MPM’s refined RTM process helps customers achieve consistent, high-quality GRP parts—faster and with fewer errors. By simplifying tooling from CAD to final mould, we make Resin Transfer Moulding more accessible, repeatable, and cost-effective.
At MPM, we take the headache out of GRP manufacturing, ensuring customers get the quality and quantity they want through the most effective process for the job. RTM is but one of MPM’s production processes for GRP/composite manufacturing. We continue to make strides in making RTM more accessible, consistent, and customer-friendly thanks to a proven process that takes your part from CAD to finished tool with confidence.
RTM and LRTM: What’s the difference?
RTM involves injecting resin into a closed mould cavity, typically under pressure, between a solid base and rigid top mould. It's ideal for producing high-quality, repeatable composite parts with an excellent surface finish on both sides.
Light RTM (LRTM) is a variation that utilises a lighter, semi-rigid counter mould, often vacuum-assisted, which offers lower tooling costs and simpler handling. This format is particularly suitable for medium to lower-volume runs.
Resin Transfer Moulding (RTM) is a powerful and proven process for producing high-quality, consistent composite parts. However, for many customers, transitioning from a CAD model to a fully functional RTM tool can feel uncertain and overly complex.
By applying our templated process to both RTM and LRTM, we help customers choose the best method for their part and volume requirements. And by working closely from the start, we ensure parts are delivered right first time, on time, and often ahead of expectations.
That’s why our team at MPM has developed a robust, templated process that simplifies the transition from concept to reality—ensuring right-first-time results and reducing costly back-and-forth in design.
"Designing a part for RTM requires careful optimisation—incorporating ports, seals, resin gates, interlocks, flanges, locators, and more. It can often feel like a ‘black art’, with critical elements missed or errors introduced simply due to the complexity and number of steps involved in tooling design. At MPM, we’ve developed a clear, step-by-step process and checklist to take customer CAD files through to fully finished RTM tooling. This structured approach—covering part optimisation, RTM pattern creation, and final mould development—ensures consistency, quality, and confidence that the approved CAD will deliver the intended result. By working closely with our customers and applying this templated process, we’re able to deliver GRP parts that meet requirements right first time, on time, and often ahead of schedule." - Peter Occardi, Principal Engineer at MPM.
What Makes MPM’s RTM Process Different?
The tooling stage is an area where projects can lose time and accuracy in industry. Our approach supports to fix that. From a CAD file, we walk each project through a systematic flow:
- Part review and RTM (process) suitability assessment
- Design for manufacture: adding gates, seals, ports, flanges, locators
- Pattern and mould design using templated workflows
- Tool production with process controls built-in
This means customers don’t have to be RTM experts—we bring the expertise, reduce the unknowns, and deliver production-ready tooling that meets spec the first time, increasing general supply chain efficiency and predictability for our customers.
The Value of RTM
Compared to open-mould processes like hand lay-up, RTM offers:
- Superior surface finish on both mould sides
- Stronger, more consistent parts due to better fibre-to-resin ratios
- Cleaner manufacturing with reduced emissions
- Greater repeatability for medium-to-high-volume production
However, without the right tooling approach, it’s easy to miss the mark. That’s where our internal procedure shines—reducing design errors, shortening lead times, and producing moulds that just work.
Want to explore whether RTM is right for your GRP project?
