How bearings fail - electrically

Important information is given for the control and prevention of: electrical erosion damage in rolling element bearings, a phenomenon not always readily recognised in bearing failures.

Important information is given for the control and prevention of: electrical erosion damage in rolling element bearings, a phenomenon not always readily recognised in bearing failures.

What is electrical erosion? Under certain application conditions an electrical current may pass directly through a bearing during its passage to earth.

Electrical current transfer of this nature can invoke potentially catastrophic damage to rolling bearing contact surfaces.

Electrical erosion is a relatively common occurrence with bearings operating in electric motors, railway traction motors, electrical generators as well as bearings in industrial process equipment where a static electrical charge may inadvertently be generated.

How does electrical erosion damage occur? Conventional lubricating greases behave largely as electrical insulators rather than electrical conductors within the bearing offering resistance to the transfer of electrical energy.

Irregular electrical transfer however does occur resulting in the development of spasmodic electrical arcing across the bearing hertzian contact points.

Molten craters are formed at these points resulting in the development of the classical "washboard" line markings clearly seen.

How can electrical erosion damage be prevented? * By insulation of the bearing.

* By use of the tribologically engineered electrically Conductive special grease: Kluberlectric B42-72.

Product development - the electrical conductivity characteristics of a range of lubrication materials was firstly determined.

(base oil, thickener and solid lubricants) via a purpose built test rig.

Special grease formulations were then developed and rigorously tested.

Result = Kluberlectric B42-72, special "optimised" grease formulation with exceptionally low electrical resistance.

Efficient electrical transfer = damage free electrical discharge through the bearing.

Kluberlectric B42-72 can eliminate costly machine failure by prevention of electrical erosion bearing damage.

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