This is a good example of the typical urgent repair requests we get day-to-day. A large food ingredients company based in Manchester has a 200Kw motor that was failing. Bearing damage was picked up during a condition monitoring route on a critical pump application. The only downtime acceptable to them was overnight.
We collected the motor and carried out our investigations that included an initial test run to confirm our customer’s reported faults. We did indeed see severe bearing distress on both bearings.
The motor was stripped down and this is where we differ from most repair companies, we fully dimensionally check all bearing fits with a coordinate measuring machine (CMM) to check for correct fits and tolerances against an ISO fit table. The bearing housing and journals were within tolerance.
We could have just fitted new bearings and assembled the motor here but at Fletcher Moorland we want to understand why bearings fail.[I learnt a valuable lesson from a very wise customer, He told me “Bearings aren’t clever enough to fail on their own, and something must have caused it”]
Our engineers are trained in recognising bearing failures to ISO 15243:2004. We dismantled the bearings and saw the classic signs of electrical discharge damage, the fluting pattern. We confirmed with our customer that the motor was being run with a VSD and suggested fitting an insulated bearing to help prevent this damage again.
An SKF Insocoat 6319 c3 / VL0241 bearing was fitted to the non-drive-end. After further checks on the motor windings were carried out and the rotor was balanced to an enhanced G1.0 balance grade the motor was assembled, fully tested and delivered back to our customer.