English

Right Weight Packaging – Caliper and
ECT are not what they used to be!
Randy Banks
Sharp Intl / Korutest Limited
MD Torsional Stiffness Testing
Chalmers DST
An easy and accurate way
to measure MD Torsional Stiffness
using a natural resonance
technique
BPI Calculator for the Chalmers DST
USA version for C flute
Medium Type
RF
Type in component
weights - lbs
Single Facer Liner
35
Medium
23
Double Backer Liner
35
Model BPI result
11.0
Click on cell and use drop down arrow to select Medium Type
Chalmers DST Sample Template
Why is MDTS important?
MD Torsional Stiffness (MDTS) is the most basic rigidity
property of corrugated board – it is the rigidity of the core, a
basic engineering property.
MDTS failure leads to bending stiffness failure
Bending stiffness failure leads to box panel bulge
Box panel bulge leads to board compression failure
Board compression failure leads to box collapse
MDTS is the property that tells you how well you make your
board on the corrugator then how well you treat it during
box manufacture
MDTS is the property that allows you to set your corrugator
and converting machinery to maximize the paper properties
Building in Torsional Stiffness
Corrugator influences
•Selection of liners and mediums – type, quality and basis weight
•Corrugating temperature, moisture, friction, drag
•Corrugating rolls – profile, size, wear
•Glue application – film thickness, evenness, quality
•Adhesion – pressure roll, tack development, temperature
•Pressure rolls during drying
•Slitting
•Feed rolls anywhere
Sources of Crush on the Corrugator
Where do we start?
We need to start at the very end of the corrugator by
sampling board at the chop (shear) knife and near the down
stacker.
Conventional Knife Pull / Exit Roll Crush
Double Facer Crush
Traction Section Crush
Spiral Corrugator Belt
Spiral Corrugator Belt
Advantages
Very High Permeability allowing heat and moisture to escape.
Combined board exits the DB flat, perfectly bonded (not too dry) ready to convert immediately
Marked improvement in board quality: increased caliper and improved mechanical values
No delamination at the cut off knife
Less glue and less washboarding
No Seam marks
Sprialbelt is self cleaning with uniform thickness throughout the entire life
Steam Exiting Spiral Corrugator Belt
Single Facer Variables
Roll pressures in this
section are crucial for
good performance.
Up to 20% increase in
DST has been
obtained by simply
adjusting the
corrugator or pressure
roll pressures.
Caliper and ECT will
probably not change.
Corrugating Roll Profiles
Corrugator Labyrinth – the convertors input
How do we know the Best Run
Settings for each board grade?
Corrugator Process Control
Corrugator Process Control
Dry End
Ø Order entry for one, two or three knives
Ø Order change initiation – All order changes will be initiated by the control system
Ø Downtime tracking – Determine and report Corrugator downtime
Ø Automatic order download and alignment to the Dry End Controller – The control system will download production information to the Dry
End Controller
Ø Interfaces to office system for automatic order downloads and production feedback reporting – The control system will receive order data
from the office system and return production and downtime information
Ø Overhead display interfaces – Software interfaces to existing overhead display boards
Ø Intelligent Corrugator speed control – Maximize production speeds by controlling in relation to order specifics and wet end paper
requirements
Ø Load label printing – Print load labels for each load leaving the Corrugator
Ø Virtual overhead displays – Large screen TV/PC display interfaces
Corrugator Process Control
Wet End
Ø Bridge Contents Control – Maintain bridge contents at an optimum level
Ø Bridge Contents Validation – Determine exact bridge contents for accurate synchronized splicing
Ø Bridge Break Detection – Detect web breaks on the bridge and stop the Corrugator
Ø Roll Stand Monitoring – Calculate roll data such as length remaining, diameter, paper caliper…
Ø Butt Roll Indication – Highlight small butt rolls that will be left based on current production information
Ø End of Roll Splicing – Automatically splice out when a roll reaches a core before the paper tears
Ø Paper Break Detection – Detect paper breaks at the splicers and stop the Corrugator
Ø Split Roll – Feature to allow rolls to be spliced at set diameters to avoid leaving butt tolls
