Transfer Molding

A method of forming articles by fusing a plastic material in a chamber and then forcing essentially the whole mass into a hot mold where it solidifies.

Transfer molding is closely related to compression molding, because it is utilized on the same polymer types (thermosets and elastomers). One can also see similarities to injection molding, in the way the charge is preheated in a separate chamber and 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 the heated plastic bonds to the insert during molding.

Types of transfer molding

  • Resin Transfer Molding (RTM)
    (RTM) Molding process in which catalyzed resin is pumped into a two-sided, matched mold where fibrous reinforcement has been placed. The mold and/or resin may or may not be heated. RTM offers the ability to consolidate structural parts. Its major drawback is the high cost of the initial, two sided mold.
  • Vacuum-Assisted Resin Transfer Molding  (VARTM)
    Is a low-cost alternative to resin transfer molding (RTM). It features lower tooling costs, room temperature processing and ease of scalability.