Ping:Anthony


Anthony,
Have you had any problems wuth the rear spindle bearings on your
SQT-18??
Or anyone else in this forum that has an integrated spindle on a
Mazak.
Thanks
Daveb
Reply to
Anonymous
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(DaveB) wrote in news: snipped-for-privacy@news.dslextreme.com:
We have Squirt 15's, 250's and 200's, all with integral spindles, but have never had an issue with the rear bearings (save one of our own doing), always the front. 99% of the time, the cause of the front bearing failure was coolant / contaminent penetration, and this was mainly due to our spindle nose tooling and process. The nose tooling on these particular machines is smaller than the spindle / spindle nose outer ring diameter, thus the crack between the ring and spindle is exposed to any coolant directed at it. The next machine in the line, which has spindle nose fixturing larger than the spindle/spindle nose ring mating diameter, we have never lost a spindle due to even remotely sudden bearing failure, we have just simply worn a few out [excessive end play, spindles were about 8 years old]. As a fix, we installed purge air on the front cover, redirected coolant where we could and do the drain hole PM once every month, haven't lost a spindle to contamination since. Now the motors usually go bad before the bearings wear out.
The one rear bearing we lost, was due to the additional chiller we have on our machines (venturi cooling over the bearings), if you have this, check your air flow, if it gets turned up, it will freeze the bearings, cause ice build-up, which causes rolling element skidding and eventually, bearing failure.
We have also lost one or two that were attributed to the tail thrust becoming WAY excessive [that would take another chapter to explain, so I will just leave it at that - and no...I didn't do it]. (well>2500lbs of thrust)
I would most certianly be talking to Mazak or your spindle rebuilder about the cause of the failures when they disassemble them.
One other thing to check is that your thru-spindle drain system is not clogged, and that the (even though I can't see how it could, still might be possible) coolant isn't running into the bearings out the rear of the spindle.
Reply to
Anthony

Thanks for the reply, out of over 20 Mazaks this is the first.
Regards Daveb
Reply to
Anonymous
(DaveB) wrote in news: snipped-for-privacy@news.dslextreme.com:
If it's a Squirt 18, that means it's several years old, if this is the first, I wouldn't be too awfully concerned about it at this time.
Take note that our machines get *used* and I emphasize *used*, as such, our failure frequencies should show up as anomalies in a nomal distribution plot. We have too many Mazaks for me to keep track of now.
I can give you these pointers... Somewhere around 10 to 13 million cycles, the rails and trucks will need replaced. You may as well do all of them at once. Ballscrews will typically last 2-4 million cycles, we have had them go as long as 6, but this is a rarity and probably more to do with what the process could stand as to actual wear. Probably looking at 3-6 million on spindle motors, (I don't have any info here so that's a WAG based on [my failing] recollection.) Power supplies seem to be a random event, but is somewhat frequent, once every couple of years or so. Drives are about the same. Axis motors...rare event, but it does happen (Z is a *pain in the @ss*) to change. Watch for the thrust bearing on Z to back off on rare occasions. Normally this only occurs after the ballscrew has been changed once. It will act like it has a mile of backlash, when there is absolutely nothing wrong with the screw.
Keyboards (front panels) do go bad, especially after the softkeys get worn through. The pushbutton switches on the panels are fairly cheap made and fail occasionally (cycle start, feed hold, etc) on that note...given our infrequent use of these due to automation, they may be a problematic spot for a shop that has an operator pushing it every cycle.
BTW, are you going to change the spindle, or is Mazak service going to do it?
Reply to
Anthony
I dunno.....what you think?
Daveb
Reply to
Anonymous
(DaveB) wrote in news: snipped-for-privacy@news.dslextreme.com:
The pain is getting it shimmed back up (aligned) correctly. AND the fact you have to take all the sheet metal off of the thing. If it is as old as i'm thinking, it probably has the angled spindle cradle. Make sure you follow the recommened start-up/run-in procedure.
Reply to
Anthony

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