Plastic Components
Most people commonly think of metal products when they consider precision machined parts made on CNC Swiss screw machines, but many types of plastic can be machined from the bar form on screw machines. Plastics, from common to exotic, are used to develop components and prototypes using Swiss turning. Some common grades of plastic that we run include Delrin (acetal), nylon, Teflon (PTFE), polycarbonate, acrylic, PEEK, ABS, and others. It is important to keep in mind that not all grades of plastic are available in bar form. Also, plastics with glass additives create unique and challenging issues on a CNC Swiss screw machine. Typical parts machined from plastic bar stock include bushings, insulators, screws, and more for use in virtually every industry.
ABS is a general, widely used plastic offering high impact strength, toughness, and electrical resistance at a low price. It is also easy to finish, as it can be painted, glued, or welded together. A matte finish will be left on the ABS material when machined, and it can sometimes be shiny, depending on how it is machined. ABS is one of the simplest materials for machines and, therefore, one of the most cost-effective.
Nylon 6/6 is a strong plastic used in a wide variety of applications where durable parts are needed. It has relatively high chemical and heat resistance with the rigidity necessary to retain its shape and strength to resist deformation under loading conditions. Glass-filled nylon is also popular. Nylon 6/6 will also absorb moisture, which will cause it to swell and lose some of its dimensional accuracy. Nylon maintains a high strength and rigidity over a wide temperature range, good electrical insulation, and good chemical and wear resistance. This material is commonly used to manufacture medical devices, circuit board mounting hardware, electrical insulation, and automobile, and aerospace components.
Acrylic is a tough plastic with decent impact strength and scratch resistance and can be easily glued using acrylic cement, although it is a brittle plastic that has the tendency to break easily. Attention should be paid to the wall thickness in acrylic components as thinner walls are more brittle. When acrylic is machined, the machined surface will lose its transparency and take on a frosted, translucent appearance. As-machined, acrylic is transparent and is most commonly used as a lightweight substitute for glass or light pipes. Other common uses include automobile light components, light tubes, tanks, panels, and optical engineering components.
Delrin is a trademarked name for a class of semi-crystalline thermoplastic acetal resin. It has a slippery, low-friction surface, excellent dimensional stability, and high stiffness. This acetal resin has many classifications: standard, toughened, low friction, glass-filled/reinforced, and UV-stabilized. Delrin is a good plastic for these or any other applications that will experience lots of friction, require tight tolerances, or need a high-stiffness material. It has been used in commercial markets for decades due to its reliability and durability. It also has excellent impact, chemical, moisture, and fatigue resistance. Delrin is also easy to CNC machine. Because of its high stiffness and rigidity, Delrin is an excellent choice for CNC plastic machining parts that require dimensional accuracy and tight tolerances. Delrin is commonly used in gears, bearings, bushings, fasteners, jigs, and fixtures for assembly or even automotive, construction, and electronics components.
Polycarbonate, is a durable plastic and is a transparent thermoplastic. It is also one of the most commonly used CNC-machined plastics and one of the most widely recycled plastics globally. It has a natural transparent milky-blue appearance but is commercially available in a black hue. Both the black and milky-blue tints are naturally glossy. Machine-grade polycarbonate provides the transparency and high-impact strength needed for structural applications. Polycarbonate has a very high impact resistance and stiffness, and remains functional over a wide range of temperatures. It is also optically semi-transparent, although it can be dyed black if opaqueness is needed. Polycarbonate is best suited for applications in which a very tough or very strong plastic is needed, or where optical transparency is desired. Because of this, polycarbonate is one of the most used, and most recycled, plastics. Pure polycarbonate does not have good wear resistance and is prone to scratches.
