You wouldn’t judge a potential employee by their grandparent’s track record, would you? Then why let the opinions on flimsy traditional plastics affect the choice between a metal bearing and next-generation engineered plastics?
For years, engineers have chosen steel and bronze bearings, thinking there was no other option to overcome extreme temperatures, heavy loads, and high speeds, not to mention the chemicals, dirt, weather, and other environmental hazards. The truth is, plastics can live up to these demands, often better than their metal Counterparts.
Both plastic and metal bearings have their strongpoints, and before choosing what will work best in your application, it’s important to understand the ups and downs of the options available. With sintered bronze bearings, oil is applied to the bearing, and then drawn out as it rotates on a shaft. The oil creates a thin, greasy film that separates the bearing and the shaft, preventing wear and damage. The downside to this is that slow rotation speeds, irregular use, uneven loads, and many other factors can create problems in creating this oily film, raising the coefficient of friction, or COF, and the rate of wear of the bearing and shaft.
Using some of the benefits of plastic, metal-backed PTFE-based plastic bearings have a steel backing bonded to a porous bronze sinter layer, which is overlaid with the PTFE lining. The thin lining of the bearing can be scratched off by dirt and other contaminants, causing metal on metal contact, increasing the COF and causing high wear rates and damage.
The difference in shaft damage is clear – L: traditional metal bearing, R: iglide plastic bearing
Self-lubricating plastic options, like iglide bearings from Motion Plastics specialist igus, contain solid lubricants embedded in millions of tiny chambers of the reinforced material. As soon as the bearing begins to rotate, that solid lubricant is released and transferred onto the shaft, lowering the COF. Unlike sintered bronze bearings, there is no minimum speed required to release lubrication, and plastic bearings can be used on a variety of shaft materials.
All plastics are not created equal – high-performance plastic bearings are not the same as the plastic bearings from any injection molder. iglide plastic bearings come with the unique ability to accurately predict the life of the bearing, thanks to years of extensive testing in the igus test lab. The online “iglide Expert System” is a unique database, where engineers can enter their application’s maximum load, speeds, temperatures, shaft material, and other factors, and receive complimentary information on the best possible bearing choice, as well as the expected lifetime, based on real-world testing.
A look inside the iglide test lab at igus headquarters
iglide plastic bearings bridge the space between simple plastic bushing and high-tech, reliable machine components. They offer a number of advantages, but here’s five to keep at the top of the list:
1. No more maintenance! On your bearings, that is. Their self-lubricating properties eliminate the need for hours with a grease gun, re-lubricating every bearing individually, and without that sticky grease, iglide bearings are resistance against dirt, dust, and debris, lowering the risk of bearing seizure.
2. Lower your costs. Featuring extremely high wear resistance, a low COF, and the ability to replace costly alternatives in a wide variety of applications, making the switch from metal to plastic can reduce costs by up to 25%.
3. Freedom from messy grease and oil. iglide bearings self-lubricate, transferring tiny particles of solid lubricant into the shaft without increasing the attraction of dirt, dust, and other contaminants.
4. Consistent coefficient of friction (COF). iglide bearings are designed to maintain a low COF consistently over its lifetime. Compared to metal-backed bearings, which can be scratched easily, increasing the COF, iglide plastic bearings often outlast their metal counterparts.
5. Corrosion and Chemical Resistance. Plastic bearings can be used in wash-down applications, under salt water, and in the spray of harsh chemicals and acids without compromising their performance. Water, which can be fatal to the lubricant film of a metal bearing, can be considered an added lubricant for plastic alternatives.
To learn more about igus’ line of plastic bearings, check out this free whitepaper, Plastic Bearings Have Staying Power.
To calculate the best possible bearing for your application, we welcome you to used the iglide Product Selector tool, or request your dry-tech sample box, available for with more than 50 free bearing samples, along with a number of selection cards.