Engineering solutions company Renold Crofts says that bearing failure in large machines can often be attributed to the effect of magnetic currents.

There are many factors affecting the lifetime of bearings, regular maintenance and correct lubrication being foremost for process engineers.

However, a little known and hidden enemy of the bearing, which is often overlooked, is magnetic currents. 
Also referred to as eddy currents, these currents are generated by residual magnetic fields in the stator and rotor components of a machine.

The company states that eddy currents are a serious challenge in rotating machinery, and the larger the machine and the higher its rotating speed, the stronger these currents become.

The resulting eddy currents can cause extreme damage to both sleeve and rolling-element bearings and, in some extreme cases, it can cause the bearings to weld together.

The company’s Renold Hi-Tec coup-
ling range of rubber in compression couplings protects the bearings of large rotating machines from eddy current damage.

The combination of the high rubber content of the coupling and the lack of metal-to-metal content between the two coupling halves effectively insulates the motor from the driven machine. This ensures that damaging shaft currents are prevented from flowing from the motor to the bearings of the driven machine.
This prevents costly repair and catastrophic failure.

Machines that are most affected by eddy current damage to their bearings include fans, compressors, turbines and pumps. 
However, any rotating machine 
with bearings can experience this challenge.

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