COMPRESSION MOLDING

Least complex of thermal set molding processes Wide variety of size, shape and complexity of parts available Preform is placed directly in cavity Rubber is compressed, under heat, between top and bottom plates Compound flows to fill cavities, spilling into overflow grooves When cure cycle is complete, plates open, and formed parts are removed Typically, deflashing or trimming is required as a secondary operation Typically requires the least expensive tooling. Typically works best for all-rubber parts (no inserts)

 

 

TRANSFER MOLDING

Most versatile molding method Uncured rubber is placed in transfer pot Under heat, ram pushes fluid rubber into cavities Under continued heat and pressure, rubber vulcanizes to cavity shape When cure cycle is complete, parts are removed; “transfer pad” must also be removed Secondary operations may be required; flashless/trimless available Tooling costs vary based on design complexity Designed for complex part geometry Allows for over-molding of inserts

 

 

INJECTION MOLDING

Most automated process Uncured rubber is injected into cavities via a runner system and gates into closed mold Under continued heat and pressure, rubber vulcanizes to cavity shape When cure cycle is complete, parts are removed; runner system must also be removed Secondary operations may be required; flashless/trimless available Tooling costs typically higher than for other processes Designed for high volume/ high speed Allows for over-molding of inserts