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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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