What is Bearing Brinelling?

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All bearings have a typical service life. However, an OEM’s suggested service life is not always a guarantee. Bearing failure comes in many forms, such as corrosion, smearing and brinelling. The definition of brinelling is the permanent indentation of a hard surface. Bearing brinelling occurs when the internal raceways of a bearing have been permanently damaged. The indentations can quickly lead to improper operation, like chattering or excess vibration, which in turn can accelerate other forms of wear. Two common forms of wear are galling, the adhesion between sliding surfaces, and spalling, the flaking off of materials under rolling pressure. Brinelling causes wear in which, similar marks are pressed into the surface of a moving part, such as bearings or hydraulic pistons. It is usually undesirable as the parts often work with other parts close to each other.

Brinelling is named after the Brinell scale of hardness, in which a small ball is pushed against a hard surface at a preset level of force. The depth and diameter of the mark that is left indicates the brinell hardness of the surface.

Brinelling of bearings comes in two types, true brinelling and false brinelling.

True Brinelling

True brinelling is caused by shock or excessive loads due to improper mounting, dropping of machinery during handling, excessive static or impact loads during the operating cycle. The signs of this type of brinelling are regularly-spaced indentations in the bearing raceway and rolling elements, and an increase in vibration.

False Brinelling

Bearing demonstrating false brinelling

False brinelling is caused by vibrations acting on the bearing while in a non-rotating state and may occur on new equipment which has been carelessly transported. The signs of this type of brinelling, as seen in the image to the right, are depressions and wear marks in the bearing raceway along the axial direction. These depressions cause more noise and eventual fatigue.

How to Prevent Brinelling

Brinelling is typically caused by a heavy load resting on a stationary bearing for an extended length of time. Both true brinelling and false brinelling have different preventive methods. The best way to prevent bearing true brinelling is to avoid unnecessary shock or high impact loads, and isolate the bearings from any external vibration. When looking into bearing false brinelling prevention, reduce or eliminate external vibration and ensure the shaft has been properly blocked and packaged during shipment.

By understanding what brinelling is and how to identify its symptoms, you will be able to help prevent premature bearing failures. For more information on Rexnord Bearings such as installation manuals, videos and product specifications, click here.

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Jason  Ludwig

Jason Ludwig is the Application Engineering Manager for Rexnord's Bearing Division. He has been with Rexnord since 2005 in roles of increasing responsibility. Jason works closely with Rexnord’s customers helping to troubleshoot issues, provide onsite support, train personnel, and select bearings that fit the customer’s needs. As the Application Engineering Manager for Rexnord Bearings, he is an expert on all bearing products that Rexnord provides.