Mazak MTV-414/32 Spindle Repair

The Mazak MTV-414/32 is an older CNC veritcal machining center.  It comes fitted with a grease lubricated and belt driven spindle capable of running up to 10,000 rpm.

CHALLENGE

This Mazak MTV-414/32 spindle was seized incoming due to contamination of rust throughout.  After disassembly and evaluation, we noted that the bearings and spacers were contaminated with rust and the bearings were washed out and packed with particulate contamination.  The grippers were worn and the alignment pin was stuck in the shaft.  We then measured the critical dimensions (bearing journals, housing, taper, etc.) and found a few deviations.  First, the taper ID was slightly bell mouthed and had 18/20µ of runout. Second, the front journal had 4/5µ of runout.  Lastly, the housings were oversized and worn.   It was also noted that the drawbar had homemade spacer and was scored from the bellevilles.

SOLUTION

The following actions were performed on this Mazak MTV-414/32 spindle:

• Clean, inspect overall dimensions
• Drill out and replace alignment pin from shaft
• Grind, chrome plate, and finish grind (GPG) the drawbar OD
• GPG the ID taper
• GPG the front journal
• GPG the front and rear housing bores to ISO tolerance
• Replace bearings, bellevilles, roll pin, o-rings, and assembly screws
• OEM grippers must be supplied by the customer

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.