One of the biggest challenges in prototyping is making a model of a product that has a living hinge. Many methods have been tried. You can make a hardmodel, rubber mold it and cast a low durometer casting that will allow you to flex a hinge a few times before it breaks. We used to make a living hinge out of thin polypropylene sheet stock and screw that in place to act as the living hinge.
With the advent of rapid prototyping, there have been many attempts to get a printable material that will represent a polypropylene part, but none that I have seen would last more than a few bends of the hinge. That left us with a good clear tape as the best solution to represent a living hinge. None of these were great solutions. So why can’t you cut a polypropylene part on a CNC machine?
Polypropylene is a very flexible soft material. It has a very low melt point as well. These factors have prevented most people from being able to machine this material. It gums up. It starts to melt from the heat of the cutter. It does not cut clean and if you can machine it, it needs to be scraped smooth to get anything close to a smooth surface. Everyone has always told me to just forget it, you can't machine polypropylene.
Our talented team at Creative Mechanisms have solved the problem. Yes, they figured out a way to machine polypropylene. They can machine it cleanly with great detail. They can machine snaps that are functional. They can machine a living hinge down to .005 of an inch. The results are amazing.
There's only one problem. No one believes me. I tell prospective clients we can do this, and they tell me to my face: you're wrong. It's impossible. I have to show them our physical prototypes before they realize we actually figured out how to machine polyproplene.
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