We have talked about making models before but many people have asked me recently how to start making their ideas come to life, so I thought a little refresher would be in order. When you are working on a new product idea, you will probably need to build a model called a prototype.
There are many ways to make a prototype. If your product is small, think about making it of plastic using a vacuum-forming technique. Vacuum forming is one of the lower cost ways of prototyping.
Make a wooden model to be translated in sequence from a 3-D model into plastic. For example, if you had a small square box about 4 inches on each side and made a wooden model and took it to a company for vacuum forming, they would tell you to redo your wooden model making the bottom of the box about 1/8th of an inch smaller than the top. That process is called “backdraft” and is required because later in the process, when the wooden model is pulled out of the plastic, it won’t be locked in by being the same size at the bottom as the top.
The company will have machines into which you put your model. A thin plastic sheet goes over the model. A heating system on top of the plastic sheet partially melts the plastic and softens it. Then a covering box is settled down onto the mold with the softened plastic covering the mold. A strong vacuum pulls the plastic over the mold very tightly. When cooled you are left with the covering box. You would then lift out your plastic box, trim around the top and there you would have a four-sided box with a bottom.
Of course once you know how a vacuum form system works, you can make your mold any shape or size or configuration you want. Vacuum forming is a low cost method of prototyping because the mold can be made of wood at very low cost. The plastic, however, can become expensive if you need large quantities because of the cost of trimming.
I’ve made many new products that started from a vacuum-formed model. Then later, after deciding the shape was okay, I would sometimes make the molds in a much more expensive technique, called injection molding, where the mold is made full size and thickness and put into an injection-molding machine. The mold is quite complicated and can make either a whole product, like a telephone, or just a part of a product, like the outer case.
When the mold is in the machine, plastic pellets are put in, heated and squeezed to fill the whole mold. When the plastic cools, the mold opens and out tumbles a fully completed part.
While the mold is expensive, in fact, sometimes thousands of dollars, there is no trimming as in vacuum forming so this method can eventually be less expensive than vacuum forming depending on how many items you plan to make.
For your first project learn how to get the best looking working prototype.
Article © Copyright 2002 Stanley I. Mason. Syndicated by Paradigm News, Inc.
