In David Letterman fashion, we bring you:
Top 10 Ways to Make a Living Hinge Prototype
10. Cut the functional living hinge portion out of an existing production product and, using extremely tiny self-tapping screws, adhere the cut out portion of the hinge to your fabricated model.
9. Using extremely tiny self-tapping screws, adhere a thin piece of polypropylene to the area where the living hinge would be. The material won’t bend quite like a molded living hinge but you will get the idea of how it will work.
8. Fabricate or print your prototype and make a rubber mold from it. Cut the functional living hinge portion out of an existing production product. Insert that living hinge piece into your rubber mold and cast urethane in the mold, embedding the living hinge section in the model as an integral part and hope that it stays embedded for a few bends.
7. Fabricate or print your prototype and make a rubber mold from it. Insert a piece of cloth where the hinge portion would be. Then, cast the part in a low durometer urethane, embedding the cloth. The hinge will be very loose and sloppy but there will be little stress on it.
6. Fabricate or print your prototype and make a rubber mold from it. Cast the part in a low durometer urethane in hopes that the hinge area is flexible enough to bend a few times but the thicker walls are still rigid enough to function.
5. Fabricate or print your prototype and if the side walls are thick enough, you might be able to drill some small holes in them and cast some low durometer material where the living hinge would be and hope that you will get a few bends before the materials separate.
4. Print the prototype in a semi-rigid rapid prototyping material and you will get a few bends out of it before it breaks, which will hopefully give you enough information to get by. It is also inexpensive, so having to print several won’t be overly costly.
3. Print the part in a rapid prototyping flexible material and hope that the hinge area will hold up for a few more bends than the semi-rigid material. Hopefully the rest of your model will be useable with the soft sidewalls.
2. Use a strong industrial tape to connect the parts that would be connected by a living hinge. The hinge is not the same as polypropylene but it will function as a hinge and it is certainly a low cost method that can be repaired quite easily. Creative Mechanisms has been known to use this when the best method is unavailable.
And the number one way to produce a polypropylene living hinge model is:
1. Machine the prototype directly in polypropylene material on a CNC machine. You have probably been told that this is impossible. People have probably said that polypropylene can’t be machined because it’s too soft and melts too easily from the heat of the cutter. Or that it doesn’t cut clean and has burrs and a very rough surface.
Well, it can be done and there is no better way to prototype a living hinge than to produce it directly in the material that it will be manufactured in. You get a model that will function indefinitely – just like the manufactured part. It will have the same feel and the same function as a molded part. The surface finish won’t have the slick gloss finish that a molded part will have, but it will be clean and presentable.
Creative Mechanisms specializes in the machining of polypropylene living hinged models. Let us show you the benefits of a machined prototype.