Ø Synchronized Splicing – Control the splicing sequence at a Wet End order change to remove all of the splices with minimal waste at the
rotary shear
Ø Waste Tracking – Track waste from the double backer entry for automatic removal at the rotary shear. Push button activated
Ø Wrap Arm Monitoring – Calculate the current wrap position to determine paper paths around the pre heaters for accurate synchronized
splicing
Ø Splice Tracking – Track splices to the knife/stacker and highlight
Ø Roll stand lowering – Automatically lower the roll stands prior to end of roll splicing
Ø Roll stock interface– Provide Roll Stock System with roll consumption data to maintain accurate stock levels and provide traceability of paper to Dry End
orders
Ø Butt roll label printing – Automatically print roll labels with accurate dimensions following removal from the Corrugator
Ø Automatic dry spot removal – automatically track and remove bridge waste at the rotary shear after long stop durations
Corrugator Process Control
Closed Loop
Ø Laser Bar – Monitor warp at the Dry End. Feedback from the Laser Bar is used within the system to control the warp via board grade
Ø Double Backer Hoods/Shoes – Control the hood/shoe combinations by speed and temperature for each board grade
Ø Double Backer Steam Pressure Valves – Control the steam pressure in each zone for each board grade
Ø Glue Unit Gaps – Control the glue gaps at the glue unit by speed for each board grade
Ø Wrap Arms – Control the wrap arm position by speed and temperature for each board grade
Ø Single Facer Glue Gaps – Control the gaps at the single facer by speed for each board grade
Ø Single Facer Corrugating Roll Gaps – Control the gaps at the single facer by speed for each board grade
Ø Single Facer Pressure Roll Gaps – Control the gaps at the single facer by speed/paper width for each board grade
Ø Temperature Sensors – Monitor/control of paper temperatures
Ø Steam Showers – Initiate steam showers by speed for each board grade
Ø Bridge Tension – Control the bridge tension by board grade
Ø Splicer Tension – Control the splicer tension by paper type
Ø Pre Heater/Pre Conditioner Steam Pressure Valves – Control the steam pressure in the pre heater for each board grade
Ø Single Facer Steam Pressure Valves – Control the steam pressure in the corrugating and pressure rolls for each board grade
Ø Vessel Temperature Monitoring – Monitor and display steam vessel temperatures
Ø Single Facer Roll Loading Pressures – Control the loading pressures in the Single Facer by board grade
Ø Boiler Monitoring – Monitor and display boiler data and functions
Ø Boiler Output – Control the boiler output by board grade
Ø Starch Kitchen Monitoring/Control –Monitor and display starch kitchen data. Control addition of resins and other additives
Board properties vs crush
C Flute Crush vs DST and Caliper
100
90
Caliper
2
R = 0.9627
80
Vaule (%)
70
60
50
DST
40
30
20
2
R = 0.9903
10
0
0
5
10
15
Crush (% )
20
25
30
Effect of crush
Cyclic humidity compression creep
Cyclic Humidity Compression Creep
DST Sample
Impact of Crush on Corrugated
 Reduces Caliper
 Softens Board
 Reduces ECT
 Affects Flexural Stiffness (FSI)
 Reduces Stacking Strength
Impact of Crush on Corrugated
 Reduces Caliper
 Softens Board
 Reduces ECT
 Affects Flexural Stiffness (FSI)
 Reduces Stacking Strength
SIGNIFICANTLY REDUCES DST
MDTS and stacking performance
Right Weighting: Cost Savings Model
Actual = tested DST
lbs to gsm x =
Medium
ALTER board grades & prices Use
RF
SC
4.882
Offset
-5.057
-5.057
-2.057
USA Board Grade - C Flute
Cost/1000ft²
DB
Medium
SF
Old Board $
27.44 Now
35
23
35
New Board $
25.20 New
31
23
31
Cost Savings $
Cost % savings
Weight savings (lbs)
Wgt % savings
2.24
8%
8
8%
Actual Theory DST
9
11.0
10.0
Payback for the Elimination of Crush
MD Torsional Stiffness is:

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

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The missing major strength property of corrugated board
The property that tells you how well you make your board
The property that tells you how badly you crushed your board
The property that tells you how well your board will perform in the
service environment
The property that leads to box failures in a stack
The major property you need for Quality Control
The property that allows you to optimize board grade
performance