Kitamura Mycenter 3XiH Spindle Repair

The Kitamura Mycenter 3XiH is a high speed CNC vertical machining center.  It comes equipped with an oil injection lubricated and gear driven spindle capable of running up to 20,000 rpm.

CHALLENGE

Prior to shipping this high speed vertical machining center spindle to us, our customer indicated that it was very noisy when operated above 12,000 RPM. When we disassembled the spindle, we noticed that the rear shaft nut was only finger tight. Even more telling was the heat discoloration evident on the inner spacers of not just the rear roller bearing, but also between the front quad set of angular contact bearings. This was indicative of improper lubrication which would have eventually led to catastrophic failure of all bearings. Fortunately, this did not occur, and the only dimensional deviation we found in our evaluation was in the tooling taper. Our customer uses both CAT & Big-Plus dual contact tooling, and we found that the Big-Plus tooling was contacting the shaft face before it was touching the taper itself.

SOLUTION

We first performed a grind, chrome plate, and finish grind of the worn tooling taper to Big-Plus specification. We then reassembled the spindle with all new bearings, o-rings, assembly screws & grippers, which we had found to have significant wear.

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.