How A Bearing Failure Can Be Prevented

The search for the damage does not always begin after the warehouse fails, but often well in advance. For example, computer-controlled sensory monitoring can be used on the machine. The highly sensitive devices measure the smallest vibration and the temperature of the bearing. A speed sensor can also be connected. If a device measures deviations or discrepancies, this indicates an irregular run and thus a possible premature failure. Premature failure means that a rolling bearing has fewer running hours than calculated. If appropriate countermeasures are not initiated, a worst-case scenario such as an unexpected machine downtime can occur, which means high losses for every company.

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In the event of an exchange, the affected warehouse is sent by the customer to the wholesaler and service provider Eisenhart Laeppché. The task for the engineers is to classify the damage and determine the causative factors. If the damage to the bearing is obvious, the experienced engineers often recognize the trigger immediately. Visible incorrect runs, for example, indicate installation errors or unforeseen forces.

Cause of failure: lubricant problems

Moisture or dust particles inside the bearing can often be attributed to a damaged seal. Another common cause of failure is lubricant problems. For example, abrasion on the surface or increased roughness of the rolling element raceway is a common feature of insufficient lubrication. Depending on the use of the machines, the temperature resistance of the lubricant is also important. An excess of lubricant can also overheat the rolling bearing and destroy its structure. The sealing and lubricant problems can sometimes even be assigned to "industry-specific" errors, e.g. B. in construction or agriculture, where the bearings are exposed to above average levels of dirt, dust or moisture.

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Another common reason for a bearing failure is an excessive load on the bearing. Bearing loads are primarily axial and radial forces acting on the bearing, as well as speeds, operating temperature and vibrations. If a lower value than the actual value was assumed before the bearing was used, the bearing is heavily overloaded, plastically deformed and the lubricating film can tear off. Misalignments or vibrations also cause unforeseen bearing forces.

Detect the smallest breakouts

If a bearing is used at extreme temperatures, special requirements apply not only to the lubricants, but also to the material. Although the damage pattern is usually relatively obvious, possible causes of a bearing failure may be far more difficult to determine.

Damage analysis uses typical measuring equipment such as hardness testers and perthometers and also special equipment such as a scanning electron microscope. With this sophisticated microscope, the smallest signs of wear or breakouts from the surface can be recognized. If the cause has not yet been identified, the micrograph analysis provides an insight into the material structure or shows e.g. B. oxide inclusions. But micrograph analysis does not always provide clear insights either.

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Materials science investigation

A material science investigation is even more profound. The characteristic light of each element and its content in the material is determined by an electrically generated arc with a spectral analysis. In this way, the purity of the rolling bearing steel used can be determined precisely and a clear statement can be made about the quality of the bearing.

The various external conditions usually act as a combination on a bearing. As soon as the causes of possible failures have been determined, the customer can address them, optimize the bearing life and thus ensure the smooth operation of his machines. (sh)

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SKF is also upgrading Schweinfurt's large bearing production to the most modern level

* Dipl.-Ing. Heiko Wagner is an application engineer at the Laeppché group of companies in Wilhelmshaven