Doosan DHP 4000 Spindle Repair

The Doosan DHP 4000 is a large CNC horizontal machining center with a built in pallet changing system.  It can come fitted with this grease lubricated and stator driven spindle capable of running up to 14,000 rpm.

CHALLENGE

This Doosan DHP 4000 spindle was sent in for a complete disassembly and evaluation.  After a close inspection we noted that the spindle nose exhibited evidence of a possible crash (smeared metal).  The #1 front bearing suffered a catastrophic failure, the outer race was broken.  We also found evidence of coolant sludge at the rear of the spindle indicating that the rotary union may have failed.  Critical dimensions were then measured and we found that the Big-Plus tooling taper ID had contact damage and was below gauge line (tool contacts face before taper.)  Lastly, the gripper fingers had significant wear on critical retention surfaces.  No other dimensional deviations were noted for this repair.

SOLUTION

The following actions were performed on this Doosan DHP 4000 spindle:

• Clean, inspect overall dimensions
• Grind, chrome plate, and finish grind the Big-Plus tooling taper ID and face
• Replace Cronidur front bearing quad set and high speed rear roller bearing
• Replace bellevilles, grippers, complete rotary union assembly
• Replace wear rings, seals, 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.