Thread: Is there benefit to warming up a spindle that doesn't run warm?

We warm up all our machines, every morning. I know on the lathes, they do get hot enough during the day to grow half a thou or more, I plan on it and adjust through out the day. Our newer machines with coolant chillers hold temp a lot better, but they need time to stabilize. On the VMC's I believe the warm up is intended to stabilize the spindle at operating temperature to make sure the bearings and oil are at operating temperature so they have as little wear as possible, not to hold size. In particular, our Kitamura high speed will not go over 1k RPM without warming it up, and they specifically say that it is to keep the spindle oil from settling. I believe the Haas gives a warning if it has not been run in a couple of days to the effect of the spindle may be damaged by running at high speeds without warming it up first. So my impression is, warm up the axis to get the machine to temp and lube the ways, warm up the spindle to prolong its life.

I guess it is quite machine dependent. The concerns expressed don't seem to apply to my machine, and (I rechecked) it is not mentioned in the manual. Sounds like if you have an oil lubricated spindle, or box ways that heat with use, or motor encoder positioning with no temperature compensation, then an extended warm up makes sense and accomplishes something. Sounds like no benefit on my machine though.

I have a router table with a 3HP 24000 RPM Colombo spindle they require a 10 minute warm up for the ceramic bearings. They want the spindle at 80* before running it. I have check the spindle temp and it never gets that hot without load I usually run it for 5 minutes at 9000 RPM then 5 more minutes at 18000 RPM. It has a spindle fan that is on all the time the spindle is powered up I have thought about turning the fan off but I am afraid it might get forgotten to be turned back on.

I feel it cannot hurt to allow the spindle to run a few minutes at a low RPM with no load to get the grease/oil viscous enough to coat the bearings. There is enough to lose by not doing it.

Next step...does anybody besides me like to have the machine to sit idle a few minutes before shutting them down. I like to wait till at least the cabinet fans and spindle motor fans shut down...usually a few minutes longer.

Originally Posted by SIM

I feel it cannot hurt to allow the spindle to run a few minutes at a low RPM with no load to get the grease/oil viscous enough to coat the bearings. There is enough to lose by not doing it.

Next step...does anybody besides me like to have the machine to sit idle a few minutes before shutting them down. I like to wait till at least the cabinet fans and spindle motor fans shut down...usually a few minutes longer.

I do the same especialy on my two Matsuuras with oil coolers. I like to let them run for a few minutes before shutting down.

I also warm up my machine almost everyday for 20-25 min. Its just good insurance IMO. I move the turret or table around while stepping up the rpm over that period of time.

Jason,

I agree with running the spindle for a couple of minutes not under load. But in my case a 30 minute warmup (which does not actually warm anything) is just going to reduce my spindle life, I think. On my roller way machine I don't think moving the table around would have any benefit, though I think moving it to the extremes all directions just once might - it would re-coat the rails with oil, preventing corrosion.

Originally Posted by swarf_rat

I agree with running the spindle for a couple of minutes not under load. But in my case a 30 minute warmup (which does not actually warm anything) is just going to reduce my spindle life, I think. On my roller way machine I don't think moving the table around would have any benefit, though I think moving it to the extremes all directions just once might - it would re-coat the rails with oil, preventing corrosion.

Sounds like you have your machines figured out, I would not sweat it.

Bearing life is the driving factor behind spindle warmup on a mill. For a simple test, show up tomorrow morning and fire up your machine, wing the spindle up to max RPM immediately, and note the spindle load. Leave it running wide open and go have your coffee. Come back 20 minutes later and look at the load again - it will be quite a bit lower. Not sure how important it is on an 8K spindle, but on a 12K+ spindle, the bearings won't last very long without a proper warmup cycle.

Originally Posted by swarf_rat

I guess it is quite machine dependent. The concerns expressed don't seem to apply to my machine, and (I rechecked) it is not mentioned in the manual. Sounds like if you have an oil lubricated spindle, or box ways that heat with use, or motor encoder positioning with no temperature compensation, then an extended warm up makes sense and accomplishes something. Sounds like no benefit on my machine though.

Yes. It is machine and tolerance dependent.

