Mori Seiki SH-403 Spindle Repair

The Mori Seiki SH-403 is a CNC horizontal machining center with a built in pallet changer.  It comes fitted with an oil mist lubricated and stator driven spindle capable of running up to 12,000 rpm.

CHALLENGE

When this Mori Seiki SH-403 spindle arrived at our facility we completed a full breakdown and evaluation.  Upon inspection, we noted that the spindle shaft had heavy damage to the taper, it was cracked at one of the coolant plunger holes.  The bearings failed from coolant contamination, bearings and oil drains were full of coolant sludge. Our customer supplied the tail bearing and ferrule fittings for our rebuild, but the spindle came in without the drawbar assembly, or the shaft splash ring.  We also noted that the drive dogs and front coolant pluger balls were worn out and needed to be replaced.  Lastly, the taper coolant plunger assemblies were also worn out.  No other dimensional deviations were noted for this spindle.

SOLUTION

The following actions were performed on this Mori Seiki SH-403 spindle:

• Clean, inspect overall dimensions
• Replace bearings, oil lines, and o-rings
• Weld, and machine the cracked taper
• Grind, chrome plate, and finish grind the taper
• Rework worn drive dogs
• Replace front cover coolant plunger balls
• Replace taper coolant plunger assemblies

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.