All plain bearing materials have limits in their ability to sustain a given loading at a particular speed. This is known as the pressure x velocity or PV limit. The heat buildup that limits the PV is influenced by a number of factors including:

Coefficient of friction between the bearing and the shaft Loading of surface, expressed as P Sliding speed, expressed as V Ability to dissipate the heat Lubrication and cooling available Dry, wet or immersed application

Vesconite and Vesconite Hilube are internally lubricated and have low friction coefficients. These materials are also polymers, and as such cannot dissipate the heat as easily as metals.
The following equations apply:
  

The load (P) is in Pounds per square inch (Psi)
The recommended design loading for general applications is 4000 Psi for negligible sliding speeds.
  

Surface speed (V) is given as feet per minute.
If there is negligible or no load, the surface speed is limited to 1000 fpm in unlubricated conditions. Higher surface speeds are acceptable when lubricated or immersed in water.

PV is the combination of the load (P) in Psi and the speed (V) in fpm.
The units of PV are therefore Psi.fpm
The level of lubrication that is required is determined by the PV. This lubrication is required to dissipate the heat build-up and to reduce the friction coefficient.

Vesconite can be easily lubricated by grease, oil, water and certain fluids.
Where the application has a PV higher than 10 Mpa.m/min, please contact VescoPlastics.
While many applications do not require lubrication, lubrication is useful as it promotes extra-long life. Even once off initial lubrication at installation gives a better wear life. Simple grooves further enhance life substantially.

Updated  Jan 25 2002