When you design a part, much of its functionality will depend on obvious factors like its shape, size, wall thicknesses, locations of connection points, and so on. Less obvious but equally important will be the characteristics of the material from which it is moulded, machined or 3D printed (cut, bent, shaped, etc.).
Design is done at the macro level; material properties are generally controlled at the molecular level. The earlier in the design process you start thinking about materials and their properties, the more effective and economical your finished design will be. This tip is intended to help you with that early evaluation. It offers an overview of the four general categories of material properties (metals and plastics), some major considerations to keep in mind when selecting materials for your next part design, and some frequently overlooked design issues to consider.
Why Material Choice Matters
Material choice — whether metal or plastic — can be simple, almost incidental, or complex and critical to a part’s performance. Say, for example, you want to produce a case for a device designed for indoor use. A large percentage of plastic shells aren’t particularly thermally or electrically challenged, don’t have extreme mechanical requirements, and so can function in relatively benign environments such as your family room. The majority of such parts can be made from ABS, polycarbonate (PC), or an ABS/PC blend.
On the other hand, consider the housing for a motorcycle’s air cleaner. This will need to be opened and closed periodically for filter replacement. As part of that function it may employ a living hinge or integrated spring clip. It will have to tolerate assault by flying debris, heat from the engine, UV radiation from the sun, moisture from a variety of sources, and chemical exposure from both fuel and cleaning chemicals. Finding the right material for this application will probably take both research and iterative prototyping.
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