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Tips/Techniques Coolant for my mill?

Tips/Techniques
PaulL

PaulL

Technologist at Large
Premium Member
Having done Bad Things(tm) to too many end mills I'm thinking it's time to sort out coolant on my First mill.
It has a built-in pump, but it's not running - I need to move it 24" away from the wall and do some debugging in there if I want it to run. The machine is designed to filter/cycle fluid from the sump it seems, which also doesn't seem to have any tidy clean-up facility. I expect the sump to get pretty gross.
I've also been looking at mist coolant systems, which would save me moving the machine. These are so extravagantly cheap that I'm probably going to press the button before I finish this paragr...ok, done, and I'll report on it when it arrives, oh, on Monday. That's too soon, so I'll report on it once the insulation is done in my shop.
And now that I've spent 40$ on a stop-gap, is it worth getting the flood coolant going on the mill? I have no experience with either flood nor mist.
 
I'd be figuring out why your toasting endmills before going that route. What are you using for speeds and feeds data?

Feeding an endmill into the work from the wrong direction (up milling v.s. down milling) can be deadly on endmills. Excessive vibration is another indication that something isn't right.
 
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PaulL said:
And now that I've spent 40$ on a stop-gap, is it worth getting the flood coolant going on the mill? I have no experience with either flood nor mist.
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Me either. But I'm quite happy with dabbling some on with a small brush. I don't want coolant all over my shop.
 
YYCHM said:
I'd be figuring out why your toasting endmills before going that route. What are you using for speeds and feeds data?

Feeding an endmill into the work from the wrong direction (up milling v.s. down milling) can be deadly on endmills. Excessive vibration is another indication that something isn't right.
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Engineer's Black Book drill speed table, mostly. Probably not good enough.
I'm guessing I'm not running the small ones nearly fast enough - 4-5mm I have to force myself to believe the machine won't tear itself apart in the 6000 RPM range that my mill won't even reach.
And this is for 4mm keyways, so I'm going to have to figure something out.
 
You can use the little machine shop calculator

CA61A94D-B8CD-4A2C-8600-AEAD604C3831.webp
 
phaxtris said:
there has gotta be a reason your toasting endmills ? what are you using ? carbide or hss ?
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HSS. Cheap ones in from AliExpress. Even the larger ones have failed quickly.
But I've also burned up a 3/8" mill from KMS, so I'm leaning towards a technique problem.
 
PaulL said:
HSS. Cheap ones in from AliExpress. Even the larger ones have failed quickly.
But I've also burned up a 3/8" mill from KMS, so I'm leaning towards a technique problem.
Click to expand...

The KMS stuff is probably the same as the AliExpress stuff.

What do you mean by burning up?
 
The problem with the speed and feed calculators is they make assumptions about cutting speed.
So I asked google "What grade steel is an electric motor shaft". The answer was SAE1045. So that's what I selected in my Machinist toolbox.
With a 4mm 2 flute end mill for roughing this is what it came up with.

1666066060456.webp

Notice it select 68 FPM for removal rate. That might well be commercial production speeds. The suggested travel speed is 9 IPM at 1649 RPM with a 0.1336" depth of cut.. I'd probably run 5 IPM and plunge about half the axial DOC per pass like 0.075"
 
YYCHM said:
The KMS stuff is probably the same as the AliExpress stuff.

What do you mean by burning up?
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The four points "disappear" leaving me with a poor-man's ball-end, and I see oxidation colours a short distance up the shaft.
Looking at @jcdammeyer's feed chart, I realize I'm probably taking too deep a cut with these tiny end mills. That will be my next test.
 
@PaulL You mentioned 4 points. Four flute cutters aren't really good for plunge cutting (normally). But I redid the table with a 4 flute end mill.

1666068722655.webp

Notice the load per flute doesn't change but because there are 4 of them they now suggest 15 IPM but RPM has dropped a tad. I'd still stay with 1600 RPM or so but stay with the other DOC and slower IPM.
 
