Extrusion troubleshooting

Barex ® Resins Extrusion Troubleshooting Guide

1. Overloading of Extruder Probable Causes A. Extruder Motor torque too low at operating RPM torque at low RPM

Suggested Course of Action 1.

B. Compression ratio of screw too high 1. causing feed to overdrive metering section.

Increase gear ratio to give more torque at low RPM

2.

Decrease screw compression to approach volume compression Starve feed screw

C. Mixing sections too severe causing excessive shear work

1. 2.

Remove or reduce shear of mixing devices Increase operating temperatures

D. Operating temperature too low causing excessive work to pump high viscosity material

1.

Increase operating temperatures

2. Surging Probable Causes A. Bridging in feed section

Suggested Course of Action 1. Decrease hopper drier temperatures 2. Positively feed regrind, check blending equipment and ratio

B. Poor solids solids conveying in feed sections due 1. Make sure throat cooling in on to melting of resin in feed section 2. Lower feed zone temperature 3. Reduce temperature of screw C. High compression ratio of screw generates 1. Reduce compression ratio or starve feed heat which intermittently melts resin to reduce solids conveying and then builds pressure to overdrive metering section D. Low compression ratio

1. Increase back pressure 2. Reduce the amount of regrind 3. Increase screw compression ratio

E. Moisture

1. Dry resin before use 2. Allow longer drying times on hot humid days

F. Extruder Malfunctions

1. Reduce screw speed 2. Check for voltage variations 3. Check drive unit for malfunctions; correct slippage of motor belts 4. Check thermocouples for calibration, shorts or disconnections

G. Air Entrapment

1. Reduce screw speed 2. Lower drying temperature 3. Increase screw compression ratio and/or transition length 4. Reduce feed zone temperature

3. Poor Color of Product Probable Causes

Suggested Course of Action

A. Excessive Work Work on resin leading to high material temperatures

1. 2. 3. 4. 5.

B. Back pressure too high

1. Increase diameter of adapter 2. Install a more streamlined die

C. Feed material too yellow

1. Lower drier temperature 2. Reduce regrind level

D. Residence time too long

1. Increase RPM 2. Use smaller extruder

E. Extruder Malfunction

1. Check thermocouples for malfunctions/overrides 2. Reduce drying temperatures

4. Build-up of Brown on Die Lips Probable Causes A. Excessive melt temperatures

B. Operating die zones too high

5. Air Entrapment Probable Causes

Reduce viscosity by increasing temperature Reduce shear by decreasing RPM Reduce shear by increasing channel depths Reduce temperature settings to remove shear heat Resin freezing on screw increase screw cooling temperature

Suggested Course of Action 1. Reduce back pressure by increasing diameter of adapter to die or die clearances 2. Reduce melt temperature by reducing compression ratio 3. Reduce shear by reducing RPM increasing metering channel depth 1. Check for thermocouple malfunctions


A. Early melting of resin

1. Decrease feed zone temperature 2. Reduce feed zone length 3. Check for bridging in hopper

B. Resin conveys to metering section before completely melted thus trapping air

1. Increase compression ratio to squeeze out air 2. Increase feed zone and transition zone temperatures thus eliminating trapping the air 3. Reduce RPM 4. Increase transition section length 5. Reduce amount of regrind

6. Gauge Control (Transverse) Probable Causes


A. Die flow erratic due to uneven or faulty die heaters

1. 2.

Repair heaters Adjust die zone temperature for even flow

B. Die flow uneven due to uneven melt temperature from extruder

1. 2.

Reduce back pressure in extruder Decrease screw cooling temperature if center of web has high flow - increase if low Improve screw design to lower shear, lower compression ratio to reduce melt temperatures Reduce RPM

3. 4. C. Die design faulty

1. Die lips warped, replace 2. Improve die coat hanger design 3. Reduce back pressure

D. Improper die adjustment

1.

E. Insufficient polishing roll pressure

1. Polishing roll air cylinder pressure must be adequate to polish full width of sheet 2. Polishing rolls improperly adjusted

F. Excessive bead buildup

1. Adjust polishing roll speed 2. Check air pressure to cylinders 3. Check gap between polish rolls

7. Gauge Control (Machine Direction) Probable Causes

Readjust die lip gradually


A. Surging of material in extruder due to feed 1. conveying 2. NOTE: (amperage swings to confirm) 3. 4. 5. 6.

Reduce feed zone temperature to improve conveyin Decrease compression ratio to improve cooling capability Check feed system for bridging in hopper Screw temperature too high in feed zone Reduce RPM Reduce the amount of regrind

B. Pump ratio or second stage metering section not properly designed

1. 2.

Increase back pressure with screen packs Decrease pump ratio

C. Equipment faulty

1. Check haul off unit drive 2. Check extruder drive belts 3. Check for swing controllers

D. Moisture-air entrapment

1. Dry resin 2. Reduce screw speed

E. Polishing rolls

1. Check for eccentricity (repeating on roll) 2. Check polishing roll pressures 3. Check for excess bead in nip

F. Improper screw design

1. Redesign screw 2. Increase back pressure 3. Increase screen pack

8. Discoloration or Lumps Probable Causes


A. Contamination

1. 2. 3. 4. 5.

