Our customer requested that we test run the spindle when we receive it to see if it is need of a rebuild. We ran it at top speed on our test stand and found high overall velocity readings and high acceleration readings. This is indicative of bearings that have passed their usable lifespan. We discussed our findings with our contact and determined that the spindle should be broken down.
Possible cause of failure:
Incoming test run indicated excessive vibration & high bearing spike energy.
Drawbar tube bent (drives rotary union), drawbar force spacer assembly broken, c/s drawbar balls & pins.
Shaft out of the spindle, grippers removed, could not obtain incoming retention force.
Front and rear bearings soon to fail from coolant contamination, grease was partially washed out.
Front housing severely egged -5/+15µ (iso = +/- 7.5µ). Leading edge of taper chipped.
Slight pre-existing rub out between the front housing cover & shaft spacer ring.
Drawbar sensors not supplied.
Clean, inspect overall dimensions.
Replace bearings, bellevilles, and o-rings.
Replace drawbar assembly.
Grind, chrome plate and finish grind the front housing & shaft taper.
Machine out damage on front housing cover & shaft spacer ring.
Adjust preload, balance, assemble and break in. Final quality control inspection.
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Catastrophic bearing failure was the main cause of this spindle malfunction
Continue reading to learn how Northland Tool performed this repair and converted a Weiss GHK 176239 spindle from grease-injected to permanent grease lubrication…