PaulL said:
The four points "disappear" leaving me with a poor-man's ball-end, and I see oxidation colours a short distance up the shaft.
Looking at @jcdammeyer's feed chart, I realize I'm probably taking too deep a cut with these tiny end mills. That will be my next test.
Click to expand...

I would say too high on the RPMs and to deep a DOC. Those little EMs need to be fed slowly.
 
Dabbler said:
What I use fo coolant is a ZEP sprayer with soluable oil in it. Squirt as needed. Does a great job, and less mess, no sump clean out.
Click to expand...
That's the other thing about the "Machinist Toolbox" program. It's not clear, but I assume that massive flood coolant is expected for the feeds and speeds. Which is another reason why I cut way back.
 
I'll say it again CARBIDE (and yes you are going to destroy a few while you figure out the feeds and speeds for your machine as we don't have the 100hp, 15,000rpm 1000psi thru spindle coolant).

Mist cooling works (I have it but your compressor runs hard).

I prefer flood coolant (yes messy but sigh it does work).

Now speeds and feeds are kinda messed up, old school slow rpm and slow feed with good engagement and cutting oil and HSS. New school high rpm with fast feeds and high engagement and lots of flood cooling fluid (as lots of heat is generated) carbide cutter.

I prefer synthetic ionic coolant (Microchip because its easily available and cleans easy from KBC) basically it doesn't really lubricate like a cutting oil but evaporates (chills) both material and cutter while removing chips.

In my applications in Aluminium I have finally figured out the balance for exceptional cutter life, good speed cut and good finish. Working on improving the mess.
 
PaulL said:
Having done Bad Things(tm) to too many end mills I'm thinking it's time to sort out coolant on my First mill.
It has a built-in pump, but it's not running - I need to move it 24" away from the wall and do some debugging in there if I want it to run. The machine is designed to filter/cycle fluid from the sump it seems, which also doesn't seem to have any tidy clean-up facility. I expect the sump to get pretty gross.
I've also been looking at mist coolant systems, which would save me moving the machine. These are so extravagantly cheap that I'm probably going to press the button before I finish this paragr...ok, done, and I'll report on it when it arrives, oh, on Monday. That's too soon, so I'll report on it once the insulation is done in my shop.
And now that I've spent 40$ on a stop-gap, is it worth getting the flood coolant going on the mill? I have no experience with either flood nor mist.
Click to expand...
I had flood coolant in my band saw and stopped using it. It makes a mess. And if you don't use it frequently it turns to snot and the whole system needs to be cleaned. I too have looked at mist coolant and its appealing but for now I just use a squirt bottle. I don't use coolant on either my lathe or mill for the same reasons. Slower speed and feeds plus some cutting oil applied with a brush or bottle seem to do the job.
 
On the bandsaw it came with cooling it works but I agree on large work it does really create a mess. Over all I see little benefit on the materials I cut.

On the lathe currently none, on the previous I used it a fair bit, I found switching to carbide inserts greatly reduced the need.

Mill, here definite advantages, mist cooling is works but in terms if flood cooling definite advantage. Considering the mill is now CNC it is a must.

I am a bit beyond hobby usage and work to a schedule (so time is not my friend) production is.
 
I am another who stays away from coolant unless drilling on my mill.
I use air for all carbide endmills, ball nose and indexable tooling. I find you can get much faster feedrates and chip evacuation is perfect. On my manual mill I just use an airline with link line, also a small bottle of cutting oil ( rapid tap )
 
PaulL said:
HSS. Cheap ones in from AliExpress. Even the larger ones have failed quickly.
But I've also burned up a 3/8" mill from KMS, so I'm leaning towards a technique problem.
Click to expand...

Forget about the hss, if your milling steel grab some carbide from AliExpress and don't look back, the smaller stuff is dirt cheap
 
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