Author: Sara Mccaslin, PHD
There are so many options for bearings and bushings on the market today, including metal, polymer, and composite.
In this blog post, we are going to take a quick look at composite bearings, including what exactly qualifies as a composite bearing and how their performance compares to other types of bearings and bushings.
Types of Composite Bushings and Bearings
Exactly what is meant by the term “composite bushing” can vary according to manufacturer. For example, there are composite bushing designs that combine a steel backing with a sintered bronze layer covered with a polymer lining such as PTFE. There is also a more classic approach to composite bushings that combines a polymer resin with glass fibers, often filament wound, and a PTFE lining to reduce friction and provide lubrication.
3 Benefits of Composite Bearings
The goal of a composite bushing is to combine the best properties of multiple materials. For example, a steel backing provides additional strength, stiffness and durability but on its own doesn’t have the right tribological properties to be an effective bushing.
1. Strength and Stiffness and Low Friction
When a steel backing is combined with PTFE or POM, the strength and stiffness properties are enhanced by the low friction of the polymer material. The use of a polymer layer such as PTFE also deals with issues such as corrosion and unwanted chemical interactions by providing protection the metallic layer(s).
2. Many composite bearings are, by their very nature, dry-running.
They can be designed so that no grease or lubricant is required, which can be very important for applicants that are sensitive to contamination or other instances where grease could pose a problem. When designed correctly composite bearings can provide extreme low friction, almost eliminate issues with stick-slip, and reduced break-away torque requirements.
3. Dimenstional Stability
Another issue that composite bearings can address quite well is dimensional stability.Some polymers are especially susceptible to dimensional changes through absorption of water or reactions to temperature variations. The use of composites can significantly reduce those problems.
Composite Options for Bushings and Bearings
When it comes time to select a bushing or bearing for a particularly sensitive application, it might be wise to add composites to your list of potential bearing materials. Composite bearings may be primarily metal with a low-friction polymer lining, or they may be filament wound fiber reinforced materials with a polymer matrix. Regardless of which type of composite bearing is under consideration, remember that they can offer added benefits such as improved strength, stiffness, wear properties, and reduced friction while possibly eliminating the need for lubricants.