A thermosetting charge is loaded into a chamber immediately before the mold cavity where it’s heated.
Pressure is then applied to force the softened polymer to flow the heated mold where curing occurs.
There are two variants of the process. These are
Pot transfer molding - The charge is injected from a pot through a vertical sprue channel into the cavity
Plunger transfer molding - The charge is injected by means that of a plunger from a heated well through lateral channels into the mold cavity.
In each cases scrap is produced each cycle in the form of the leftover material in the base of the well and lateral channels known as cull.
In addition the sprue in pot transfer is scrap material. As a result of a polymers are thermosetting, the scrap can’t be recovered.
Transfer molding is closely associated to compression molding as a result of it’s utilized on the same polymer types.
In the way the charge is preheated during a separate chamber then injected into the mold.
Transfer molding is capable of molding part shapes that are more intricate than compression molding but not as intricate as injection molding.
Transfer molding also lends itself to molding with inserts in which a metal or ceramic insert is placed into the cavity prior to injection and also the heated plastic bonds to the insert during molding.
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