Check it Out: Tips for Rapid Injection Molding Design

I just read the June edition of Design Tips for Rapid Injection Molding. Online rapid injection molded part service provider Protomold has been creating this PDF-based e-newsletter since June 2011. Probably because it got out of hand. See, my contacts at Protolabs, the parent company of Protomold and the Firstcut CNC-machining service for small runs of custom parts, tell me that this e-newsletter is pretty popular among the designers and design engineers who avail themselves of the company’s services a lot or even occasionally. And it’s easy to figure out why they like it: This is a pretty darn good effort. Here’s why.

On a purely curmudgeonly level, the first thing I like about this 23-page document is that it begins and ends on topic. That is, except for the cover and a hyperlinked table of contents, it’s all tips and tricks. No baloney. The second thing that endeared the document to me is that seemingly all of it is of universal interest to anyone working with injection molding.

The June edition offers 12 main topics, all of which provide some level of guidance for designing for plastic injection molding. The paper assumes that you have some familiarity with molding design but you’re not yet in the injection molding design hall of fame. Among the topics are designing clips, eliminating unnecessary material, text, crush ribs, bridging tooling, and injection-molding gears.

Each segment is short and sweet and well illustrated. Like the document as a whole, no topic wastes any time. It focuses right in on the point or two it’s intended to address. Links to videos as well as supplementary information are often provided. For example, the two-part clip design discussion looks at hooked cantilever clips first and explains your lock and release options. It also has a link to a video on spring clips. The second part serves as a quick round up of other snap fasteners, such as annular snaps, torsional snaps, and compressive snaps.

The crush ribs piece was interesting, due to my ignorance of it. Crush ribs are for those times when your design intent does not allow for draft. This technique provides both draft for the molder and the kind of alignment you’d get with a straight-sided hole. The company says the technique is fast, effective, minimizes complexity, and cost-effective.

Naturally, this e-newsletter has tips for the Protomold user as well. But even here it has universal appeal. Take the section on the company’s complimentary ProtoQuote price quote capability.

Now, as you might guess, ProtoQuote gives you a fast quote on what a run would cost. But you can also receive a complimentary design analysis that helps you determine how to improve your design’s moldability. You can use ProtoQuote to interact with material options to see how they affect pricing, moldability, and the like. You can use this capability before you’re fully settled on a design, if you’re considering a machined part, or even if you have a 3D printer in house or a contract with your cousin’s shop down the street. It doesn’t matter. ProtoQuote is there to help you make a better design as well as determine your costs. It sounds worth checking out in and of itself.

Design Tips for Rapid Injection Molding is a no-charge, monthly that’s e-mailed to you. It is well written, well designed, and well laid out. It’s a tidy piece of work.

You can download a complimentary copy of the June edition of Design Tips for Rapid Injection Molding from the link over there. Alternately, hit the other link over there to sign-up for download access to all 9 volumes of the e-newsletter as well as the June edition that we discussed today. Either way you opt to go, Protomold has created a handy reference series on designing for rapid injection molding design that I think you’ll enjoy.

Thanks, Pal. – Lockwood

Anthony J. Lockwood

Editor at Large, Desktop Engineering

Download: The June Edition of the Design Tips for Rapid Injection Molding

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