IMM 5/99

Does anyone have a remedy for eliminating the stringing/angel hair from the nozzle tip when molding Delrin? The parts we supply go through an automated assembly machine, and angel hair jams the track, making for an unhappy customer.

The use of a valve gate will provide the gate shutoff to eliminate angel hair. A hydraulic system would require nearly a complete new mold half while a resin pressure system may fit the existing mold
-B. Smith, Fisa Corp., Shelhvville, TN, (931)684-9757.

Put a piece of .003 to .005-inch brass shim stock between the nozzle tip and the sprue bushing (with a hole in it). This should stop any stringing from the nozzle.
-B. Kuehn, GW Plastics Inc., Bethel, VT, (802) 234-9941.

With respect to Delrin, the occurrence of nozzle drool and stringing from the nozzle tip may be most easily prevented by increasing the decompression time by .2 to .6 seconds on your molding machine. If this proves to be insufficient, proceed by lowering the temperature of the nozzle itself in increments of 5 to 10 deg F. If you happen to be running this material in a hot runner tool, ensure that your gate diameter(s) does not exceed .06 inch. This will aid in minimizing the size of the vestige in the gate area and improve degating. Should you have any questions and/or comments, please don't hesitate to give me a call.
-W. Maruszczak, Dow Automotive, Midland, MI, (248) 351-5534.