Voumard VMX-120 Spindle Repair
Voumard VMX 120, 120,000 RPM, air/oil mist lubrication, stator drive
Our inspection of this high speed grinding spindle showed catastrophic failure of the front bearing pair. The cage of the #1 bearing had disintegrated completely, contaminating most of the interior with blackened grit. The nose of the spindle shaft was bent from an obvious crash and was blue from heat as far back as the rotor. The bent shaft nose had rubbed out on the front housing cover, and both the inner & outer front bearing spacers were also blue and had rubout damage. We also noted that the shaft balance weights had been damaged by a previous attempt to modify them with a grinder of some type.
Because the spindle shaft was so severely damaged, we machined a new shaft in-house and had it heat treated. We then precision ground the bearing journals & tooling pilot on one of our Kellenberger grinders. Finally we installed the rotor on the assembly as well as new balance weights which we also machined in-house. The newly-built shaft assembly was then component balanced on our Schenk balancer. We reassembled the spindle with new pairs of high speed ceramic bearings in the front & rear, using new front bearing spacers also made in our shop. The final step during run-in of the rebuilt spindle was to trim balance as a system to assure flawless high speed operation.