Functional parts that carry load and move from 3D printing

The key difference between a functional part and a plain housing part lies in the anisotropy of the FDM process. A printed part is inherently weaker between layers than within a layer, because the bond between two consecutive layers never fully reaches the strength of continuous material. For a gear, a lever or a guide, orientation in the build volume therefore determines whether the part survives its intended load or cracks along the layers.

Wear is the second factor that sets functional parts apart from static components. Gear flanks, sliding surfaces and bearing points rub against a counterpart during operation, and the layered structure of a printed surface behaves differently from a machined or ground surface. Fiber-filled materials such as PA12-CF or PA6-GF significantly reduce abrasion but do not replace a material pairing designed for very high cycle counts. For safety-relevant or very heavily loaded continuous drives, we recommend running a wear test in the actual application before ordering larger quantities.

In the design itself, simple rules help more than complicated calculations. Fillets instead of sharp corners at loaded transitions distribute stress peaks, wall thicknesses from 0.8 mm avoid failures at thin spots, and snap fits should have generously sized bend radii so the latch does not fatigue within the first cycles. Where possible, we print a functional sample before the series run and test it under real conditions, because friction, play and noise behavior are judged more reliably on the finished part than from pure CAD geometry.