Kessler DMS 100.46.4.FDS – H2 Spindle Repair

Our aerospace customer sent us this Kessler DMS 100.46.4.FDS – H2 spindle from a Hermle milling machine after separating it from the drive motor and removing the drawbar. This is often the case when the customer has access to a spare spindle. We were asked to evaluate the spindle on our test stand prior to disassembly to determine if breakdown and quoting were needed. The spindle bearings made a high pitched whine under power and the vibration signature included noise in the ultra-high frequency band indicating a bearing element defect.

CHALLENGE

The exterior of the spindle housing was covered in coolant residue and corrosion.  Upon breakdown we found that the interior components, including the bearings, were also contaminated with the residue. Fortunately for our customer, the drive splines were in good condition and our dimensional evaluation did not show any significant deviation from tolerance in the shaft or housing.

SOLUTION

The following actions were performed on this Kessler DMS 100.46.4.FDS – H2 spindle:

• Clean all parts of the spindle
• Replace all bolts, o-rings, and bellevilles
• Replace bearings

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.