Matsuura MC-1500V4 Spindle Repair



CHALLENGE

Contamination, rear bearing failure & component wear Matsuura MC-1500V4, 3500 RPM, permanent grease bearing lubrication, gear driven This spindle has an unusual bearing complement for a vertical machining center, including a tapered roller bearing and an angular contact pair in the front, with an angular contact support pair on the tail. The rear pair had been removed from the spindle shaft prior to arrival at our facility and had obviously suffered catastrophic failure. The cages which normally contain the rolling elements were broken & there was evidence of extremely high temperatures. Upon disassembly, it was evident that the interior of the front bearing housing as well as the interior of the shaft where the drawbar is located were thoroughly contaminated with coolant. The OD of the spindle shaft behind the front housing also showed signs of contamination and light corrosion. The grease in the front roller bearing was severely degraded from coolant contamination. We observed wear and damage on several other components which ranged from slight to significant. The BT-45 tooling taper ID had several wear bands resulting in poor tool contact and excessive runout measurements. The gripper ball sleeve was damaged and the gripper balls were heavily worn. The ID of the seal collar at the rear of the front housing had light rubout damage.  

SOLUTION

We reworked the rubout damage on the seal collar and corrected the BT-45 taper ID issues with a one-step precision kiss grind. We reassembled the spindle with all new bearings, Belleville springs, o-rings & assembly screws, and installed a brand new gripper assembly which corrected all of the wear and damage issues we had observed. We asked our customer to send us two spindle parts which they did not initially provide with the spindle. We needed the front housing cover & front spacer which are necessary to set bearing capture & to test run this spindle. We set the proper bearing preload & test ran the spindle for ten hours to break in the new bearing grease while recording the thermal & vibration characteristics. Our final outgoing dimensional QC indicated (among other things) tooling taper runout of less than 2µ. Assuming similar operating conditions in our customer’s machine, this 25+ year-old spindle should function like new for many years.

DETAILED CAUSE OF FAILURE

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