spindle cooler necesarry

Hey guys,

I recently (well actually quite a while ago, but only just got it running) bought a Hartford hv35 vmc.

I got the manuals for the machine after running new air lines (they were all cracked) as i noticed 3 hydraulic lines not connected to anything - 2 of them are for the spindle chiller. I called the PO of the machine and he never had a chiller on it that he can recall (only hobby use by him basically).

So my question is... is it necesarry? it's got an 8krpm spindle (belt drive from motor to spindle assembly, not sure what the reduction is, haven't checked) and i plan on using it at or near that 8krpm fairly regularly (this will mostly be running aluminium as my mazak vqc20/40 is just too slow)

I'm currently running some continuous running tests on it to see how the temps go and so far after 45 mins of running (first 15 at 4krpm, then 6krpm - then 8krpm) the hottest part on the spindle housing is only ~10.5*c over ambient, while my vqc (that has been running for about 8 hours straight at this point, mostly at its 4krpm max) shows a hottest point at ~14*c over ambient (all the covers are on so I could possibly get a higher reading at a different spot with the covers off)

I was thinking of maybe just putting a basic pump/res setup on it to circulate some oil through it in case it's the lubrication oil as well in the spindle, which will also in turn work as a rudimentary cooler (just be the higher volume of oil - unless the pump produces more heat therefore negating the advantage... not sure on that)

Cheers,
Trav

If the machine is designed to have one, and you intend to use it at max rpm for extended durations, then I'd say the answer is yes, you need it.

One of mine, an old Hurco with only a 6K max, 40 taper spindle, the spindle chiller was out of commission for a while due to a failed pump, I wasn't doing any precision work on it at the time so didn't pay attention to that aspect, but I did notice that tools that had been running high rpm for any duration required much more force to eject from the spindle. During a tool change they would release with a very audible "pop" that did not ever happen with the chiller working.

On the plus side, it really shouldn't be hard to pick one up. Even if you can't find a used one kicking around somewhere a new Habor from Taiwan is probably not expensive.

gregormarwick said:

If the machine is designed to have one, and you intend to use it at max rpm for extended durations, then I'd say the answer is yes, you need it.

One of mine, an old Hurco with only a 6K max, 40 taper spindle, the spindle chiller was out of commission for a while due to a failed pump, I wasn't doing any precision work on it at the time so didn't pay attention to that aspect, but I did notice that tools that had been running high rpm for any duration required much more force to eject from the spindle. During a tool change they would release with a very audible "pop" that did not ever happen with the chiller working.

On the plus side, it really shouldn't be hard to pick one up. Even if you can't find a used one kicking around somewhere a new Habor from Taiwan is probably not expensive.

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I haven't found any around second hand anywhere near me and new ones appear to cost around the 4k aud mark, which is too expensive considering I paid $2k for the machine is self

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Hi Trav.

Purpose of the chiller isn't to protect the spindle / and or grease @8k, its to do with thermal growth of the machine structure. Try your test again first thing in the morning, by zeroing an indicator on the head stock in the Y axis direction directly in front of the operating position. Then run your 4 - 6 -8K rpm trial.

The Z axis head stock assembly absorbs that heat energy, and grows directly off the Z axis column. Moving the spindle axis towards you and changing the Y axis position. In bad cases you don't even need a 2 micron clock. You can see it with a half thou / 0.01mm clock.

Worst on I ever saw, was a cast head stock were they either got the casting or machining wrong. The upper tier of the spindle bore was higher than the top of the spindle. So when it was stopped it oozed gear oil into the grease filled spindle, via the top labyrinth seal.

So it was chock a block full of Klubber / Gear Oil butter, which churned and pumped out heat. That would grow 7 thou directly towards you.

In my travels down under, I've never seen a used Oil Chiller for sale. You might get lucky if you search scrap machines.

The few chillers I've had to replace. Would you believe agents for Daikin, claim 7 - 8$K for shit they don't have ex-stock / import only.

I've had good luck with Habor via Global Machine Parts

Regards Phil.

machtool said:

Hi Trav.

Purpose of the chiller isn't to protect the spindle / and or grease @8k, its to do with thermal growth of the machine structure. Try your test again first thing in the morning, by zeroing an indicator on the head stock in the Y axis direction directly in front of the operating position. Then run your 4 - 6 -8K rpm trial.

The Z axis head stock assembly absorbs that heat energy, and grows directly off the Z axis column. Moving the spindle axis towards you and changing the Y axis position. In bad cases you don't even need a 2 micron clock. You can see it with a half thou / 0.01mm clock.

Worst on I ever saw, was a cast head stock were they either got the casting or machining wrong. The upper tier of the spindle bore was higher than the top of the spindle. So when it was stopped it oozed gear oil into the grease filled spindle, via the top labyrinth seal.

So it was chock a block full of Klubber / Gear Oil butter, which churned and pumped out heat. That would grow 7 thou directly towards you.

In my travels down under, I've never seen a used Oil Chiller for sale. You might get lucky if you search scrap machines.

The few chillers I've had to replace. Would you believe agents for Daikin, claim 7 - 8$K for shit they don't have ex-stock / import only.

I've had good luck with Habor via Global Machine Parts

Regards Phil.

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I'll give that a crack in the morning. Hadn't thought of that issue. I'll give it a test tomorrow.

So the issue is more of a heat soak (throughout the whole head casting) than an actual heat issue?

Seeing as it's not a lubrication function would some form of water-cooling work or would the much lower viscosity not play nice with the seals? I ask only because water chillers are a lot more common.

