At High Speed Technologies, Inc., we have decades of experience repairing Mori Seiki NH 4000 spindles to original factory condition. Our repairs come with a full year warranty.
This spindle was sent to us because of a drawbar malfunction and when we turned it by hand there were definite indication of bearing damage.
During our initial inspection it became apparent that the spindle had been recently repaired by another shop. This was evident by the fact that there was still heavy residual grease in the bearings. (NH 4000 spindles are oil lubricated) The Mori Seiki NH 4000 spindle is very fast, 14000 RPMs. Only a very thin film of grease should be applied during assembly if any. Grease can saturate with oil causing heat buildup. HST does not use grease with oil lubricated bearings and we do not recommend its’ use.
As we went through the spindle we found some other issues with the drawbar. The front bearings had Brinelling indicating a crash at some point. The balls displayed multiple track lines suggestive of unloading that is often a sign of insufficient preload.
With the Mori Seiki NH series spindles the rear housing stays with the machine. This requires that the rear roller is installed by a qualified service technician. We always provide the correct ABEC 7 Super Precision roller bearing along with the repair.