PTFE works very well for rotary shaft seals, but keep in mind that PTFE is available with various fillers that can enhance key properties for your application. In this blog post, we are going to talk about fillers for dynamic PTFE seals and what hardware is most appropriate for that filler.
Advanced EMC Technologies Blog
PTFE has the lowest coefficient of friction of any polymer known to mankind. However, once we’ve added the fillers and additives needed to improve its mechanical properties, it may not have such low friction.
Consider this: virgin PTFE has a coefficient of dynamic friction on the order of 0.04 to 0.06, but adding carbon fiber raises it up to 0.18 and glass can raise it up to 0.5 (yes, about 10x more friction). Fortunately, there are fillers and additives that can improve the coefficient of friction, and we're going to take a look at some of the more common ones.
One additive that works wonders for bring the coefficient of friction down is Molybdenum disulfide, sometimes referred to in the industry as Moly. When added to PTFE with 15% glass fiber, the coefficient of friction goes from 0.5 to 0.15, which is much closer to virgin PTFE. When added to PTFE, Moly is typically combined with bronze or glass to reduce friction and improve wear characteristics.
In its virgin form, PTFE offers some excellent properties such as extremely low friction and outstanding chemical resistivity. However, it doesn’t always have the strength and stiffness needed for applications such as seals or bearings.
Posted in: PTFE Fillers