Extruder machine troubleshooting for engineers.pptx

a clear explanation to solve common problems in a pipe manufacturing industry

1. PIPE EXTRUSION TROUBLESHOOTING Prepared BY: ANAOL ASHINE QUALITY Coordinator

2. In this training we will focus on PE pipes extrusion machine problems & troubleshooting. So after this training you will understand how to solve and troubleshooting PE extruder Machine.

3. Before dealing with specific extrusion problems, there are some issues that should be addressed first. There are some important prerequisites to an efficient problem solving process. these are: Good instrumentation with data acquisition system (DAS) Good understanding of the extrusion process Collect and analyze historical data information Practice critical and independent thinking Document the troubleshooting process and develop a database Team building IMPORTANT REQUIREMENTS

4. Good Instrumentation The extrusion process is to a large extent a black box process. In other words, it is not possible to visually observe what goes on inside the extruder. We can see material going into the extruder and material coming out of the extrusion die. However, what happens between the feed opening and the die exit cannot be seen on normal extruders because the process is obscured by the extruder barrel.

5. CORPORATE TRAINING AND PLANNING EXTRUSION Continuous Process In principle, the plastic raw material is plasticized by means of a screw plasticization unit and the molten material is continuously pumped out through a standard orifice (die) in order to take the shape and then the shape is set by cooling/sizing system. Example:Film,Pipe,Tube, Profile, Monofilament, Box Strapping etc.

6. MAIN TYPES OF PROBLEMS The number of extrusion problems that can occur is nearly infinite. In this training we will discuss on the following problems. Output problems Appearance problems Functional product properties High melt temperature High motor load Wear of screw and/or barrel

7. These problems can be tensile strength, cracking, etc. basically, any undesirable property that makes the product unable to perform its intended function. It may be hard to list all the cases that Can make a part nonfunctional. This can be related to mechanical properties, electrical Properties , optical properties, etc. An example of a functional product problem is environmental stress-cracking, ESC. In this problem fracture occurs when the plastic product is under stress and exposed to a chemical that reduces the Crack resistance of the plastic. For instance, detergent can cause ESC in HDPE Functional product problems

8. Problem causes solutions Die (extrudate) lines. -Damage to the exit edges of the tip or die. -Die drool or build-up on the tip or die faces. - Refinish tip or die exit edges to sharp and uniform about the diameters. -Adjust temperature of the die exit accordingly Extruder output is less than it should 1- Extruder drive belts slipping 2- Feed throat blocked “chocking” 3- Screw blocked 4- Screw starve fed 5- Die/Extruder temperature too low 6- Screen pack blocked 7- Worn or wrong screw or die design 8- Variation in bulk density / MFR 1- Tighten belts or change if worn 2- Increase water cooling for feed throat / Make sure in/out piping not blocked with scale. 3- Clean / purge extruder 4- Increase feeding rate 5- Increase set temperatures 6- Change screens / check for contamination 7- Check or change screw / change die design 8- Check bulk density / MFR

9. Actual Temperature overrides set temperature 1- Extruder zones set temp. too low 2- Improper screw design 3- Worn screw 4- Busted sensors / controllers 5- Malfunction of heating bands 6- Malfunction of cooling fans 7- High screw RPM 1- Raise set temperature 2- Change screw 3- Change screw 4- Check and replace if busted 5- Check heating bands, replace if busted 6- Check cooling fans, replace if busted 7- Check RPM / screw configuration Extruder Surging (High Output Variation) 1- Extruder drive varying speed 2- Extruder / die temp. fluctuation 3- Worn screw and/or barrel 4- Poor die design 5- Rough die/mandrel surface 6- Feeding zone temperature too high 7- Feeding throat cooling rate too low 8- Unmelted resin in metering zone 9- Varying feeding rate 10- Slippage in haul-off 11- Insufficient back pressure 12- Inconsistent pellets geometry / size 1- Check drive control / power / motor capacity 2- Check temp. controllers & cooling fans 3- Check and replace if worn 4- Change die design 5- Streamline / chrome die set 6- Lower feeding zone set point 7- Increase water flow rate 8- Increase temperature in transition/metering zones 9- Stabilize the feeding rate 10- Check haul-off drives, belts in good shape 11- Use finer screen mesh / lower temp in adaptor 12- Check pellets geometry / size.

