Rapid Injection Molding: The Need For Speed

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.

Personally, I have worked on many aluminum molds that produce high quality 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.

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.
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.

Some of the features that must be considered are:

Part draft angles and radii
Ejection
Using straight pulls whenever possible
Simple approaches to side actions
The CNC milling process
Part size limits

What are the 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.

What are the 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, therefore the design has limitations.

Is rapid injection molding expensive?
Surprisingly, the cost is quite reasonable, though there is always a premium to pay for extremely quick turnaround. Typically though, the cost is much less than might be expected. This is due to the highly developed automation process of this type of mold making.

Conclusion
Rapid injection molding is a niche market segment of injection mold making. It serves a highly specialized marketplace, yet is very important withing the niche. The ability to get your injection molded plastic part to market in a matter of days is very valuable to the right company.
Also, the ability to bridge the gap between prototype and high production is a very useful tool for custom injection molders.

Randy Hough lives and works in the Upper Valley of Vermont. He has been a master plastic injection mold maker for 30 years, a youth pastor for many years and has traveled and studied extensively in Europe. He also has 8 lively children who have taught him more than anything else. He has a site about dealing with family stress and a /www.global-plastic-injection-molding.com>plastic injection mold making site.