Hitachi Seiki VS50 Spindle Repair

The Hitachi Seiki VS50 is a high production CNC vertical machining center.  It can come fitted with this grease lubricated and stator driven spindle that is capable of running up to 12,000 rpm.

CHALLENGE

Our customer stated they were having issues with noise and vibration during operation.  When this Hitachi Seiki VS50 spindle arrived at Northland Tool and Electronics, the first thing we noted was that the spindle was very hard to turn by hand incoming.  After fully disassembly and evaluation, it was noted that there was a catastrophic failure of the #1 and #2 bearings.  We tested the field of the motor and determined that one leg may be beginning to fail.  Coolant was also found to be present in the field.  Lastly, the ID tooling taper had high runout of 8µ and ther was poor tool contact.  No other dimensional deviations were noted for this repair.

SOLUTION

The following actions were performed on this Hitachi Seiki VS50 spindle:

• Clean, inspect overall dimensions
• Rewind the field
• Grind, chrome plate, and finish grind the ID tooling taper
• Replace bearings, o-rings, and assembly screws
• Replace wiper, gripper balls, and seals

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.