By Brad Cleveland, Protomold
A lot of information is required to create a prototype. At the same time, however, a prototype embodies information — so much, in fact, that there is no other way the equivalent information could be stored and conveyed. This information falls into four categories: form, fit, function, and feasibility.
Form is how a part looks and feels. Take one of the most common plastic parts we encounter in a day, the shell of an electronic device. We may not consciously notice, but its shape, texture, appearance, perceived weight and even temperature are all critical to our experience of the product. Shape can be approximated by a variety of processes, but the other factors depend on the material from which, and process by which, a prototype is made, which is a good argument for using production-type materials and processes.
Fit, of course, is how a part interacts with other components. Do the edges and bolt holes line up? Do the snaps hold? Are the seams waterproof? What looks right on paper or screen may not work after the resin shrinks or warps, if fine features don’t hold, or if the resin isn’t as rigid as expected. As with form, answers can only come from a prototype made of the material and by the process that will be used in production.
Function—the strength, elasticity, chemical resistance, and other performance measures—of a part must be determined by testing, and depend heavily on the characteristics of the resin from which a part is made. Production parts can be made from hundreds of resins. Prototyping processes like Protomold’s injection molding and First Cut’s CNC machining also offer a wide variety of resins. But layering processes like stereolithography, selective laser sintering, and fused deposition modeling require very specific resins and probably not those that will be used in production. As a result, prototypes made by injection molding and CNC machining give more accurate information regarding function than layering processes can.
Finally, there is the matter of feasibility. This is how successfully and cost-effectively parts can be made by your chosen production method. Clearly, a prototyping method that uses the same materials and process as the production process, as Protomold does for injection molding and First Cut Prototype does for CNC machining, will help answer those questions. Other prototyping methods cannot.
Bottom line? The earlier in the development process you introduce the materials and processes you will use in production, the sooner you’ll be able to identify and address issues of form, fit, function, and feasibility.
About the Author
|Brad Cleveland, President and CEO
The Protomold Company, Inc.
1757 Halgren Rd.
Maple Plain, MN 55359 – USAPhone: 763 479 3680
Fax: 763 479 2679
|Brad Cleveland has been the president and CEO of The Protomold Company, Inc. since November of 2001. Prior to Protomold he was cofounder and vice president of AeroMet Corporation, a laser additive manufacturing company and subsidiary of MTS Systems Corporation.Protomold®, a Proto Labs service, is the world’s fastest source for custom injection molded parts. The company fills a unique niche in the manufacturing of plastic parts, using a combination of advanced, proprietary software and sophisticated equipment to produce prototype and low volume runs of custom injection molded parts. The material properties of Protomold’s real molded parts surpass those of parts produced by additive prototyping processes. At the same time, delivery is faster and costs are lower than those associated with traditional injection molding.|
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