Virgin PTFE has outstanding chemical resistance and the lowest friction of any solid polymer, plus a compressive creep problem that makes it a poor choice for anything under sustained load. Fillers exist to fix that, and each one trades something away.
Glass fibre, usually at 15 or 25 percent, gives the biggest improvement in creep resistance and compressive strength for the money, and keeps chemical resistance almost intact. It is the default for gaskets, bearings and pump components. The downside is that it raises the coefficient of friction and is abrasive to a mating metal surface.
Carbon and graphite give better wear performance and thermal conductivity, and unlike glass they do not scratch the shaft. Carbon-filled PTFE is the choice for dry-running bearings. Bronze gives by far the highest thermal conductivity and load capacity, which is why it appears in hydraulic seals and piston rings — but it is not suitable for chemical service because the bronze will corrode. If you tell us the media, the load and the speed, we can usually name the filler in one reply.
Need a material recommendation?
Send us the application and we will reply with two or three candidate grades and a price.
