The Bridgeport Torq-Cut 22 is a smaller CNC vertical machining center. It comes fitted with a grease lubricated and belt driven spindle capable of running up to 7,500 rpm.
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Mitsubishi Large Mill Spindle Repair
Mitsubishi machine tool referred an aerospace customer to us. The customer had sent the large milling spindle to one of our competitors and the spindle failed shortly after installation. Our spindle repair competitor refused to cover the spindle under warranty even though the spindle failed within days of the installation.
CHALLENGE
When the spindle arrived we were tasked with finding the cause of failure. Here is what we found: The front shaft journal was egg shaped and badly scored causing stress to the bearing. The damage to the shaft and housing were indicative of extremely poor bearing installation practices. The bearing spacers were scored during the installation causing a non-parallel condition which leads to premature bearing failure. This spindle had a hydraulic rotor. It was also installed improperly causing scoring to the shaft and rotor and bending the shaft. The rear cover was in contact with the rear nut causing metal debris to enter the bearings. The bearings were not installed in the proper orientation causing a lack of lubrication to the front quad set of bearings.
SOLUTION
The following actions were performed on this Mitsubishi Large Mill spindle:
- Clean all parts of the spindle
- Replace bearings, o-rings, and assembly screws
- Grind, chrome plate, and finish grind (GPG) the front shaft journal
- GPG the shaft where the hydraulic rotor sits
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.
DETAILED CAUSE OF FAILURE
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More Case Studies
Repair History - Here are examples of similar spindle repairs that may contain additional information that will help you. If you have additional questions, please contact us.
OD grinding — or outside diameter grinding — is a cornerstone of precision manufacturing, where exact specifications and flawless surface finishes are essential.
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