Tech Talk Blog

We see this question often.  Plane bearings offer many advantages; a simple design, self-lubrication, a wide range of operating parameters, and lower cost.

When selecting a plane bearing, consider:

Load – this can be the most difficult attribute to define. What is the pressure? Multiply the ID times the length, and then divide the load by that number. Pressure (P) is expressed in PSI.

Speed – you may know what your shaft speed is, but you need to find the velocity (v). Take the diameter multiplied by pi, then multiply by the RPM. Divide this number by 12, because V is measured in surface feet per minute (SFPM). Every material is rated for a maximum velocity.

P and V – these must always be considered in tandem. The combination of load and speed generates frictional heat. Always review P x V or PV. Every material has a maximum PV rating.

Material Rating – look at all the values for each individual project. Plastics are insulated in nature, and heat will kill a plastic bearing faster than anything else.  Be sure to stay within the known limits to understand what materials are capable of taking.

Temperature – this is critical to getting the proper “press fit”.  Be certain there is no loss of tolerance or close-ins.

You can also visit our Plane Bearing Design Worksheet for guidance, or contact us directly.

Plane bearings are straightforward; two surfaces moving against each other without the aid of a rolling element. A shaft turning in a bushing, a slide pad damping vibration, a bridge joint expanding, and a chain running through a channel are all examples of plane bearings. Sleeve or flange bushings, thrust washers, linear-slide plates, friction bearings, and wear pads all fall into the plane-bearing category. If there are no balls, needles, retainers, or races, it’s a plane bearing.

Plane bearings stand up to most industrial and outdoor applications. They are self-lubricating and offer superior resistance to fresh water, saltwater, deionized water, slurries, acids, or bases. And because they have few moving parts, most plane bearings are not adversely affected by particulates like coal dust, quartz debris, sand, and road ballast. Plane bearings are safe for clean rooms, too, because they produce minimal debris and won’t attract dirt. Many materials also meet FDA, USDA, 3A, or NSF standards.

Our team can walk you through our complete selection to make sure you get the right fit for your application.

Moly filled cast nylon bearings have been used very successfully for many years. The known drawbacks of nylon has always been it’s inherent tendancy to absorb moisture over time and thus causing swelling of the material. More than that, the constant absorption and drying cycle leads to fatigue failure over time. The CJ bearing has zero absorption in moisture, is stronger in terms of compressive strength and resistance to deformation, has a thermal expansion rate the same as steel and has a very low friction. Since the CJ requires no lubrication, it is as close to maintenance free as you can get. In independant testing it was shown that wear life of the CJ is significantly better as well. In rotary wear tests we found that the Nylon/MOS2 had a weight loss of over 180mg after 50 hours. The CJ had 100.5 mg of loss in the same test. Load for the test was 2000 psi at 25 sfpm and temperatures and humidity were controlled in the lab at 78F and 50% humidity. For more information on the CJ Bearing products visit www.tstar.com and check out the Video Library and our on line catalog.