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.

Ultracomp Composite bearings are made using different migratory lubricants. PTFE, Graphite and MOS2 are the traditional lubricants used in these high load, low speed bearings. Historically, MOS2 has been the lubricant of choice in marine environments because of the compatibility of the moly with mating hardware in salt exposure. Graphite would act as a cathodic agent against stainless or other metals when exposed to salt air, salt fog or salt water. Tri Star recommends UC300 with PTFE lubricant as a more universally acceptable material. For dry or wet applications, the PTFE lubricant is an effective agent for low friction lubrication, is compatible with soft mating hardware like aluminum and stainless and has no corrosive effect in the salt environment. Let us know if you have issues with corrosion in your marine bearing applications. We have a solution!

Slide plate bearings provide support and a low coefficient of friction while allowing an object to move (or slide) freely along a supporting surface. They consist of an upper and lower component, and can be used in both guided and free-moving applications.

Slide bearings are engineered to fit anywhere there is the potential or threat of movement, such as bridges, oil pipelines, building footplates, tank farms and petro chemical applications.  For example, the Alaskan pipeline, at roughly 800 miles long, could be subjected to a mile of liquid flow movement(hysteresis) within the structure.  It requires a bearing designed to resist corrosion, temperature extremes and rugged terrain.

Fluorogold slide bearings easily tolerate thermal expansion and liquid flow movement, and hold up well in cold temperatures.  They also absorb vibration and impact, making them a preferred bearing material for use in earthquake zones.

Fluorogold can also be customized to meet exact design requirements and offers outstanding chemical and electrical properties.  They’ve also been tested for and proven resistant to radiation, where neither the bearing strength nor the epoxy bond were impacted by doses as high as 10⁶ rads.

Share your experience with slide bearings.

The Dixon M-Liners from Saint Gobain have become very difficult to obtain since they come from overseas. Tri Star is now offering a size for size equivalent product in it’s Tri Steel product line called Tri Steel PE. This product is a rolled steel backed polymer lined bearing. The polymer liner is a special PEEK/PTFE combination that has a thicker dimension  than normal steel backed bearings. This allows for post machining of the ID to tighter tolerances without removing the primary bearing source. Learn more from Tri Star’s website www.tstar.com and review the information on Tri Steel Bearings or watch our Tri Steel video on the Video Learning Center.

Ultracomp Composite Bearings are designed for extreme loads where impact and vibration may occur. Because of it’s very high impact strength it can take extreme loads as well as shock loads. Ultracomp requires no lubrication which eliminates maintenance, is much kinder to the environment and reduces overall costs of ownership.  Ultracomp absorbs virtually no moisture, takes static loads up to 55,000 psi and handles dirty, gritty environments. Ultracomp is also an excellent underwater bearing for applications as diverse as bowthrusters, rudder bearings, roller bearings, dockside equipment exposed to salt air and water. Also an excellent bearing material for construction, material handling and ag equipment.

Visit our Video Learning Center to learn more about all we have to offer.

The life expectancy of filament wound composites like TriStar’s CJ product can be improved by understanding some of the typical failures. One consideration is the shaft material. In some applications where the motion is oscillating and at variable frequencies, the bearing can experience rapid wear. This is caused by small angle oscillation or small amplitude vibration and the resultant fretting corrosion. The wear debris that occurs can quickly become an abrasive that dramatically shortens life.

There are a couple of possible fixes for this problem. First, consider going to a 400 Series stainless pin. Testing by an independent company showed a 26 times improvement in wear life by making this simple change. The improvement was directly related to the elimination of the fretting corrosion that occurred on the 1215 carbon steel pin used before.

A second fix is improving the shaft finish and hardness. Another test showed that by going to a 50-55 Rc hardness on the shaft and improving the surface finish to 4-6 rms extended the wear life of an application from 500,000 cycles of life to over 1 million cycles.

One thing to look for if you are experiencing rapid wear of composite filament wound bearings is the debris. If the debris is a fine brown powder than the wear is normal. If the debris looks more like shavings or accumulates in large clumps on the shaft, then you may have a shaft material, surface finish or pin hardness issue that needs addressing.

That being said – CJ bearings are crucial for transportation and other roles. Find out more in our Shooting Star Archives!

New TriSteel PE material utilizes the outstanding wear properties of PEEK, combined with the PTFE low friction additive, make this product unique in thin wall metal backed products. The PEEK liner has excellent resistance to chemicals and when combined with a stainless steel shell material it is perfect for applications in chemical pumps, valves or environments where temperature is critical. TriStar’s TriSteel PE bearing is available in inch and metric sizes as sleeve, flange and thrust bearings. Ask the Experts or visit www.tstar.com for more information.

Recent studies have proven beyond question that the surface finish of the mating hardware when using composite bearings will make or break the performance. In a rotary test, the 8rms mating surface finish had a wear rating of 1, at 16rms it increased to 1.4, 32 rms 2.2 and at 63 rms 5.3. It was also noted in the test that the method of finishing also influenced the bearing wear. Roller burnished surfaces performed the best with ground and polished next best. Turned finishes or mill finishes, even at 16rms, tended to have faster wear than the other finishing techniques.

And if that wasn’t enough for you – head over to the Video Learning Center and pick up a few more nuggets of information.