| Problem |
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Possible Cause |
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Possible Solution |
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| Excessive motor amperage |
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Early fusion |
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Reduce rear barrel temperature to avoid early fusion |
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Reduce oil temperature of screw |
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Use a slower fusion compound |
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Excessive back pressure |
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Increase die temperature to decrease back pressure |
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Increase orifice size in adapter to reduce restriction on screws |
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Lower output to decrease throughput |
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Increase barrel and screw temperature to increase melt temperature |
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Increase die temperature to decrease pressure in die |
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Increase orifice size |
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Use a more externally lubricated compound |
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Excessive feeding |
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Decrease feeder speed to reduce material in feed throat |
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| Orange peel |
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Melt temperature too cold |
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Increase temperatures on barrel and screw |
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Lube imbalance or contamination |
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Purge extruder again as purging itself could be the source |
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Line speed exceeds tooling |
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reduce line speed |
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| Melt rough on sides only |
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Increase screw oil temperature |
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| Lumps (small) |
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Insufficient fusing at vent |
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Increase rear barrel temperature |
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Increase screw oil temperature |
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Insufficient mixing in metering zone |
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Decrease orifice size |
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| Rough edges |
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Increase die temperature |
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Increase melt temperature |
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Check die for blockage |
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| Grainy surface |
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Insufficient vent |
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Increase vacuum |
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Cooling water temperature for vacuum pump to high |
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Check water, vent, pump and filters for proper operation |
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Melt temperature too high |
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Reduce barrel and Screw temperature |
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Volatiles are sealed in at vent |
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Reduce rear barrel temperatures |
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Line is running too high |
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Reduce speed or adapt tooling and formulation |
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| Swirls |
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Delayed fusion |
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Increase rear barrel temperature |
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Increase screw oil temperature |
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Insufficient pressure at screw tips |
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Decrease orifice size in adapter |
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| Blisters |
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Material wet |
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Dry it by pre-heating |
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Increase vacuum |
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Severe pressure drop at tooling |
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Change orifices |
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| Heat Sinks |
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Melt temperature too cold |
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Increase extruder temperatures |
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Die is too cold (small heat sinks) |
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Increase die temperature |
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First calibrator too cold |
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Increase temperature / decrease water flow |
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Insufficient vacuum |
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Increase vacuum carefully |
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| Dimples (in a straight line) |
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Water is leaking onto profile in first calibrator |
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check first calibrator |
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| Dimples (at random) |
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Air bubbles forming on profile in water tank between first and second calibrator |
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Increase water velocity / temperature |
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| Low gloss |
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Melt temperature too low |
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Increase barrel and/or die temperature |
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Water contact with profile too early |
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Delay water contact |
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First calibrator too cold |
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Increase calibrator temperature |
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Decrease water cooling by decreasing water flow to calibrator |
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| Scratches/Drag Lines |
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Calibrators too new |
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Keep on using |
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Vacuum too high |
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Decrease vacuum (without affecting sizing) |
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First calibrator too cold |
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Increase calibrator temperature |
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Water temperature too low |
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Increase water temperature |
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| Poor impact |
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Melt temperature too low |
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Increase barrel temperature |
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High moisture content of material |
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Check material in hopper |
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Check venting to be sure volatiles are all removed |
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Increase rear barrel temperature |
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Material over fused at vent and sealing in volatiles |
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Decrease rear barrel temperature |
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| Profile bowing (to the left) |
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Die out of balance |
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correct die geometry |
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Uneven cooling |
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Add more cooling to the left side or reduce cooling on right side |
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Too much make up water entering tank from right side |
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| Chatter |
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Calibrator misalignment in tank |
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adjust calibrator |
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Vacuum too high (therefore to much drag in calibrator) |
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Decrease vacuum |
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Puller |
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Air pressure/clamp force too low,slipping |
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Puller drive not stable |
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Profile over size, pinching in calibrator |
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Cooling water too cold, profile shrinking too fast |
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Increase water temperature |
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Water making contact to early |
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Delay water making contact after skin is set in first calibrator |
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First calibrator too cold |
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Increase temperature |
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Profile is too tight in seal on end of tank |
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| Sudden loss of die balance |
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Die temperature too high |
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Check thermocouples, controllers |
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Check extruder barrel temperatures |
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Check all extruder barrel heater bands |
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Check die heater band for even heat |
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Flank Play |
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Check flank play on extruder screws |
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Blockage in die |
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Clean die |
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| Plate-out in calibrators |
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(there are many theories) |
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Increase fusion of material as much as possible on rear of screws, but do not over fuse |
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Increase melt temperature to 200 C - 205 C |
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Increase temperature of first calibrator. Over chilled calibrator increases plate-ou |
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Most plate-out occurs in first calibrator and is transferred to other calibrators with the profile |
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