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.

News Article: MFG Texas Restructures with Focus on Low Pressure Molding Processes



Resource Typesort descending Description
Mass Reduction With Value-Engineered Composites PDF Guidance for light-weighting (mass reduction) of products using advanced composite materials.
Technical Design Guide for FRP Composite Products and Parts PDF Fiberglass (FRP) composite materials and processes are explained in detail. This design guide outlines various selection criteria with helpful technical data and comparisons to alternative materials.
Guide for Selecting Best FRP Composite Process PDF Guidelines for Selecting the Best FRP Composite Process for Your Project

Snapshot Guide: Shapes, Uses and Considerations

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