10. High Melt Pressure 1- Melt temperature too low 2- High melt friction in barrel/die 3- Improper die design 4- Very high RPM 5- Very fine screen mesh 6- Eccentric die/mandrel setting 7- Low MFR 1- Increase temperature in extruder last z 2- Check design of screw & die 3- Change die design one/adaptor 4- Lower RPM 5- Use wider-opening screen mesh 6- Center die/mandrel set 7- Check MFR Die Drool 1- Damaged die or mandrel exit edge 2- Degraded resin accumulation 3- Inhomogeneous extrudate 4- Improper drying 1- Inspect and repair damage 2- Find and fix areas of flow channel melt degradation 3- Refer to inhomogeneous extrudate problem 4- Pre-dry resin to bring moisture to acceptable level Die Swell 1- Short die land length 2- Abrupt flow channel before die land 3- Low melt temperature 1- Optimize die land length 2- Reconfigure flow channel to streamline form 3- Increase temperature in die head zones

11. Inhomogeneous extrudate 1- Poor screw design 2- High molecular weight resin temperature 1- Check screw design 2.1- Increase melt 2.2- Increase screen mesh pack for filtration Wavy Internal surface 1- Too low melt temperature 2- Unstable haul off speed 3- High moisture content 4- Extruder Surge 1- Increase temperature in last 2 zones of extruder, adaptor & die zones 2- Check pressure is correct & belts are in shape 3- Pre-dry resin to bring moisture to acceptable level 4- Refer to surge problem above Variation in pipe diameter 1- Incorrect size of calibrating sleeve 2- Fluctuation in vacuum 3- Rubber seal rupture 1- Check sleeve for correct size 2- Check vacuum pump 3- Check seal and replace if ruptured

12. Variation in pipe wall thickness 1- Extruder surge 2- Slippage in haul off 1- Refer to surge problem above 2- Check haul-off drives, belts in good shape Rough Internal Surface 1- High moisture content 2- High inhomogeneous pellets in resin 1- Pre-dry resin to bring moisture to acceptable level 2- Refer to inhomogeneous extrudate problem Dull External Surface 1- Too low melt temperature 2- Non-uniform extrudate cooling 1- Increase temperature in last 2 zones of extruder, adaptor & die zones 2- Check uniformity of cooling after die

13. Die Lines (Straight lines in extrusion direction) 1- Die drool 2- Surface defect in die 3- Residue from screen mesh 4- Defect in calibrating sleeve 1- Refer to die drool problem above 2- Check and fix die surface 3- Dismantle and clean die 4- Inspect and fix sleeve Marks on external surface 1- Pipe sticks on sleeve 2- Misalignment of calibrating sleeve 3- Improper pipe supports 1- Increase cooling water flow, reduce RPM 2- Align sleeve 3- Check pipe supports Melt fracture (Short cracks in extrusion direction) 1- Exceeding critical shear rate 1.1- Streamline/chrome die head set 1.2- Increase melt temperature 1.3- Increase die land length 1.4- Reduce RPM Visible weld line 1- Discontinuity of resin in die 1.1- Increase melt temperature 1.2- Change die design 1.3- Increase die land length

14. Sharkskin Effect (cracks perpendicular to flow direction) 1- Variation in resin flow inside die 1.1- Pre-heat resin before extrusion 1.2- Increase temperature in die 1.3- Reduce melt pressure or reduce RPM 1.4- Increase die land / die gap Bubbles & Pores 1- High moisture content 2- Entrapped air in feeding section 3- Water splash before vacuum tank 1- Pre-dry resin to bring moisture to 300ppm max. 2- Increase temperature in feeding section 3- Increase vacuum Melt degradation 1- Too high melt temperature 2- Long melt residence time 3- Residues of material in extruder/die 1.1- Lower die/barrel temperature 1.2- Change screw design 1.3- Lower RPM 2.1- Reduce residence time 2.2- Check for stagnation spots is die 3- Clean screw, barrel & die head Thick pipe sagging 1- Too high melt temperature 2- Improper die/mandrel centering 3- Cooling is not enough 1- Adjust settings to reduce melt temperature 2- Adjust die gap to accommodate sagging 3- Assure availability of required cooling water

