When machining plastics, it is important to consider that the heat conductivity of these materials is only one hundredth to one thousandth of that of metals. Plastics tend to lose heat more slowly than metals and in order to avoid local melting and gumming, we machine plastics with a high cutting speed, a low feed rate, and sharp, well polished tools.
Plastics typically have a high thermal expansion coefficient, up to 10 times greater that that of metals. At Aline Components, we take this into consideration prior to machining and measure the dimensions of machined plastic parts or components after they have cooled. During machining, internal stresses can develop in the plastic part or component. In critical cases, we may consider annealing to prevent environmental stress cracking.
Aline Components knows what fixtures, tool materials, angles, speeds, and feed rates to employ in precision plastic machining to obtain optimum results. We use standard high-speed steel tools or carbide tools, which are generally used for machining metals; as well as tools specially designed for plastics. Each tool type has its own set of unique benefits, however, tools designed for plastics allow higher production rates and better chip removal capabilities. Carbide tipped tools and diamond tools offer a longer tool life and are ideally suited for filled polymers. To minimize frictional heating our cutting tools have a generous back clearance.