IMM 1/01

Has anyone performed a test on the consistency of a product molded with and without gate freeze-off?

Invariably, if hold time ends before the ate freezes off, there is going to be part weight variation, due either to molten material backflowing out of the cavity or lost "packing opportunity" (i.e., the cavity won't be packed all the way). The variation may not show up by itself. It may be initiated by variation or change in another part of the process; for instance regrind percentage or material lot change. The best thing to do is establish gate freeze during process development, thus optimizing hold time and eliminating that as a potential source of variation. - B. Tutmark, GM Nameplate Oregon Div., Beaverton, OR (503) 646-0444, bradt@gmnameplate.com.