The 5 Major Benefits of Plastic Bearings

Metal-backed, PTFE-based (polytetrafluoroethylene) polymer bearings have a steel backing bonded to a porous bronze sinter layer. The layer is impregnated and overlaid with the filled PTFE bearing lining. This thin lining can be scratched off by contaminates causing metal-to-metal contact between bearing and shaft. This increases the coefficient of friction (COF) causing higher wear rates and shaft damage.

With sintered-bronze bearings, oil is drawn from the bearing as it rotates on the shaft (minimum speed of 1 metre per second). The oil creates a thin film that then separates the bearing and shaft, preventing wear and shaft damage. At high speeds, a low COF is achieved. However, shaft oscillation, slow speeds, irregular use or uneven loads can impede film lubrication from being maintained. As a result, the coefficient of friction and wear rates increase. This type of bearing should really never be used for linear motion.

Self-lubricating polymer bearings contain solid lubricants embedded in millions of tiny chambers of the fibre-reinforced material. During operation, the bearing transfers lubricant onto the shaft to help lower the COF. Unlike a sintered-bronze bushing, polymer bearings release solid lubricants as soon as the bearing or shaft is set in motion. The fibre-reinforced materials inside the bearing withstand any high forces or edge loads. Plastic bearings can also be used on many different shaft types.

Also, it's important not to confuse high-performance plastic bearings with plastic bearings from a local injection moulder. With iglidur® plastic plain bearings, you can accurately calculate the life of a bearing according to wear rates, actual testing results and specific application parameters. igus® provides the Expert System—a complimentary database where users enter the maximum loads, speeds, temperatures, and shaft and housing materials, which then prompts the system to calculate the appropriate plastic bearing and its expected lifetime based on real-world testing.