Archive for the ‘Mori Seiki’ Category

Mori Seiki NH 5000 Spindle Repair

Friday, July 27th, 2012

At High Speed Technologies, Inc. we repair Mori Seiki NH 5000 Spindles to original factory condition. Our repairs come with a one year warranty.

This spindle was sent to us because the front bearings were damaged from contamination. Our comprehensive evaluation showed that the spindle had excessive run out at the taper ID. The contact area on the taper was damaged and tool contact was well below acceptable limits.


Mori Seiki NH 5000 Spindle ready to ship

As we dismantled the spindle we found that contamination had migrated past the front seal and migrated into bearings #1 and # 2. This link speaks to some of the problems associated with high speed spindle seals.


# 2 Bearing badly contaminated

Mori Seiki uses a special quad set of bearings with tolerances specific to this model spindle; so not just any bearings will work.

The taper ID was damaged bad enough to require our GPG process to restore it. This machine had a Big Plus taper. HST is a certified Big Plus repair house. To comply with Big Plus specifications HST must grind to extraordinarily tight tolerances.

We always ship the Mazak NH series spindles with a new Super Precision rear roller bearing. With this series spindles the rear roller must be installed on-site by a qualified technician.

If you have a problem with a Mori Seiki spindle contact us. We’re experts on Mori Seiki spindle repairs.

Mori NH 5000 parts cleaned and ready
for inspection.		 Mori Seiki NH 5000 Big Plus
Taper.		 HST is Big Plus Certified.

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Mori Seiki NH 4000 Spindle Repair

Friday, July 27th, 2012

At High Speed Technologies, Inc. we repair Mori Seiki NH 4000 Spindles to original factory condition. Our repairs come with a one year warranty.


Mori Seiki NH 4000 Spindle.

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.


Thick Residual Grease Not Recommended

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.


Multiple Tracks.

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.


Taper Ground Below Gage.

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.

Mori Seiki spindles are very fast. Because of their high speed the Mori engineers use oil mist jets that deliver the correct amount of lubricant directly to the bearings. To achieve this, all of the minute orifices and passages must be carefully cleaned and properly installed. At HST we’re experts at repairing Mori Seiki spindles.

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