Advantages
Plastic bearings are a better choice:
1.Handling edge loads. Plastic is more flexible than metal, so plastic bearings handle edge loads well. Metal bearings can shatter under edge loads that plastic bearings can handle. However, this flexibility can become a weakness if precision is required. Metal bearings can achieve a level of precision that plastics cannot.
2.For self-lubricating, maintenance-free operation. Plastic bearings can be made with solid lubricants embedded in them. For these bearings, no additional grease is required, reducing maintenance and costs over time. They also eliminate dripping grease, which is a safety hazard in food handling applications and can cause slips for plant personnel. And plastic bearings do not corrode.
3.To reduce weight. Plastic bearings are lighter than metal bearings. This could be beneficial for cars, trucks, airplanes, and other applications where even a gram difference in weight matters.
Disadvantages
Plastic bearings should not be used in the following cases:
1.extreme loads. Compared to metal, it's not surprising that plastic has the highest point in load capacity. However, where this line is drawn may surprise you. Some plastic bearings can carry loads of up to 2,600 pounds-the weight of a small car. However, as loads become more extreme, metal bearings become a more suitable choice. Metal bearings can handle pressure velocity values (psi x fpm) up to 3,000,000.
2.Sustained extreme temperatures. While plastic bearings can perform well in temperatures approaching 500°F for short periods of time, they cannot handle the extreme temperatures of long-term operation. Metals, on the other hand, can handle thousands of degrees Fahrenheit above zero and hundreds of degrees below zero.
3.High RPM. Plastic bearings can withstand low speed, high load and high speed or low load. Unfortunately, at about 500 rpm, the plastic bearings can no longer hold their shape. At these high speeds, metals perform much better.