B. Unmelted resin

1. Increase extruder temperatures to obtain melt temperatures of 400-4200F 400- 4200F (204-215°C) (204-215°C) 2. Increase back pressure by use of breaker plate or screen pack 3. Increase compression ratio of screw

C. High melt temperature

1. Reduce stock temperature to prevent thermal breakdown 2. Reduce back pressures 3. Check for thermocouple malfunctions

D. Equipment contamination

1.

9. Dull or Rough Surface Probable Causes

Check regrind operation Check oil in air supply Check for broken desiccant bags Check loader and loader tubes Use smaller mesh screen pack

Check for contamination on screw screens, die adapter, die lips, etc.


A. Melt temperature too low

1. Increase die temperatures 2. Increase extruder temperatures

B. Hang up inside die or head

1.

Clean die and/or head surface

C. Purge material is hung on die or head surface

1.

Use higher viscosity purge material (fractional melt flow HDPE) ® Start up on Barex 210 Resin

2. D. Die surfaces do not have sufficiently smooth 1. surfaces

Buff tool to mirror finish

E. Improper chrome roll temperature

1.

In general, increase temperatures to improve gloss

F. Improper chrome roll pressures

1. 2. 3. 4.

Check air cylinder pressures Adjust speed to eliminate bead Check for eccentricity Check for damaged or dirty rolls

G. Improper die design

1.

Reduce output to compensate for short lip land

H. Large die lip opening

1.

I.

Hot spots/sticking

1. Check for scale buildup inside of chrome roll (use acid flush) 2. Use treated water

J.

Moisture

1. Increase drying time 2. Reduce the amount or regrind

K

Contamination

1. Check regrind for contamination 2. Check grinders, conveying tubes 3. Check machinery contamination (die, screw, etc.)

10. Chill Marks Marks or “Marks-Off” “Marks-Off” Lines Lines Probable Causes

Reset die lips


A. Polishing roll

1. Insufficient pressure (check air cylinders) 2. Improperly adjusted 3. Excessive bead

B. Contamination

1.

C. Die damage

1. Check for nicks, pits, scratches, dirty die lips 2. Thermocouple malfunctions

D. Blocked die

1. Check for hangup areas, degradation 2. Remove dams

11. Lines (Transverse) Probable Causes

Contamination from machinery, etc.


A. Polishing roll

1. 2. 3. 4. 5.

B. Pull rolls

1. Improper sheet tension 2. Check for worn rolls, gears, or sprockets 3. Eliminate backlash in drive train

12. Curling: Warping Probable Causes

Reduce chrome roll temperature Reduce stock temperature Increase polishing roll pressure Check for polishing roll eccentricity Check for dirty or damaged rolls


A. Polishing roll

1. Improper chrome roll temperatures (increase) 2. Check for scale in chrome rolls 3. Check for hot spots on rolls (repeats)

B. High melt temperature

1. Reduce back pressure 2. Reduce compression ratio 3. Lower controller temperatures

C. Die design

1.

Adjust die lips for less draw down

13. Orientation Probable Causes


A. Polishing rolls

1. Increase chrome roll temperature 2. Reduce excessive bead

B. Die lip-roll nip distance

1. Decrease this distance as much as possible 2. Check parallelism of rolls

C. Low stock temperature

1. Increase extruder temperature 2. Increase die temperature

D. Die design

1.

Excessive flow in certain areas of die; adjust heats

Regulatory Information The product and uses described herein may require global product registrations and notifications for chemical inventory listings, or for use in food contact or medical devices. For further information, send an e-mail to: [email protected]. Health and Safety Information The product described herein may require precautions in handling and use because of toxicity, flammability, or other consideration. The available product health and safety information for this material is contained in the Material Safety Data Sheet (MSDS) that may be obtained by calling 1-302-838-3278, or by sending an e-mail to: [email protected]. Before using any material, a customer is advised to consult the MSDS for the product under consideration for use. The Material Safety Data Sheet for this product contains shipping descriptions and should be consulted, before transportation, as a reference in determining the proper shipping description. If the material shipped by INEOS is altered or modified, different shipping descriptions may apply and the MSDS of the original material should not be used. For additional information, samples, pricing and availability, please contact:

INEOS Barex PO. Box 537 1389 School House Road Delaware City, DE 19706-0537 USA Customer Service: +(1) 302-838-3278 Fax: +(1) 302-838-3222 email: [email protected] www.ineosbarex.com

For Sales in Europe Velox GmbH Brandstwiete 1 D-20457 Hamburg Germany Tel: +(49) (0) 40 36 96 88-0 Fax: +(49) (0) 40 36 96 88 88 email: [email protected] www.velox.com

Technical information contained herein is furnished without charge or obligation, and is given and accepted at recipient's sole risk. Because conditions of use may vary and are beyond our control, INEOS makes no representation about, and is not responsible or liable for the accuracy or reliability of data, nor for toxicological effects or Industrial Hygiene requirements associated with particular uses of any product described herein. Nothing contained in this document shall be considered a recommendation for any use that may infringe patent rights, or an endorsement of any particular material, equipment, service, or other item not supplied by INEOS. The “Properties” and “Applications” listed in this document are not specifications. They are provided as information only and in no way modify, amend, enlarge, or create any specification or warranty, and ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE EXCLUDED.

The name Barex is a trademark of INEOS USA LLC. June 2006

© 2006 INEOS USA LLC

A division of INEOS USA LLC

Extrusion troubleshooting

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