Milling machine coolant Yes or No?

bryan

bryan

Bryan Armatys
Is there a general rule of thumb regarding the use of coolant when milling? I'm just learning and have a RF 31 clone mill/drill.
Also, is there a chart available on feeds/speeds for different materials?
I plan on taking a course from Speedy at TSJC, but for now, I just don't want to develope bad habits.
All info is appreciated.
Bryan
 
I don't use coolant or mist on my mills because it is a mess to clean. I do use cutting oil for drilling steel and all tapping operations. I do all my tapping in the mill or lathe. No hand tapping for me.
Butch
 
Major mess! Never used a mist, I would think there would be less coolant flying around, but still, it gets everywhere.
 
I do use coolant on the the verticle mill on some jobs. One in particular is a .5"deep x.234 slot at 45deg. This is a 5ft long cut in 6061 alum. It floats the chips out, and keeps the cutter from loading. It is a tad messy. I get much better tool life and a better cut with this approach. On some small cuts I might just use a hand spray bottle to cool the cutter and part a bit. None of what I do is cnc or high production where flood coolant is the rule.
 
I will admit, that cutting aluminum needs something or it just loads up on the mill. I use cutting oil and some air to clear things out, but not a steady flood.
 
Use of coolant depends upon a number of things. Leaving the mess issue alone, I'll try and address a couple other things that are going on.

I get my information from machine tool tech support guys, the help of colleagues, and my own experience. Take that for what its worth.

Ok, there are a couple ways to look at this. If for instance a guy is using a solid carbide or insert type end mill then you generally have two choices. You either use a coolant or you don't. What you don't do is use MIST and here's why, it fractures the tool and causes greatly accelerated wear. Especially when the tool is coated.

Now, there is a major difference between coolant and cutting fluid/oil. Don't confuse the two.

A cutter enters the material and it either "cuts" by a cutting/shearing action (conventional endmill) or it uses a combination of pressure and heat transfer (carbide insert type tool) to bring the material to a molten state and tear it from the stock.

In the case of carbide the isolated pockets of rapid heating/cooling caused by a mist type coolant set up will cause fracturing and accelerated breakdown along the cutting edges. The tool will dull much quicker than if it ran dry or with a bit of lubricant to help avoid material transfer. (very important in case of aluminum since it's so sticky/gummy when being machined)

Carbide insert tools don't like mist coolant either generally and they too will break down sooner.

HSS and/or Colbalt cutters however almost have to have some kind of coolant to mitigate the tool from overheating and annealing itself. The Cobalt is there just to extend the heat tolerance of the tool a little more.

The use of coolant is important when working with certain types of tooling, a great deal of effort is invested to the sophisticated flood and through tooling coolant systems used in today's machining equipment. It serves a dual purpose. One is to cool the tool and two is for chip evacuation.

Hope this helped. If a guy wants to know more just go to any major tooling company's website (SandVik, Iscar, Kennametal, etc) and do a little reading. It's helpful.

Cheers,

Chad
 
Thank you Chad !

Hello Chad, I would like to use this post to thank you for your help regarding the hard bolt lift on my Nesika "J" model. As per your instructions via several e- mails I was able to correct the problem by following your instructions on how to check and how to correct the problem. I appreciate your time and generosity in helping me with this problem. I hope other people on this forum realize and appreciate your willingness to help others. Chad, the bolt on my Nesika feels great now, again, thank you kindly.
Roland
 
Chad, Good reply . .

There are some other things that come into play with coolant and the use of cutting fluids. Chad had all the general answers to doing it, if you are doing a lot of material and want to keep both the cutter and the work piece from heating up. It also depends on the cutters that you are using, if you are using a small end mill on a piece of mild steel, you may want to just use a little oil on it to keep it from loading up and keep the finish - decent. Speeds and feeds also come into play with it, too fast and you will tear up a cutter or burn it into the part, depending on the material and the cutter. There are some materials that just need some sort of coolant - Titanium being one of them that I seldom had good luck cutting with out it, depending on the depth of the cut and size of the cutter, and weather I was using the end of the cutter or the side of it. Chad also hit on one thing about coolant, it will keep the chips under control, uses it to wash them away, and cooling down the work piece, both a plus for big machines, especially CNC's, some of them will go over 20" a minute, that's a lot of chips to get rid of.

There are books out there to set speeds and feeds with, and they are as general rule very good. Time and experience will be the best teachers, and if you are just starting out as a machinist, you will tear up cutters and mess up jobs and material, and learn from them. They have come a long way with the coolants in the past 20 years, I don't care much for WD-40 for Alum, but it works, there are better materials for that, just cost a bit more, but do a better job in MHO.