15. Problem Possible Cause Suggested Action Oval Pipe 1- Short cooling length / high output 2- High temperature of cooling water 3- Improper pipe support 4- Improper coil internal diameter 5- varying pressure of haul-off belts 1- Use more cooling baths / reduce output 2- optimize temperature of cooling water 3- Check pipe supports 4- Increase internal diameter of coiler 5- Check pressure supply to haul-off

16. Fold b/c of improper w/m setting

17. Splity or Teared pipe

18. Totally shriNked pipe

19. Trapped air defect

20. FOLD WITH DOTED WATER MARKS

21. INDENTED Water LINES & marks

22. Internal deep lines caused failure & external damage caused failure

23. Rough surface inside Can be caused by moisture or low melt temperature or dirty metal surfaces. Sticking and seizing on mandrel or sleeve surfaces can cause roughness. Very high linear extrusion speeds can cause melt fracture at the die, which is caused by higher temperature, longer die lands and smaller internal entrance angles into the die-head section. When roughness is observed, try to locate the exact point of its origin. A strip or roughness on the underside is caused by uneven water cascading; direct another cascade from bottom upward or cascade all around the pipe. Strip roughness on the outside can also be caused by misaligned sleeve or some foreign matter caught in the sleeve sizing plate. A ripples strip of roughness can be caused by a difference in wall thickness at that point. Roughness all over, especially in little V-shaped marks pointing away from the die aroused from insufficient mixing and Occasionally also from moisture in

24. Splity pipe for visible weld marks and check if failure is along weld lines. Extrusion may too cold or too fast. Raise melt temperature or improve die design by increasing long length to develop more pressure Excessive draw down can produce split pipe even with proper re-welding of split streams. Check pipe for unbalanced orientation in extrusion direction.

25. Lack of Gloss Same problems and remedies as rough surface discussed above. Raising melt temperature is Most likely a remedy. Some die cores are electrically heated to give batter internal gloss. The exterior can be flame polished if linear speed is slow. Sizing sleeves can give best outside surface. Formulation can be Improved to give better gloss, e.g. Lubricants in PVC.

26. Poor strength See `Split pipe' above. Also indented printing can weaken pipe, as can too much Draw down at Low temperature. Look carefully for nicks and grooves that could concentrate stress. Plastic may be degraded by thermal decomposition (PVC) ultraviolet light long storage in sunlight or use of too strap in the feed. Mould a plaque from the weak pipe and compare its basic physical properties with those expected from new compound. Poor mixing can cause weak pipe even if appearance is acceptable, particularly with PVC. Remedies are given above under `rough surfaces‘ strength is very much dependent upon material formulation.

27. Discolored material Decomposition of compound, usually PVC reduces temperature or uses a different formulation (more stable or less viscous) or improves streamlining of extruder and die interior.

28. Preventative Measures Operators should fully understand the extrusion process Good machinery instrumentation and maintenance records kept Current and historical processing data available Material should be stored in a clean, dry area, without being subject to extreme temperature variation.

29. bends staggered windings oval windings On this machine those problems could be observed. so according to our krussmaffie winder machine design and capacity we can solve this problems by the following methods. winder machine problems and its suggested solutions

30. Bend happens on winder

31. Bend happens on winder

32. Problems Possible causes Suggested solutions Bends -Too much Thickness deviation on smaller wall thickness pipes. -The pipe is too cold when it reaches at the winder. - wider diameter is too small from the pipe OD needed to winding. - Adjust pipe wall thickness. - Use only the proper cooling length for smaller thickness. - Adjust winder diameter according to winding diameter formula. Staggered winding -Improper winder carriage speed setting. Haul off Machine speed too fast The gap b/n winder & haul off is short. - Set a proper carriage speed according to winder speed. -set proper Haul off speed convenient with the winder. - Increase the gap b/n winder and haul-off Oval winding - Brackets are not equally adjusted. -Adjust all the bracket in equal to center distance.

33. Problems Possible causes Suggested solutions Pipe too much oval -The pipe is too hot when it reaches the winder -Too much winding tension -use additional cooling baths or decrease water temperature . -Adjust the winder winding torque and set the winder Adjuster sensor at the proper distance. Best coils

34. THANK YOU! DECEMBER/ 2019