Toshiba BMC 630 Failure from lack of bearing lubrication
Toshiba BMC 630, 5,000 RPM, oil mist lubrication, gear driven
This horizontal milling spindle had failed from insufficient lubrication of the bearings. When we informed our customer of this, we advised them to thoroughly inspect the operation of their lubricator. We also noted several dimensional issues: high runout & poor tool contact in the taper, worn drive dogs & grippers, 150mm front housing bore out of round where the roller & pair of angular contact bearings are located, and scoring of the drawbar shaft from the action of the Belleville springs, as well a severe bend & wear at the rear of the shaft where the rotary union is attached.
We performed a precision grind, chrome plate & finish grind of the 150mm front housing bore, as well as a kiss grind of the tooling taper. We also reworked the drive dogs to repair the existing damage. When all components had been thoroughly cleaned, we reassembled the spindle with new bearings, Bellevilles, grippers, oil lines, ferrules, o-rings and assembly screws. Our final QC process included run up of the spindle with vibration & thermal analysis over a six hour period.