VTC 16 spindle issues

We have a vtc 16 with a fusion controller, and it seems we are always replacing spindles in the machine. we have had everything inspected and alligned the last time the spindle was replaced, and it looks like it is gone again. We have 4 vtc's and this is the only one that has this problem, I thought it may of been runing the spindle at max rpm for long periods of time, so we had the max rpm lowered from 8000, to 7000, this didnt seem to help. did anyone else have a problem like this, or any ideas of what may be causing this? we have replaced about 5 spindles in the last 3 years.

Who's rebuilding your spindles? I would really question that. Everybody builds a lemon now and then. Nobody is immune to that. The VTC is a good machine (your others ones attest to that). But after this many spindle changes, I would question two things, .... Bad spindle rebuilds, or another area of the machine is causing the spindles to die. What's actually dying in the spindles? and how does it die? In other words, do the bearings seize?, excessive vibrations?, overheating? ....

Well the last spindle went because the fan seized causing to spindle to overheat, and seize. I know the VTC is a great machine, I think this may be just a lemmon, but is there somthing else besides the fan that can cause this to happen, The spindle load dosn't seem to be over high or anything. can you buy a aftermarket spindle with better lasting bearings or anything that may give us more lifetime. We are buying our spindles directly from mazak, so we think it has to be somthing wrong with the housing or somthing, but it all dials in good

Are you buying new spindles or getting them rebuilt by Mazak? If rebuilt, Mazak doesn't rebuild it themselves. They have a spindle shop(s) that they use to have them rebuilt. Is this machine under warranty? If not, I would consider sourcing the rebuild out to another reputable spindle shop.

There are a lot of things that go into a rebuilt spindle. It's not just a matter of changing bearings. Most places use good bearings. It's the installation that usually gets messed up, like wrong preload, wrong clearances, draw bar not balanced properly anymore (may want that checked as well since its usually not involved with a standard spindle rebuild), bent drawbar, ratcheting gear (if you have a geared head). Another possibility is to have the PLG checked on a scope. I've seen these things cause enough vibrations (due to current fluctuations) to mimic bad spindles. Check the chiller unit and lube pumps for proper function.

Just throwing rocks at the wall here......

your in this deep
have mazak put this one in
and hold them accountable

I wonder what the guys at the spindle rebuild shop at the end of the long bay would say about the spindles being rebuilt in someone elses place.

It's done all the time Walt....

Maybe they should take a look at why someone might feel they have to take their business elsewhere.... and that doesn't just apply to spindles....

Shaun.

Can you describe the arrangement of the spindle and drive? Been some time since I’ve looked at one. Those 16 VTC’s. Do they have a stand alone spindle servo motor, but direct coupled to the top of the spindle, inline, no belts or gears, via flexible coupling. I’m wondering about that alignment, run out on the motor shaft, coupling out of balance etc.

The fan you mention, that’s on the Motor? It shouldn’t have affected the spindle enough to cook the spindle.

Regards Phil.

I don't know a whole lot about the arrangement of the spindle and drive, I am just the programmer for our shop, and Mazak does most of our repair work. I will do some more research on it, and maybe mazak will have some ideas when they come down to replace it.

For the most part, there's nothing wrong with Mazak doing the work, even their own spindles (I got ahead of myself in the above post about the spindle... I rarely use Mazaks spindle shop anymore though...). But if it keeps going out, it sometimes helps to get a different eye on things.

I have rebuilt a number of these spindles with one going down it was put in by an ex helper of mine
he call we to help when he had it about 1/2" from in
and it would not go and was lock up there is a coupler that is between the motor and spindle that rust's to motor shaft it always seems to come down when you pull the spindle but won't go back this over loads bearing cages and cracks them the one that went bad on us ran 400 hrs before coming apart
sorry new to this running out of room will start new message

now I pull the coupler with the spindle and clean it and the motor shaft don't take shaft size down just rust off if spindle is very hard to pull off motor
replace bearings in motor also there is an air seal at the base of the spindle there must be air flow at all times even when machine is off this keeps water from being sucked into the bearings as the spindle cools off

note: There are two types bearings one has cramic cage and the other bakealite cage (plastic) the plastic is rated to 15k and will take more shock load and rough handling they cost 700 per set (2 sets in one spindle)

Car.

Thanks. That kinda confirms the motor is directly inline with the Motor. Where’s Whipping Boy when you need Him? Should we say Shubin rings once more? Sound’s very typical of a Mazak style shaft to shaft coupling.

Your problem with inserting the spindle up into the coupling probably wasn’t so much to do with the rust. (Although it shouldn’t have been there), its because your pushing into the lock ring, the way they are compressed to bite the shaft. Much better to drop them right off, and bring them up into the coupling hub, after the spindle housing is at the correct height. I’m not sure about that ceramic cage thing.

Your little problem, with posting. You just have to scroll down in the little box, provided for replying. Or just keep typing, it will move down automatically. The size of the box, isn’t the limit, to what you can type here. Or write your stuff in a word processor program like word, or note pad, then cut & paste the whole shebang into that reply box. Regardless, Welcome aboard.

Shaun.
I’d be betting a bottle of Kentucky’s finest, that your problem, is to do with alignment of the motor to spindle. 1 machine out of 4 chewing spindles. The spindle keeps getting replaced, but the motor and coupling sit in place, never being touched.

Those couplings have 6 tensioning screws to lock them. Unless they are torque’d up in order. You can pull a big deflection resulting in run-out of the coupling. You need to have checked, the runout of the coupling, prior to installing the spindle. The motor registration journal also needs to be checked for run-out. You would need to lift the motor for this, to dial off the spindle into the motor location journal.

Regards. Phil.

well in a way I kind of hope that thing gives out soon, it is just hanging on by the skin of its teeth (sounds like the wife before her coffee) I think you may be on to somthing there, I know the motor has never been replaced, this very well could be the problem, is that somthing we can dial or somthing to check the alignment, or should we just pull it off and clean all the rust and realign it

I was wondering if anyone could reccomend a place other then mazak that rebuilds spindles? and if they will just sell you a rebuilt spindle, or do you have to wait for the spindle to be rebuilt? just thinking about down time, and is there any companies in canada that specialize in machine maintence, or is replacing a spindle somthing that should be done by a mazak tech?

i'm way out of date on mazak mills
(last mazak mill spindle i had out was an m2 vintage with a 2 speed gear box nothing like what we are describing here)
but cars story sounds very good
as far as someone that can exchange a mazak spindle with your core your gonna have to google that stuff.
replacing spindle cartradges is pretty straight forward.
but as car states you can have trouble with them just like trying to set up your own bearings preload and all
i guess i have to go back to... after spending 5k for a spindle unit another grand for installation is money well spent if your not sure about how to do it