Molding
An immediate chemical reaction occurs inside the mixing head, with a continued exothermic
reaction inside the mold cavity as the curing process progresses. When processing
foams, significant forces created inside the mold must be resisted to ensure the integrity
of the part. The clamping pressure required can be up to many tons depending on the
size, expansion rates, and the desired density of the part, along with other material factors.
Mounting the mold in a pneumatic or hydraulic press provides the force required to keep
the mold tightly closed during the curing process. Elastomeric materials often require very
little clamping pressure as they do not expand or generate internal mold forces.