A lot of what you will use coolant on will depend on the machine you are using, a big mill will need coolant, a small bench mill - you will likely just have a can or container of cutting oil and an acid brush to apply it with. Again, depending on the material and how much of it you are taking off. . . Experience. I have a small bench mill and have yet to run any coolant or mist on any thing I have had to mill on it. But I have run Cinci CNC's that don't work well with out it. Some materials you will not want to transfer a lot of heat to the part, it will, depending on the speed of the cutter and the feed that you are using, heat treat the spot where the cutter is (supposed to be) cutting. Again, experience, slow down both the cutter and the feed, and you will be supprised the job will get done, it is not a race, just dollars.

Then - it equates to if you want to go fast and clean up a mess that you created - or, slow down and take the time to do it right. If you have ever watched an OLD Machinist - it looks like he is in slow motion . . he is, because he only wants to do it one time . . right !! Does the haire and the tortus come to mind . . ? Back in the early 60's when I started out in a machine shop, I was a bit aprehensive about too much speed and feed. My boss told me speed it up till you burn up the cutter - then back off . . I always considered that a bit over done . . but I learned to run the machine till the chips hit the floor like Quarters, he loved it . . .

Most likley got way off the subject, but after over 45+ years in machine shops - and now in my retirement (7 yrs) I am still running them, you learn the ways. Think ahead . . . .

Phantom496
 
Yup, they will move that fast . .

Yes, they will go that fast, but - as you say on alum, it is alright, but usually with fly cutters or such, not end mills . . The popcorn oil sounds like a cool idea, that would sure make the place smell goooood. . . We had a couple of Mazaks that would run up to 100 ipm, but usually just to go get a new tool, that was fun to watch do . .wow !! When you start watching that kind of equipment go that fast, you stand and stare like a Doe in the headlights . . :eek:

I hope the fellow that started this link has what he needs - been interesting.

Phantom496
 
How about some thing specific. I am cutting 17-4 condition 900 at 5 ipm, 1200 rpm, 1/32 deep per pass up to 3/4" deep or so with a 3/8 4flt carbide end mill. I have been using mist and hate the mess, how will that do dry. I haven't tried it, I just assumed that you had to have some lube and I don't have the option to use flood right now.

Thanks Gary
 
Thanks for the info

Guys, I'm a beginner, but the info here has been well noted. Lots of talk about the mess:( Right now I just deal with chips in a 360 degree circle of the cutter, and with lube/coolant it would be a wet mess of chips in the same circle. But if tooling lasts longer and the finish is better.........I'll get some shop aprons and spend a bit more time cleaning up.:mad:
Thanks
BA
 
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I have allot of fluids in the shop and shop annex, but the ones that really get used are:
1) Cool Mist formula #77 mixed 10:1 with water in a plant sprayer bottle with the nozzle adjusted to a stream, not a spray. This is squirted on:
..a) Lathe cutting steel or stainless steel with Cobalt or HSS tools.
..b) Lathe drilling on center with high speed drills cutting steel or stainless.
..c) Drill press drilling with high speed steel drills cutting steel or stainless steel.
..d) Mill drilling or milling with high speed steel bits cutting steel or stainless.
2) Sulfured cutting oil
..a) Cutting rifle chambers with a reamer
..b) Cutting rifle barrel threads with high speed steel bits
3) Tap magic regular for tapping steel or stainless
4) Tap magic Aluminum for tapping Aluminum.

What does not get fluids when cutting:
1) Cutting wood.
2) Cutting Aluminum
3) Cutting with carbide tools

My choice of Cool Mist, is that:
1) Does not stink
2) Does not irritate respiratory system
3) Does not allow the water to rust steel

My lathe came with a coolant pump and nozzle. I don't use it. I like the spray bottles better.
My brother uses his coolant system for compressed air, to cool bolt handles between welds.

http://www1.mscdirect.com/CGI/NNPDF...231889&PMT4TP=*ITPD&PMITEM=09413436&PMCTLG=00
 

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Thank you Chad !

I want to thank Chad Dixon (Nesika Chad) for helping me re: a hard bolt lift problem on my Nesika "J" model. His help consisted of several e-mails which he took the time to answer. Following Chads instructions I was able to make a great improvement on the bolt lift on my Nesika. The bolt now has a nice easier lift on it. From reading the forums I noticed that Chad has helped many people with his knowledge and willingness to share it. Thank you very much Chad. I appreciate it.
Roland
 
My son was a Mazak engineer. They experimented with high pressure coolant. 2,500 psi coolant extends tool life 10 times over flood coolant. Not really practical for the home shop. You can use the mist coolant system without the liquid and get about 80% of the benefit of using it with liquid. It keeps the tool cooler and clears chips. There are dedicated cool air rigs, but the mist unit is readily available to the home shop.
 
One more thing to concider is the coating on your endmills. I use a lot of TiALN coated endmills and never use a coolant in steel. The TiALN does not get slick until it hits better the 1000 degrees f and if you use coolant the coating will blow off, leaving a bare edge that will dull quickly. There are some feed and speed tools out there on the internet. I use MEPro as a double check. Feeds and speeds are so important to good work.

Lowell
 
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