Renaud 175-060196 Bearing failure from contamination
Renaud 175-060196, 8,000 RPM, grease bearing lubrication, belt drive
Bearing failure from contamination, loose drive pulley
The bearings in this tool grinding spindle felt very rough when rotated by hand in assembly incoming. Coolant contamination was found throughout the spindle interior, which caused failure of both the front & rear bearing pairs. An additional factor was that the spring pack was covered with sticky coolant residue which prevented it from providing the proper bearing preload. The drive pulley was found to be very loose on the rear pulley journal of the shaft. Operation of the spindle with the loose fit had resulted in fretting & corrosion of the pulley journal OD. We observed no other significant dimensional deviations in the tooling pilot, on the bearing journals or shoulders, or in the housing bores.
We performed a grind, chrome plate & finish grind of the OD of the pulley journal. When all components had been thoroughly cleaned, we reassembled the spindle with new bearings, setting the proper preload, and replaced the assembly screws. Our final QC process included run up of the spindle to break in the grease, final trim balance and vibration & thermal analysis during test run.