Plastic bushings to replace bronze bearings

Plastic bushings have already replaced sintered bronze bearings in thousands of applications from a wide range of different industries, including agricultural machinery, lawn mowers, medical equipment, food processing machinery, fitness equipment, pumps and valves, and many more.

Oil-impregnated sintered bronze bearings rely on a capillary action to create a lubricating oil film. Critically, however, high speed and rotational motion are both required to draw the oil out and maintain a full film of lubricant. Shaft oscillation, slow speed and intermittent use can all inhibit this process.

If movement stops, the oil on the surface of the bearing dries up. This can lead to squeaking and an increase in the coefficient of friction. High temperatures can also break down the oil.

Further disadvantages with this type of bearing include low chemical resistance and sensitivity to dirt, edge pressure, and impacts.

Another consideration, whether you are using plastic bushings or sintered bronze bearings, is which shaft to use. This is the most important factor after the bushing material has been determined. This is because it is in direct contact with the bearing and is affected by relative motion.

A shaft that is rough is too abrasive and will separate small particles from the bearing surface during movement. On the other hand, very smooth shafts can lead to higher wear because not enough lubricant can be transferred onto the shaft to have an effect.

Sintered bronze bearings function best on very hard, expensive, precision ground shafts. In contrast, plastic bushings can run on all types of shafts.