Rapid injection molding is exactly what the name implies, but multiplied by a factor of 10! It is hard to imagine that anyone could offer a service that can guarantee a fully functioning injection mold in a day or two, but that is actually the case.
This is precisely what rapid injection molding is all about. Rapid, as in very rapid! These molds are made of high grade aluminum and can produce anywhere from a few parts to thousands. Injection mold making is typically rather slow because the mold making process is so complicated.
Personally, I have worked on many aluminum molds that produce high quality custom plastic prototype parts even after several hundreds of thousands of cycles. At first I was highly skeptical, but after several years of making injection molding prototypes it became routine.

Rapid injection molding requires that you reduce the details of your part to the essentials, in order to facilitate easier machining.
How does rapid injection molding work?
It works by automating as much as possible in the mold making procedure. By taking the customer’s 3-D model and automating the design and manufacture of the mold, the lead times are cut down to a fraction of the conventional process, including stereolithography prototypes.
One of the central parts of the automation process lies in the design of the plastic part. By working with knowledgeable designers, many features, such as undercuts, can be minimized or eliminated
Rapid injection molding costs and considerations
- Part draft angles and radii
- Ejection
- Using straight pulls whenever possible
- Simple approaches to side actions
- The CNC milling process
- Part size limit
- Part draft angles and radii

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Advantages of rapid injection molding
- A way to bridge the time gap between prototype and full production. If you need a working injection mold right now, this is the answer.
- Short run production to get your product in the marketplace immediately.
- Gives engineers a working model to approach a full-blown design for a production tool.
Disadvantages of rapid injection molding?
- The aluminum molds are low production.
Works best for simpler parts with minimal side action and undercuts. - EDM machining is eliminated, thus some detail may be sacrificed.
- The entire core and cavity are high-speed CNC machined, often on 5-axis CNC machines, therefore the design has limitations.