Daewoo DMV500S Spindle Repair

The Daewoo DMV500S is a CNC vertical machining center.  It can come fitted with this grease lubricated and pulley driven spindle that is capable of running up to 10,000 rpm.

CHALLENGE

Our customer sent in this Daewoo DMV500S spindle stating that the spindle is noisy and the tool gets hot.  Once the spindle arrived at Northland Tool we completed a full disassembly and evaluation.

This is what we found:

• Spindle was difficult to rotate by hand and the bearings felt very worn
• Coolant got into the front bearings and the #1 bearing catastrophically failed contaminating the others (Pic 1&2)
• The drawbar was extremely difficult to take apart and the tail was damaged during breakdown
• The bellevilles dug into the draw bar shaft
• Front drive dogs were heavily worn and need to be replaced
• The grippers were also heavily worn (Pic 3)
• Rear pulley key was very difficult to remove, the threads in the center were stripped, and the key was damaged
• ID 40 taper had high run out and uneven contact

SOLUTION

The following actions were performed on this Daewoo DMV500S spindle:

• Replace Bolts, O-rings, Bearings, Bellevilles, and Grippers
• Grind-Plate-Grind (GPG) ID 40 Taper due to high run out and uneven contact
• Manufacture new drive dogs, heat treat new drive dogs
• Manufacture new pulley key
• Repair damaged drawbar
• GPG Drawbar OD

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.