Troubleshooting, Monofilament Extrusion

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PROBLEM	CAUSES & SOLUTION
FILAMENT BREAKAGE	A) Surging in extruder, run at high pressure or with better mixing screw of with cooled screw,or with gear pump or more slowly. Try to determine period of the surging ,and relate to drive controllers etc.
	B) One or more holes partially blocked the same filament will break ever time.
	C) Uneven temperature or distribution of material in head and die. The same group of filaments will break every time.
	D) Melt too hot not enough ductibility to draw down. Raise the temperature.
	E) Melt too hot too fluid to hold together under drawing tension. Reduce temperature.
	F) Draw down too great (use smaller holes in die) or drawdown too fast (slow down whole system).
	G) Contamination in material inspect feed stop using reground or reworked plastic.
	H) Moisture in material use a hopper dryer.
	I) Oxidation and weakening of filament furface run at lower temperature or reduce the gap between die and quech bath.
	J) Decomposition in extruder head or die bits or decomposed material clog holes or come through them but weaken the filaments. Clean die run at lower temperature examine die change die or head if necessary use better starliser plastic.
	K) Too much orientation if plastic is not hot enough too much tebsuke stress will be produced in the filaments.
	L) Too hot orientation if plastic becomes too hot it loses ductibility and will break under the normal orientation stresses.
	M) Too cold orientation if plastic is not hot enough too much tebsuke stress will be produced in the filaments.
	N) Nicks or abrasive areas on any of the rolls grind them smooth or wrap them with tape.
	O) Erratic drive check smoothness of operation of all moving parts.
ALL FILAMENTS VARYING	Surging in extruder drawdown too much or too fast or erratic drive see above.
SOME FILAMENTS DIFFERENT FROM OTHERS IN SIZE AND STRNGTH	A) Temperature gradients in die unequal follow in die check for drafts burn out heaters poor die design.
SOME FILAMENTS DIFFERENT FROM OTHERS IN SIZE AND STRNGTH	B) Take off not exactly alligned with die and extruder.
POOR SURFACE APPEARENCE	A) Moisture in material possible with polystyrene nylon or any pigmented or filled plastic. Dry the feed.
	B) Melt fracture reduce linear speed or reduce entrance angle into die holes or use lower viscosity compound or run hotter
	C) Plastic too cold run hotter.
	D) Compound inherently dull change compound or run hotter or flame polish.
LOW TENACITY	A) Not enough orientation increased ratio of roll speeds. Use proper orientation temperature not that changes of orientation may also change the filament size, requiring compensating adjustments elsewhere.
	B) Degraded plastic use lower material temperature or change to better stabilized formula.
	C) Plastic unsuitable for filaments check with its manufacturers.
	D) Nicks or cuts in filaments examine breaks and examine unbroken filaments look for a repetitive pattern and examine take-off for the source.
HEAVY FILAMENTS DO NOT LIE STRAIGHTS	Filaments would around a roll while still warm. Adjust filament or roll cooling.
OVAL CROSS SECTION	A) Filaments too hot while passing over rolls especially in quenching bath. The rolls themselves could be too hot.
	B) Die holes not truly found.
	C) Temperature gradients in die effect roundness. Most likely in T-type die with all holes in a line.
	D) Too much tension in wrapping around any rolls.