Plasco Inc. www.plasco-corp.com (831) 464-1111 -- Clear Plastic, Processing Archive

COMMOM PROBLEMS IN PROCESSING CLEAR PLASTICS

PLASCO WISHES TO THANK THE FOLLOWING SUPPLIERS - ARCO, MOBAY, CYRO, EASTMAN, DOW, CONTINENTAL, GE & POLYSAR. THE FOLLOWING GUIDE IS A COMPOSITE OF THEIR EXPERTISE AND RECOMMENDATION.

PROBLEM TYPICAL CAUSES SOLUTIONS

silver streading, splay , bubbles moisture check dryer operation; drying conditions; use a desiccant dryer.

entrapped air raise back psi; reduce screw decompress; add or enlarge vents.

overheated resin reduce barrel temps, back psi, screw rpm; lower inj psi, rate; open gates.

contamination check dryer, hopper; purge barrel.

voids material volume increase packing, hold time, mold temp, or shot; enlarge gates.

dark specks charred resin flakes purge machine, clean tip, non-return valve; check for excessive temp.

haze, cloudiness impurities, or low process temps check contamination; increase drying, mold or melt temps.

gate blush melt fracture & stresses at gate raise melt; reduce inj speed; check sharp edges at gate; enlarge gate.

brittleness poor impact poor part design, stresses, wet resin check dryness; review design; lower regrind %, inj psi, sharp corners.

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THE PLASCO NETWORK is published by PLASCO INC. information contained in the newsletter has been taken from sources which we deem reliable. we cannot assure its accuracy. any opinions expressed reflect our judgment and are subject to change. all rights reserved. reproduction or copying in any form, requires written permission from PLASCO INC. M. LODICO -editor

PROBLEM	TYPICAL CAUSES	SOLUTIONS
silver streading, splay , bubbles	moisture	check dryer operation; drying conditions; use a desiccant dryer.
	entrapped air	raise back psi; reduce screw decompress; add or enlarge vents.
	overheated resin	reduce barrel temps, back psi, screw rpm; lower inj psi, rate; open gates.
	contamination	check dryer, hopper; purge barrel.

voids	material volume	increase packing, hold time, mold temp, or shot; enlarge gates.

dark specks	charred resin flakes	purge machine, clean tip, non-return valve; check for excessive temp.

haze, cloudiness	impurities, or low process temps	check contamination; increase drying, mold or melt temps.

gate blush	melt fracture & stresses at gate	raise melt; reduce inj speed; check sharp edges at gate; enlarge gate.

brittleness poor impact	poor part design, stresses, wet resin	check dryness; review design; lower regrind %, inj psi, sharp corners.