 88
23 – 28
484 – 1078
32 – 68
Profile, Pipe
90 – 98
26 – 36
748 – 1650
50 – 104
Profile, Pipe, Fence,
Siding Coex
100 – 110
21 – 26
781 – 1800
55 – 125
Profile, Pipe, Fence,
Siding
114 – 118
26 – 36
1210 – 2420
89 – 156
Profile, Pipe, Fence,
Siding
128 – 140
26 – 33
1386 – 3600
123 – 250
Pipe, Sheet, Fence,
Siding, WPC
164 – 173
22.5 – 28
4180 – 5000
218 - 311
Pipe, Sheet
(1)
Counter-Rotating Twin Screw Extruders
(2)
Sources: Am. Maplan; Cincinnati Extrusion; Cincinnati
Milacron; Davis-Standard; Krauss-Maffei; Theysohn
172mm 26:1 L/D Parallel Twin for RPVC Sheet
Gains In “Processing” – Not Just the Extruder
September 26-28, 2007 – Boston, MA
‰ Improvements in Formulations
‰ Improvements in Tooling Designs
‰ Improvements in Downstream Capability
‰ Improvements in Gear Box Designs/Thrust
Bearings
‰ Improvements in Screw Designs
‰ Ability to add Tungsten Carbide to Screws &
Barrel
PVC Twin Screw Matrix
September 26-28, 2007 – Boston, MA
Blend Plant
Compound
Formulation
Good
Good
Extrusion
Conditions
Final Product
Good
Excellent
Poor
OK
Good
Marginal
Poor
Scrap
Good
OK/Marginal
Poor
Scrap
Good
OK/Marginal
Poor
Scrap
Poor
Good
Poor
Poor
Designing The “Next Size Up” Extruder
September 26-28, 2007 – Boston, MA
What Determines Output Rate:
‰ Diameter of Screws
‰ Centerline Spacing of Gear Box Shafts
‰ RPM of Screws
‰ Geometry of the Screw Design
Parallel Twin Screw Design
September 26-28, 2007 – Boston, MA
High Surface Area
Conveying
Mixing
Feed/Conveying
Pre-Heat #1
Zone Starts: (3)
(6)
Melting
Pre-Compression
(3)
Melting &
Mixing
Venting
Compression
(2)
Homogenizing Mixing
Pressurizing
Vent
Metering
Mix Head
(2)
(2)
(6)
‰ Gentle plastification via balance of high surface area (mixing), shear heat (screws) & external heat (barrel)
throughout length of processing chamber to achieve fusion of PVC formulation, without reaction of blowing
agent until material exits extruder and enters die
‰ Removal of volatiles and entrapped gas in vent zone. This is very critical to the success of PVC foam processes!
‰ Homogenize and smooth out melt in metering zone; Pressurize material to push through die
‰ Additional gentle mixing in Mix Head to 1) disperse melt & eliminate possibility of screw marks in extrudate;
2) If a foam process, react blowing agent as it exits from extruder and enters die
Counter-Rotating Twin Screw Extruders for PVC
September 26-28, 2007 – Boston, MA
‰ Because of the shear sensitivity of PVC, twin screw extruders have
dominated the PVC extrusion field.
‰ Screw designs among the major suppliers vary greatly in design
‰ Twin screw extruders rely more on heat transfer and less on shear.
‰ Objective is to increase heat transfer early in the extruder to minimize
the need for shear input for melting
‰ Two basic theories to screw design:
9 Low surface area / High shear
9 High surface area / Low shear
‰ See graphs of energy input
High & Low Surface Area Screw Designs
September 26-28, 2007 – Boston, MA
‰ A low surface area design
requires high shear to reach
ideal melt temperature.
‰ A high surface area design
allows the material to reach a
higher temperature prior to the
compression zone, thus
requiring less shear to get the
process to ideal temperature.
High Surface
Area-Low Shear
Low Surface
Area-High Shear
Combination of Heat Transfer & Shear
The “Acceptable” Process (Melt) Temperature Range
Process Window for Low Surface Area/High Shear Design
Process Window for High Surface Area/Low Shear Design
High Surface Area / Low Shear Design
September 26-28, 2007 – Boston, MA
Pressure Drop Mixing
High Surface
Area Design
Low Surface Area / High Shear Design
September 26-28, 2007 – Boston, MA
Low Surface Area
Design
Poor Heat Transfer
Increasing Compression
Leads to High Shear
Various Ways of Measuring L/D
September 26-28, 2007 – Boston, MA
‰ Longer L/D is good – adds more Heat Transfer. Surface area
addition with screw design is preferable.
9 If the screw design is correct you only need 24-28 L/D
9 High filled formulations, clear semi-rigids, flexibles or wood
composite materials require more residence time and work
and may require longer L/D to be processed
‰ If L/D is too long, problems can occur:
9 Twist of screws causes design issues at the exit end of the
extruder
9 Wear and flex failures can be more pronounced necessitating
the use of wear resistant materials such as tungsten carbide
‰ Additional length can be obtained through the use of a pre-heater
upstream of the extruder to elevate and stabilize the temperature
of the raw material feed stream
Strength in the Gear Box !
September 26-28, 2007 – Boston, MA
Torque Master®
‰ Newer 4-shaft gear boxes have
been successful in reducing the
total torque transferred in one gear
stage to 17.5%, whereas traditional
3-shaft gear boxes are at 30% of
total torque on one gear.
‰ Allows for a 40%+ higher motor
rating, thus helping to meet today’s
higher output requirements
‰ Greater stability & reliability
‰ More output per extruder size
‰ Longer service life
Source: Eisenbeiss Torque Master Gear Box 4-Shaft and Gearing Arrangement
Summary and Conclusions
September 26-28, 2007 – Boston, MA
‰ The most important technical advances in any extruder continue to be in the
ability to reach higher output rates while maintaining melt homogeneity; in
the strength of the gear box; and in the quality of the control system.
‰ Pipe, the largest segment user of rigid PVC will continue to increase in
diameter and match PE which is already at 72”. The tooling is already
developed, and is designed to handle up to 10,000 lbs/hr. The Extruder will
need to achieve this too, meaning the technology will advance to the next
level.
‰ Extrusion lines will be going faster and faster. In the meantime, many
processors are improving their productivity by focusing on improvements to
existing equipment and tooling, upstream and downstream systems.
‰ Total cooling length is important. Proper cooling at high throughput rates is
absolutely required to maintain the best possible physical properties in all
extruded products from PVC.
‰ Power and water consumption will be key issues as costs for power
continues to increase and our sources for fresh water become more scarce
and difficult to access.
Summary and Conclusions
September 26-28, 2007 – Boston, MA
Options Available to Go Bigger & Faster:
‰ One single large extruder to
handle the full range of output
or
‰ Two extruders feeding a reverse
Y-Block and combining the
outputs of the two to make a
single product.
Summary and Conclusions
September 26-28, 2007 – Boston, MA
Alternatives available for continuing to grow:
Maintaining L/D in the 24-26:1 range and incorporating a Pre-Heater
OR
Extending the L/D and having the extruder handle the full range of output alone