Part 4 - Part Warpage Due to Relieving Internal Stress
In Part 1, I talked about how dimensioning with common stock sizes in mind can reduce costs and save time. In Part 2, I talked about how the shape of the finished part can impact costs. In Part 3, I talked about lowering costs by thinking about inside corner radii and depth during the design process.
Best Practice #7: Design to minimize distortion and warping.
A part like this can be expensive to machine because it can require special attention to prevent distortion and warping. There are internal stresses in raw materials, left over from the extrusion process. When you remove a large portion of that material, you will relieve some of these stresses, and the part may change shape in an unpredictable way. Machinists have tricks to reduce this effect, but it is best to minimize it through design. For the example shown, you might want to consider splitting it into multiple parts.
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