Surface finishing and coatings

Contact surfaces of rolling element bearings are of utmost importance for performance and service life of the product. Friction of bearings depends lagely on the quality of the surfaces. Therefore racing applications particularly pay attention to the manufacturing quality of the bare surfaces. In some application conditions, specific coatings are used to improve the performances.

Standard bearing finishing process includes grinding plus finishing operations like honing or polishing. These typically generate aligned anisotropic machining patterns. To improve it isotropic surfaces with "lubrication pockets" made by a mechanical manufacturing process were patented by SKF. In this way it is possible to generate super-finished surfaces with extremely low roughness values. Isotropic surfaces can lead to benefit in friction and wear resistance properties, when exposed to marginal lubrication conditions.

Another aspect of optimized surfaces directs to coatings that can be applied to both rolling elements and raceways, and aimed to reduce wear and friction. For this purpose DLC-like coatings as NoWear are invented and used by SKF.

To protect metallic cages made from steel, aluminium or titanium a broad variety of coatings is available, such as silver plating, DLC and anodizing.
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