•Machining
Hinges can be fabricated by machining extruded polypropylene sheet. Care should be taken to
cut the hinge perpendicular to the extruded machine direction in the sheet stock. Machined
hinges should have a similar design described for injection molded hinges.
Conventional cutting tools for wood and metal can be used to machine hinges. Because of the
low heat conductivity of polypropylene in relation to metals, almost all friction-generated heat
between the cutting tool and the polypropylene will be conducted to the metal tool. To minimize
heat and friction, water-soluble oil or kerosene are recommended. Cutting speed should be the
highest possible without overheating the tool. Heat build-up will tend to soften or melt the
polymer, which will then be prone to sticking to the cutting tool.