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There not exactly hard to knock up, a small oil cooler and fan, a small electric motor and small hydrulic pump and a tank + a few bits of hose and your done. Most the bits can be cheaply sourced second hand and your not going to need much cooling power to stop a spindle getting hot!

adama said:

There not exactly hard to knock up, a small oil cooler and fan, a small electric motor and small hydrulic pump and a tank + a few bits of hose and your done. Most the bits can be cheaply sourced second hand and your not going to need much cooling power to stop a spindle getting hot!

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I guess question number 2 is how much cooling do I need?

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Look on HGR website. Prob grab a chiller for a few hundred bucks.

The RPMs your talking about would be fine without a chiller. Rather then guess, run the spindle at 8k for the entire day and see how warm it gets. My guess is not much.

Ill add a note of caution here, for what its worth.

I purchased a used fadal not long ago. After installation,couple of test cuts, and checking everything over, I let it go for an 18 hour run @8500
When I came back next day, the chiller pump had failed. My assumption is that it also cause the spindle bearings to crap out as well.
Might have been the spindle was on borrowed time, but sounded just fine initially (I had a second machine directly beside with a brand new spindle to compare).

Now I have 2 new spindles inside 200 square feet.

SteveEx30 said:

Look on HGR website. Prob grab a chiller for a few hundred bucks.

The RPMs your talking about would be fine without a chiller. Rather then guess, run the spindle at 8k for the entire day and see how warm it gets. My guess is not much.

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i live in Australia, so the shipping would be exorbitant on something like that, and i'd have no way of knowing it's condition.

barbter said:

There are two types of spindle chillers.
1 type that is absolute temperature controlled and the other that tracks actual air (factory) temp and lowers by say 5 degrees (if that's what the dial is set to).
I had a Leadwell with an absolute one, where the dial was always set to 15 (by memory).
Tech came in one day and I didn't know but he changed the dial to 5 (because the other machines were all set to 5 ).
The guy running the machine didn't say anything and two days later the spindle seized.
He called me and I immediately noticed condensation all over the spindle nose and holder and it was freezing cold to touch.
He then said to me that he'd noticed it last night and thought it was odd (Grrrr, never have a business partner!).
Anyway, spindle repair company said that water ingress was in the bearings and the grease was flushed out, so I guess too much condensation was the cause.
Long and short of it, safest way is to contact the manufacturer and ask what they specced!

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It was a massive uphill battle getting manuals for the machine, as the local agent dont have records back that far and the manufacturere didn't either (i guess that's the downfall of not buying high end, like mazak, where they have full records of everything and support everything.)

macds said:

Ill add a note of caution here, for what its worth.

I purchased a used fadal not long ago. After installation,couple of test cuts, and checking everything over, I let it go for an 18 hour run @8500
When I came back next day, the chiller pump had failed. My assumption is that it also cause the spindle bearings to crap out as well.
Might have been the spindle was on borrowed time, but sounded just fine initially (I had a second machine directly beside with a brand new spindle to compare).

Now I have 2 new spindles inside 200 square feet.

Click to expand...

I guess that's part of the risk of buying second hand though. With what i paid for this machine, it doesn't need to do a lot of work to pay it's self off, so hopefully it can at least achieve that :P

thermal expansion test

so i tested the thermal expansion (15min at 4k then 1 hour at 8k) and i measured ~.02mm of growth away from the column, which i'm entirely happy to just deal with. most of the work this machine will be doing is 3d milling of aluminium, for parts that are mostly cosmetic, and i'm happy to just be more careful with tighter tolerance parts.

So if there's nothing else that an oil chiller is going to achieve for me, apart from limiting that thermal expansion and limiting the temp of the spindle, I'm happy with that result as far as usability is concerned.

If there is something else i am missing please let me know.

xa-mont said:

I guess question number 2 is how much cooling do I need?

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My best seat of the pants guess would be well under 10% of spindle power, probably more likely between 3-5% on a belt driven spindle. Really not much at all in the scheme of things.

Now a gear driven spindle and gear box combined, yeah your easily in the 10-25% of input power range depending on ratios and oils etc. Splash lubed gear boxes especially in smaller power levels can take a large % of the drive power. Tend to be more efficient as power increases. But a small engine lathe say 2-3hp motor and your easily probably losing a 1/2Hp plus to spin the spindle at full speed.

IMHO key thing to realize no one cares what you paid for the machine, the spindle bearings will still cost just the same to replace as wehn the machine was far newer! Equally things like spindle bearings are just one of the items your going to realistically expect to replace in the life of a machine tool, just like tires on a car, hence it kinda pays to budget accordingly.

adama said:

My best seat of the pants guess would be well under 10% of spindle power, probably more likely between 3-5% on a belt driven spindle. Really not much at all in the scheme of things.

Now a gear driven spindle and gear box combined, yeah your easily in the 10-25% of input power range depending on ratios and oils etc. Splash lubed gear boxes especially in smaller power levels can take a large % of the drive power. Tend to be more efficient as power increases. But a small engine lathe say 2-3hp motor and your easily probably losing a 1/2Hp plus to spin the spindle at full speed.

IMHO key thing to realize no one cares what you paid for the machine, the spindle bearings will still cost just the same to replace as wehn the machine was far newer! Equally things like spindle bearings are just one of the items your going to realistically expect to replace in the life of a machine tool, just like tires on a car, hence it kinda pays to budget accordingly.

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The reason I mention that I paid very little is that it's somewhat of a throw away machine. If the spindle bearings were to shit the bed, is be almost certainly scraping the machine.

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