Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001
Barrel - the cylinder the injection screw sits in.
Cavity/Impression - The two or more hollow metal parts that contain the negative of the part.
Cold Flow - material that is too cool when injected will get a dull surface finish.
Core - a protruding (or male) mold component.
Crazing - a fine mesh of cracks.
Degating - separate parts from runners
Delamination - the surface peels off in layers
Dowels/Guidepins - used to mate mold cavities
Dwell - a delay time after filling the mold
Ejector Pins - push the part out of the mold as it is opened
Feed - the volume of plastic injected into the mold as it is advanced
Flash - a thin flat section that has "squirted" out of the mold
Gassing - trapped gas marks and burns the mold
Gates - the entry port between the runners and the parts
Granules - the pellet form that raw plastic is delivered in.
Granulation/Grinder - will reduce parts to granules for reuse
Inserts - parts placed in the mold before closure and injection. These become an embedded part of the final product
Nozzle - the plastic is ejected through the nozzle to the mold.
Polymers - The chemical category of plastics
Powder - a finely ground material
Preheating - plastic may be heated before use to remove moisture contaminants
Purging - a few purging shots are made when changing the material
Ram - opens and closes the platens
Regrind - reclaimed plastic granules
Release Agent/Spray - A spray, such as silicone, can be sprayed into tight molds to ease part removal.
Runners - connect the gate to the sprue
Safety gate - the gate must close and shut the operator out for the press to close.
Shot - one injection of plastic
Short shot - insufficient plastic is injected
Shrinkage - reduction in size as mold cools
Sinking - Surface deformation on parts.
Sprue - excess plastic between the injector nozzle and the mold
Vent - A small gap that allows air to escape as it is displaced by molten plastic
Warped - Cooling stresses cause a part to twist, or warp, to a new shape.