Playing bearing detective

Question: Can I get a clue to an ongoing bearing problem by dissasembling it?

Answer: You certainly can. As bearings rotate, the raceways of the inner ring and outer ring make contact with the rolling elements. This results in a wear path on both the rolling elements and raceways.

Running traces are useful, because they indicate the load conditions. They should be carefully observed when bearings are disassembled.

If the running traces are clearly defined, it is possible to determine whether the bearing is carrying a radial load, axial load or moment load. Additionally, running traces can help determine the accuracy of bearing roundness, confirm whether unexpected loads or large mounting errors occurred, and shed light on probable causes of bearing damage.

For example, when misalignment exists between the inner and the outer rings, the application of a radial load causes running traces to appear on the outer ring, as shown here.

Other examples of typical running traces for roller bearings and deep groove ball bearings can be seen on www.tec.nsk.com. Click on Troubleshooting and select Load/Contact Patterns.

Thanks for this tip go to the bearing experts at NSK Canada Inc.