Plastic bearings are used in wet and corrosive environments, clean environments, areas that are difficult to lubricate, and applications that require non-magnetic bearings. Plastic Bearing mades from a variety of plastic materials and are often self-lubricating to provide smooth operation and greater durability. Polytetrafluorethylene (PTFE), a heat-tolerant polymer, is a fluorinated thermoplastic with outstanding chemical resistance, low leachability, and excellent lubricity. Teflon® , a registered trademark of DuPont Dow Elastomers, is a proprietary form of PTFE used with many plastic bearings. Nylon, a category that comprises several grades of polyamides, is commonly used as a bearing surface material because of its toughness, resistance, and pressure ratings. Semi-crystalline acetal polymers offer excellent lubricity, fatigue resistance, and chemical resistance; however, they suffer from outgassing problems at elevated temperatures and become brittle at low temperatures.
Specifications for plastic bearings include bore size, outside diameter or length, and overall width of height. The bearing industry uses a standard, numbered system to identify plastic bearings with metric diameter bores. Bore sizes 00 (10 mm), 01 (12 mm), 02 (15 mm), and 03 (17 mm) have the smallest diameter bores. For bore sizes 04 (20 mm) and up, multiplying the bore size by five yields the bore diameter in millimeters. Hexagonal bores are measured across the flats. Tapered bores are measured by the smaller diameter. For housed bearings, the outside diameter includes the housing. For flanged devices, the outside diameter excludes the flange. The overall width includes the locking collar (if any).
There are many types of plastic bearings, such as plastic ball bearings, Angular contact plastic bearings, Radial ball plastic bearings, Flange-mounted plastic bearings, Hanger plastic bearings, Linear plastic bearings, Pillow block plastic bearings, Cylindrical roller plastic bearings, Spherical roller plastic bearings, Plain plastic bearings and sleeve plastic bearings, Tapered roller plastic bearings, Takeup plastic bearings, Thin-section plastic bearings, but the most widely used is plastic ball bearings
There are 10 good reasons to use plastic ball bearings
1. CORROSION RESISTANCE:
Most bearing failures today are caused by corrosion. Plastic ball bearing can be utilized in environments destructive to conventional bearings. They can operate in hostile environments such as sea water, film processing solutions and swimming pools. In many cases the medium can be used as a lubricant.
2. LIGHTWEIGHT:
Plastics are five times lighter than steel, thereby reducing the weight and energy required to move them.
3. DESIGN FLEXIBILITY:
Special designs are readily and inexpensively made from plastics. This allows engineers complete freedom to design the bearing around the device rather than attempting to design the device around a limited range of standard bearings.
4. PRODUCT INTEGRATION:
Many times a bearing is mounted into another part, such as a plastic pulley, sprocket, wheel or a mounted block. Utilizing the design concept of a plastic ball bearing, can integrate the mating component as the raceway of the bearing, ie: pulley as the outer ring, or the shaft as the inner ring. The end result is fewer parts, reduced assembly time, and overall lower cost.
5. NON METALLIC NON MAGNETIC:
Plastic ball bearings become completely non magnetic when fitted with either polymer, glass, or non magnetic 316 stainless balls. They are ideal for use where there can be no magnetic distortion.
6. HYGIENIC:
Plastic ball bearings are naturally clean because they do not corrode or require lubrication. They are ideal for wash down applications and clean room environments.
7. NOISE CONTROL:
Plastics have the inherent ability to dampen vibrations. Add lubrication and they become virtually silent.
8. SHOCK LOAD SUPPRESSION:
Plastics absorb shock loads better than metal due to their elastic nature. Many conventional radial ball bearings fail due to brinelling of the raceway, ie: balls denting the raceway.
9. LUBRICATION FREE:
There are three reasons steel bearings require lubrication; to reduce friction, dissipate heat and resist corrosion. Plastic, by nature, does not corrode. Due to the design of plastic ball bearing, there is no metal to metal contact, resulting in less friction; therefore dissipating heat becomes less critical.
10. LOW INERTIA FREER TURNING:
Plastic ball bearing runs freer and naturally have low inertia due to the low coefficient of friction between plastic and stainless. Two other factors contributing to low inertia are the ability to run without grease and being lighter in weight.
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