In a recent conversation with a bearing manufacturer, I gained valuable insights into the world of low-friction bearings. These bearings can significantly reduce surface degradation and friction levels by 30% or more compared to their standard counterparts. In this blog post, we will delve into how low-friction bearings are classified, their importance in various applications, and the materials that exhibit low friction properties.
Understanding the Classification of Low-Friction Bearings
To determine if a bearing is low-friction, we must examine its coefficient of friction (COF). The COF is a key tribological property that measures the resistance between the sliding surfaces of two materials in contact.
Thrust washer tests (or ASTM D 3702) are the most common method for determining the COF of a bearing. These test results allow you to compare the relative "slickness" of bearing materials, with lower sliding resistance indicating a more "slick" material. Tests are typically conducted using unlubricated materials against steel or other benchmark materials.
Friction values are divided into two categories:
- Static COF: The resistance experienced during the initial movement when a bearing starts up from a resting position.
- Dynamic COF: The resistance encountered once the bearing (or mating surface) is already in motion at a given speed.
Many polymer bearings possess the unique quality of having a lower static COF than dynamic. Additionally, materials that utilize PTFE as the primary resin often exhibit lower friction at higher loads. Both qualities fly in the face of conventional wisdom!
The Importance of Knowing a Bearing's COF
Understanding a bearing's friction level is crucial for determining its wear performance and expected service lifetime. To optimize results and extend wear, low-friction bearings should incorporate a self-lubricating design feature. With proper lubrication, a bearing generates less friction, leading to reduced heat and improved overall efficiency in manufacturing processes.
Low Friction Bearing Materials
Composites and polymers offer excellent low friction properties. Rulon® J, for example, boasts one of the lowest COFs, while TriSteel™ bearings can be reinforced with PTFE and other liners to virtually eliminate friction wear. Of course, the specific low-friction bearing material best suited for your application will depend on your service requirements.
Get in touch with our experts to find the perfect low-friction bearing solution for your application!