Faster process to make complex plastic prototypes

The Challenge

Whilst others have shown 3D printing of injection mold tooling is feasible for simple parts, we wanted to mold real world, complex components.

So we developed a fresh approach using industry standard polymer 3D printers to create complex mold tools in hours. Realizing that making the tool is only part of the time required, we also made sure to fast track tool design and verification.

First the design is sketched to develop the geometry of the major components.

The printed tool insert splits to allow the molding to be removed.

Precision 3D scanning is used to verify the accuracy of the finished part.

Our Approach

Others had shown that 3D-printed tooling could work for simple parts, so we started from a clean sheet to handle complex components. Printed polymers are weaker than tool steel and handle heat poorly, so our tooling design works around those limits.

We print only a small insert and fit it into a standard metal mold plate. Prototype tools don’t need to run automatically, so the insert is split into pieces and opened by hand, with no moving parts. Supported by rigid metal, the insert stays mostly in compression during injection, which keeps it accurate. For higher-temperature plastics, we fill it with a low-melting-point alloy to add heat capacity.

Every step is digital, from 3D CAD to printer to our BOY 22-tonne molding machine, with high-resolution 3D scanning to verify both the insert and the finished part. We proved the process on a precision multi-dose syringe made from ABS moldings.

The value we created

Digital tooling closes the gap between fast 3D-printed parts and slow prototype injection molding. Conventional tools take 12–16 weeks and machined aluminum prototype tools 2–8 weeks, but digital tooling delivers verified molded parts in 2–3 days.

Parts are molded in the real production material, so we can test properties 3D printing can’t reproduce, such as biocompatibility, creep, thermal performance and effects of the molding process itself.

This is especially valuable for complex medical consumables. Getting accurate parts into testing earlier means problems surface while they’re quick and cheap to fix, shortening time to market and improving the final design.