When company bought the 2 Haas vf3
On my question "For How long can i run the spindle at max load and how long at max RPM ?" (12K machines)
The Application engineer sad "All the time 24/7 if you want to....."
...
...
...
"How long will the spindle/motor live?" asked I after a long pause.
"Won't affect it in any way" he replied.

After that i didn't bother to ask him any questions at all.

I guess we can not really rely too much on what even the manual says.
After all the spindle will survive warranty period anyway no matter whether it was warmed up or not.
What happens after that is a problem that can be fixed with customers $$$

My Matsuura(1987)has 4500 max rpms. I start her @ 35 rpms,make 3 max moves in XYZ, bump rpms and repeat,last command is 1250 rpms(she shifts to high gear here) and run all axis again.
I feel better aboot it,ways are oiled,spindle lubed and brought to life again,for the gazillionth time.
Do you fire your ride and max throttle instantly? not me, 2 miles @20mph(thats how far the pavement is)PLUS,gives me time to find my scale and remember my name...
Gw

The warm up would be to get the oil/grease moving in the spindle bearings. I would do it, just for that reason. Doesn't matter if your spindle runs warm or not. As mentioned by Greg above, you wouldn't get in your vehicle, fire it up and hold the accelerator on the floor, it's just, well, silly.
Dave

FWIW, my Haas VF3 used to have a 'cold spindle'. But, surface finishes were not all that great either. I rebuilt the spindle cartridge, and found out at that time, that the inner preloading collar was loose (not literally, but rather, not applying any preload), so the main bearings were running essentially free of preload. When I replaced the bearings, I noticed after heat shrinking the preload collar, that it still required a 'bump' with the press to get the collar to seat, as its expanded length while hot, would relax the preload as the collar cooled down.

Afterwards, I did get an improved surface finish, and the spindle did gain a bit of heat over time. So a 15 minute warmup at least would be a good idea if attempting to maintain critical offsets from one day to the next. But for a cold spindle, I don't see that it would affect much in the way of part quality.

I have had a lathe and a mill that would throw occasional errors. Sometimes spindle related errors, sometimes other types. For some crazy reason, after "warming up the spindles" (running for a while) it either stopped the errors for the day, or decreased their frequency.

P.S. "A while"= approx. 15 minutes at 25% of the max. spindle speed.

This is the warm up procedure for my 15k, Matsuura HMC. The spindle does get warm after the run in cycle, but its old, and believe it or not its the original spindle (15 year old machine)! I follow the procedure and plan to do so when I do get a new spindle for it. This spindle has an oiler and a spindle chiller. I feel fine running it at 10-15k all day.

Wow, that is quite a regimen for the Matsuura! That is a 4.5 hour warm up if left for a week! Not a good occasional use machine....

Originally Posted by SchneiderMachine

As mentioned by Greg above, you wouldn't get in your vehicle, fire it up and hold the accelerator on the floor, it's just, well, silly.
Dave

An automobile engine runs at several hundred degrees above its resting temp and has mostly sliding surfaces - not quite the same as a spindle bearing?

Originally Posted by Joe788

Bearing life is the driving factor behind spindle warmup on a mill. For a simple test, show up tomorrow morning and fire up your machine, wing the spindle up to max RPM immediately, and note the spindle load. Leave it running wide open and go have your coffee. Come back 20 minutes later and look at the load again - it will be quite a bit lower. Not sure how important it is on an 8K spindle, but on a 12K+ spindle, the bearings won't last very long without a proper warmup cycle.

Now that is an interesting suggestion which I intend to try - I will report back.

I remind everyone of the title of the thread: Is there benefit to warming a spindle that doesn't run warm? If it ran warmer than at rest, then I'm seeing it. But, other that a couple of minutes to redistribute the grease (and I am skeptical on even that), if it does not change temperature while running, then I can't see what good it does.

Those of you do run extensive warm ups: if you use the machine in the morning, then leave it idle until afternoon - say there is a 3-4 hour gap - do you warm it up again? Surely it would be back to its ambient temperature again...

