The Protomold Process

What exactly is rapid injection molding?

At Protomold, we have automated the process of designing and manufacturing molds based on customer-supplied 3D CAD part models. Due to this automation, we typically cut the lead time for the initial parts to one-third of conventional methods. Cost saving varies with the number of parts being produced, but rapid injection molding may also have a substantial cost advantage in runs of up to thousands of parts.

What do you give up? Actually, very little. Protomold produces quality molds using advanced aluminum alloys and precise, high-speed CNC machining. Parts can be molded in almost any engineering-grade resin.
What's the catch? Not much. Protomold supports an ever-increasing degree of part size and complexity such as many types of undercuts, tall/thin ribs or bosses, off-axis features and more. See our Design Guide for examples.

What's the first step?

Check out the “Step by Step” description of how to work with Protomold. Even if you don't need any parts right now, just give our ProtoQuote system a try and you'll be impressed with the ability to interactively select the number of cavities, surface finish, type of resin and delivery schedule. Every time you make a change, the price automatically updates. This built-in “what if” analysis is like thousands of quotes in one.

Can't believe it?

We hear it all the time: “Nobody can consistently ship real injection-molded parts in a day.” If you're a skeptic, that's ok. Just read through what our customers are saying about our service. Better yet, give us a try for yourself.

The rapid injection-molding niche

The Protomold Rapid Injection Molding process gives design engineers a fast and affordable way to get real injection-molded parts in prototype or low-volume quantities. We work with advanced aluminum alloys and high-speed CNC machining. Our process features an unprecedented degree of standardization and automation, which is how we deliver injection-molded parts faster, and more economically, than anyone else in the world.

This allows us to support prototyping, bridge tooling or low-volume production requirements of our customers as noted below.


Rapid prototyping processes are alright for testing form and fit, but FDM, SLA and the others are no substitute for testing with real injection-molded parts. With Protomold, you can get prototype injection-molded parts for as little as $1,495 and shipped as fast as the next business day (for a premium). Just what you need for function testing before going to production.

Bridge tooling.

When your production tooling won't be ready for another three or four months, it’s great to have a way to make those 100, 1,000 or 10,000 parts for pilot production or market testing. With Protomold, your bridge tooling is ready to go with no additional cost or delay.


If your volume requirements don't justify expensive steel production tooling, Protomold can supply production parts to meet your full requirements. Multi-cavity aluminum molds can be very cost effective, and Protomold will ensure the tools last for the life of your project.

So from an overall market perspective, we see rapid injection molding as in between rapid prototyping and conventional injection molding as illustrated in the figure below.
Market Perspecitve
Also, read the technical paper “Plastics Product and Process Design Strategies,” by David Kazmer, Ruchi Karania and Christoph Roser (.doc, 1.0mb). It's an analytical comparison of various manufacturing processes that support the development of new plastic products.