Overbeck 45.60R Spindle Repair

CHALLENGE

The bearings in this grinding spindle were very noisy when the spindle was rotated by hand incoming. During breakdown, it was noticed that the rear bearings would slide on and off the rear shaft journal by hand. The journal was undersized by nearly twice ISO, a condition which if left uncorrected would lead to premature bearing failure. Our dimensional evaluation also revealed excessive runout on the drive pulley taper OD, tooling pilot face, and the front bearing shoulder. The customer did not provide their drive pulley, but from the rub out and signs of heat on the pulley taper, it appeared that there was poor contact between the pulley ID and taper OD. The customer did provide us with a quill which afforded us an opportunity to confirm that the 4µ runout on the pilot face was significant, translating to 52µ runout on the ID taper of the quill when installed in the pilot.

SOLUTION

We remedied the dimensional issues by performing a grind, chrome plate, and finish grind of the rear bearing journal.  We also kiss ground of the drive pulley taper OD, tooling pilot face, and the front bearing shoulder. The parts to be replaced during reassembly were the bearings, bolts, and o-rings.

RESULT

After reassembly of all components, adjusting bearing preload, and undergoing break-in and testing procedures, this spindle passed our final quality inspection before being returned to our customer with a 1-year warranty.