PTFE – N
The coefficient of friction of plastics is usually measured against polished steel. PTFE’s coefficient of friction is 0.03 â€“ 0.1, which is the second lowest of any known solid material (Diamond-like carbon being the first).
Sheet, Rod, Moulded Cylinder
PTFE has excellent dielectric properties. This is especially true at high radio frequencies, making it suitable for use as an insulator in cables and connector assemblies and as a material for printed circuit boards used at microwave frequencies. Combined with its high melting temperature, this makes it the material of choice as a high-performance substitute for the weaker and lower melting point polyethylene that is commonly used in low-cost applications. Itâ€™s extremely high bulk resistivity makes it an ideal material for fabricating long life electrets, useful devices that are the electrostatic analogues of magnets.
Because of its chemical inertness, PTFE cannot be cross-linked like an elastomer. Therefore it has no “memory,” and is subject to creep (also known as “cold flow” and “compression set”). This can be both good and bad. A little bit of creep allows PTFE seals to conform to mating surfaces better than most other plastic seals. Too much creep, however, and the seal is compromised. Compounding fillers control unwanted creep and improve wear, friction, and other properties. Sometimes metal springs apply continuous force to PTFE seals to give good contact, while permitting some creep.
Due to its low friction, it is used for applications where sliding action of parts is needed: bearings, bushings, gears, slide plates, etc. In these applications it performs significantly better than nylon and acetal; it is comparable to ultra high-molecular weight polyethylene (UHMWPE), although UHMWPE is more resistant to wear than Teflon. For these applications, versions of Teflon with mineral oil or molybdenum disulfide embedded as additional lubricants in its matrix are being manufactured.
Formulations of PTFE include infusions with glass, carbon and bronze and other fillers, giving it added properties while allowing it to retain most of its unique characteristics.