Originally Posted by swarf_rat

I remind everyone of the title of the thread: Is there benefit to warming a spindle that doesn't run warm? If it ran warmer than at rest, then I'm seeing it. But, other that a couple of minutes to redistribute the grease (and I am skeptical on even that), if it does not change temperature while running, then I can't see what good it does.

Those of you do run extensive warm ups: if you use the machine in the morning, then leave it idle until afternoon - say there is a 3-4 hour gap - do you warm it up again? Surely it would be back to its ambient temperature again...

Swarf, we warm up all of our machines, lathe or mill, and move the axis as best we can to put some heat in the screws if so be it. As far as re-warming, we'll do that if we have let the machine sit for a while as most of our warm ups are about 30 minutes max. On a basic VMC warm up we feed the X and Y at 100ipm from home to the opposite corner, and rapid back home, then move Z down about 2/3 of it's travel and then rapid home, loop this about 10 times at each spindle increment, which is in 20% increments of the max spindle speed. Lathes are pretty much the same with independent axis movements instead of combined. Our Mazak horizontal's warm up was written by one of their app engineers and remains in a feed mode throughout, but increases feed rate along with spindle speed up to maximum, but still takes about 30 minutes. I do not want to loose a spindle in that one that I have to eat just from being lazy...probably close to $25k by the time the dust settles for an intregal motor, 40HP, 18k spindle. The Mazak has a timer function to turn the machine on and start the warm up at a preset time if we choose, but we end up not using it as we usually have to unload a tombstone of parts when we first arrive anyway, so that takes close to the same amount of time as the warmup.

BTW, I am pretty sure that the Mean Time Between FAILURES on a spindle is way lower than Mean Time Between CRASHES. I would lump operator error in to the crash catagory too, such as blowing air up into the spindle to clean chips and coolant, but actually blowing the chips and coolant into the bearings. Also, there are some spindle designs that are just a bad design and likely to fail no matter what you do...I know after putting 8 spindles into a machine in a short couple year period (all from coolant migrating into the lower bearings from a poor labrinth seal design.) Needless to say, I'm a bit Spindle-Sensative.


Steve

Alright, I tried this: measured spindle cartridge temp, started machine and within a minute ran it up to 8000 rpm.

At startup, 74 deg F

@2000 rpm, spindle load alternating between 0-1%
@4000 rpm, load between 0-1%
@6000 rpm, load 2%
@8000 rpm, load alternating between 3-4%

Then I went back to 2000, and stepped up in about 10 minute intervals. Measured temp again, this time 77 deg, same inside taper as good as I could shoot it with IR. However, spindle load was the same. Maybe the display spent a little more time on 3 than 4 at 8000. But very little difference. Now of course that was warming the spindle, belt, motor, spindle drive electronics - all of which potentially should be warmed.

Then I ran a program for about another 20 minutes, light cuts mostly at about 5000. Measured temp again, about the same, spindle loads the same.

So unlike my previous test in which the spindle temp dropped, it did rise a bit in this one. Maybe because there was no (during warmup) or very little (running this program) coolant bouncing back on the spindle.

Taking a look at several bearing manufactures catalogs, there is some consensus that spindle bearings should be warmed in 20% steps "up to operating temperature" for maximum life. They suggest waiting at each step for the temperature to stabilize, without suggesting how that might practically be measured. My spindle bearings are hybrids, the ceramic balls have 1/3 the thermal expansion of steel and are said to run cooler and more stable as a result. Also these bearings are spec'd at a "maximum achievable speed" of 19,000 rpm, but only run 8000 in my machine. Maybe that's the reason I don't see much temp rise. But there is a few degrees, so maybe I should be warming it up a bit.

The warmup in the shops I have worked in was religious - and every shop that uses warmup ritual just sort of seems to run better itself, the shop I mean.

When I have worked in shops that do not perform warmup routines, there is a general lack of perfection.

I personally like to run warmup, so I can feel the spindle before I get to work, and if it is too hot, I can report it to the boss before I even put a load on it, and I can listen to the ways without the noise of the tool cutting diguising any telltale clicks and clunks.

Buying used equipment over the years will make you appreciate the little things such as warm ups, even if it is just to get all the lube in the right places.