How to find the right PFPE & Fluid
If your machinery or components are put through hours of brutal abuse, or you simply don’t want to service them too often, then a PFPE grease is probably one of the best investments you can get for prolonging the life of your machinery.
PFPE greases and lubricants are part of a the fluorinated synthetic family and are some of the most thermooxidatively stable lubes around. PFPE’s are slippery and stay put, making them perfect for lubricating hard to reach spots or machinery that undergoes a lot of stress.
As we’ve mentioned in other articles, PFPE’s work wonders, no matter what environment they happen to be used in. So how do you know which PFPE is right for your needs? Well, let’s break it down a bit here.
There are five main types of PFPE: PFPE-K, PFPEY, PFPE-D, PFPE-M, and PFPE-Z. While all types of PFPE grease contain oxygen, carbon and fluorine, each of these is fortified with an additional material which alters the molecular structure. D, M and Z PFPE’s are known as linear while Y and K fall under the pendant molecules. Y and K PFPE’s are known as pendant molecules.
In terms of structure, PFPE molecules are either linear or pendant where a linear refers to the polymers being in a straight chain, almost like a snake.
Viscosity Index, Film Strength and Volatility
While linears are the go-to for when it comes to low-temperatures uses, pendants provide more film strength and increased wear-prevention, especially under extremely heavy loads. The molecular structure of these greases greatly influences their lubricating properties.
Pendent molecules are pretty similar to a 2-dimensional Lego model. Some have branches/chains which makes for a more durable or rigid lubricant. While these branches might make for a less flexible lubricant, they do help form lattices that work to prevent mating parts from coming into contact.
Additionally, linear M fluids compared to other pendants are far superior for lubricating sintered bearings due to their extremely low surface tension and volume of oil within the bearings. Any volatility is dependent on the quality of the bearings. Check out our guide on PFPE grease & base oil viscosity for more information.
Blending with Fluid & Bearings
It’s important to consider the catalytic stability when it comes to a PFPE fluid, especially when used in a loaded bearing, gear or other slow heavy load situations. The catalysis tends to form a residue that can reduce the life or bearings. So it’s important to get a PFPE grease or lubricant that is resistant to catalytic degradation. We recommend a D fluid as bearings lubricated with this fluid tend to show the least signs of wear after use and testing.