Kessler 000.625.138 Spindle Repair

Kessler is a common spindle manufacturer among the machine tool industry.  They design and sell a wide variety of spindles for all types of machining applications.  This Kessler 000.625.138 spindle is grease lubricated, stator driven, and capable of running up to 10,000 RPM.

CHALLENGE

When this Kessler 000.625.138 spindle arrived at Northland Tool, the first thing we noted was that the bearings felt worn when spun by hand.  The spindle was then fully disassembled and the first part we dove into was the actuator.  Upon taking it apart we recorded that there was a brown sludge inside causing it to not function properly.

Brown sludge in actuator

We then noted that the 50 ID tooling taper was heavily worn and failed our incoming air gauge testing.  During the rest of the disassembly, we found that the front shaft nut and middle housing nut were difficult to remove and were damaged.  Lastly, the drive dogs were worn and would need to be repaired.  We then moved on to the critical dimension evaluations where quite a few deviations were noted.

Spindle disassembled ready for evaluation

We discovered three deviations that will be addressed during the repair.  First, the middle bearing housing was egged.  Second, both front and rear bearing shoulders had high runout.  Lastly, the rear bearing housing was out of ISO.

SOLUTION

The following actions were performed on this Kessler 000.625.138 spindle:

• Clean, inspect overall dimensions
• Replace bearings, bolts, o-rings, and bellevilles
• Kiss grind the front and rear bearing shoulders
• Grind, plate, grind (GPG) the 50 ID taper
• GPG the middle bearing housing
• GPG the rear bearing housing
• Weld and repair damage to both nuts and drive dogs

RESULT

After reassembly of all components and adjusting bearing preload, we put the spindle through a rigorous break-in and testing procedure to make sure it passes our final quality inspection. See below for the passing test reports:

Front Bearings Vibration Analysis Spectrum:                 Rear Bearings Vibration Analysis Spectrum:

Motor Analyzer Summary:

This spindle passed our final quality inspection and was returned to our customer with a 1-year warranty.