Current Insulated Bearings

When a stray current in an electric motor uses a bearing as its path to ground, bearing damage can occur. The electrical current passing can cause micro cratering in the raceways of inner & outer rings and on the rolling element surface which ultimately changes the structure of the metal. Below is a picture of damage resulting from electrical discharges.


Once bearing damage from electrical corrosion has begun, increased noise levels, reduced effectiveness of lubricant and excessive vibration will drastically decrease bearing service life. In addition repair work this also incurs additional cost due to machine downtime and lost production. Current passage also has a negative influence on the lubricant

To overcome this problem BMI engineers have developed in collaboration with a university a special ceramic coating which ensures 100% protection and electric insulation. The coating is applied using “plasma spraying technology” to counter the electric pitting. Sophisticated pre & post application processes yield outstanding coating quality which is wear resistant. The coating can be applied on the inner or outer ring depending upon the application.


Taper Roller Bearing 32212-Electrically Insulated-1

The insulation has the guaranteed breakdown resistance for at least 1000V in standard. For higher resistance as well R&D team has developed a special coating to ensure insulation up to 3000V. Currently BMI is serving electric motor manufactures but this type of product is used in Traction motor of railways and wind power generators as well. The material for ring & roller is SAE52100/100 Cr6 but the bearing is manufacture to sustain higher RPM’s for electric motor application

Additionally, BMI is capable of manufacturing cylindrical & taper roller bearing as well with electric insulation.

Typical Application:

  • Traction motor of railway vehicles
  • Electric motors ( AC/DC )
  • Generators ( wind power )

For any other details on current insulated bearings or other technical queries feel free to reach our team on