Snapshot Guide: Shapes, Uses and Considerations

Low to medium volume, 2-sided finish – both good quality, in-mold coating.

Resin Transfer Molding (RTM)

Resin Transfer Molding (RTM) Process

Resin Transfer Molding (RTM) Process IllustrationRTM is a vacuum-assisted, resin transfer process with a flexible solid counter tool for the B-side surface compression. This process yields increased laminate compression, a high glass-to-resin ratio, and outstanding strength-to-weight characteristics. RTM parts have two finished surfaces.

Reinforcement mat or woven roving is placed in the mold, which is then closed and clamped. Catalyzed, low-viscosity resin is pumped in under pressure, displacing the air and venting it at the edges, until the mold is filled. Molds for this low-pressure system are usually made from composite or nickel shell-faced composite construction.

Suitable for medium volume production of larger components, resin transfer molding is usually considered an intermediate process between the relatively slow spray-up with lower tooling costs and the faster compression molding methods with higher tooling costs.

  • Recommended for products with high strength-to-weight requirements
  • Best suited for mid-volume production rates, in the range of 200 to 10,000 parts per year*
  • Gel coats may be used to provide a high-quality, durable finish
  • Tooling can be made from many different materials - polyester, nickel shell, aluminum or even mild steel. The volume and life of program and tooling budget will help determine what is best

* Volume recommendations are averages and provided only as a general guideline.  Actual volume efficiencies are a more complex matter requiring detailed statistics about the part to be manufactured.