Reaction Injection Moulding (RIM)

RIM green mould filled with resinReaction Injection Moulding (RIM) is a process where a fast reacting PU (polyurethane) resin is injected into a mould at low pressure.

 • High Impact • High Heat Resistant • V0 Rated

This process, which fits between Vacuum Casting and Thermoplastic Injection Moulding in the prototyping / manufacturing chain, is a cold injection process that does not require pre-heating of moulds or post-curing of castings.

Larger sized components can be produced and several moulds can be moulded consecutively, leading to quicker production times.

Tools are made from Silicone, Resin, Model Board or Aluminium.  This process is mainly used for larger and simpler parts with a typical wall thickness of 2-3mm+. 

A wide range of production simulant materials are available, offering a wide range of properties; rigid or flexible; solid or foamed, with a density as low as 40 kg/m³.

Rigid self-skinning materials, where the surfaces are hard and solid enclosing a foam core, can be moulded to produce lightweight but rigid components.



Hepworth is a 1st Tier supplier to many industries, including the marine, rail and automotive sectors.

Rim moulded car part

Our Moulding Division specialises in reaction injection moulding (RIM), working to the highest levels in component moulding and finishing, through to supplying fully assembled units. Our finishing department gives fine attention to detail, ensuring that every product is completed to the highest possible quality standard.  We have:

  • A wide range of resins available
    Including rigid, semi-rigid, flexible, high impact and high temperature resistant resins.
  • The ability to produce dimensionally accurate mouldings
  • The capability to produce product sizes
    Varying from a matchbox weighing just a few grams, to a product the size of a car bumper weighing up to 15 kilos.

We are able to buy materials at very favourable rates and this is reflected in our quoted prices and we can supply tooling, however free issue tooling is welcome and we offer various finishing processes – please ask for further information.


Group Brands

Hepworth RIM Mouldings - RIM Moulding Hepworth RIM Mouldings - RIM Moulding Hepworth RIM Mouldings - RIM Moulding Hepworth RIM Mouldings - RIM Moulding Hepworth RIM Mouldings - RIM Moulding