Cincinnati Sabre 2000 Spindle Repair

The Cincinnati Sabre 2000 is a large CNC vertical machining center.  It comes fitted with an oil mist lubricated and pulley driven spindle capable of running up to 8,000 rpm.

CHALLENGE

This Cincinnati Sabre 2000 spindle had significant endplay when it first arrived at Northland Tool and Electronics.  Upon inspection,  it was found that the spindle bearings failed from heavy contamination with greasy black coolant sludge.  The tooling taper ID was worn and had poor tool contact with excessive runout.  It was also noted that the taper gage sits below gageline.  We then measured and inspected the critical dimensions of the spindle and found a couple of issues.  First, the rear belleville journal of the shaft was heavily worn from the action of the springs.  Second, the 110mm housing bore was worn oversized and egged. The front of the housing was +3/+12µ and the rear was +7/+12µ (ISO is ±7.5µ).  No other dimensional deviations were noted for this repair.

SOLUTION

The following actions were performed on this Cincinnati Sabre 2000 spindle:

• Clean, inspect overall dimensions
• Grind, chrome plate, and finish grind (GPG) the tooling taper ID and rear belleville journal
• GPG the 110mm housing bore
• Replace bearings, bellevilles, gripper balls, lock washer, gasket, o-rings, and assembly screws

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.