Cutting fluids

[ajoeiam]

Nice to recognize the different opinions on cutting fluids. In our horological society and its light cuts we mostly prefer pure oil cutting fluids, applied with a dispenser or just a brush. Some members use in their home workshop 'mist' or cutting oil applied with air. Two problems here 1) when the air pressure is high and/or ill directed the air will force chips and dirt between sliding surfaces 2) the oily mist will eventually find its way all over the place - on the walls and the ceiling of your workshop, but also in your lungs. So our members with a medical background most strongly advise against 'cutting mist'.

This physical 'problem' is one of the very much (imo) understated hazards of using cutting fluids - - - - even the water based emulsion ones! Unless you are really pouring on the coolant you will get some vaporization - - - those chips are HOT - - - and that vaporized coolant carries on of its goodies with it. To date as an asthmatic I haven't had any issues but I have become much more aware of any issues.

 

[Mike Ginn]

Interesting comment re misting with oil. I have long been concerned about the spread of mist oil. If I paint spray in my workshop without using a cabinet (cardboard box!) I find that there is a layer of paint coloured dust on flat surfaces. Easily removed but not if oily - think grease from excessive sausage frying in a badly vented kitchen - not good. I guess a water based system would be better but there will be a residue.

I had never thought of the respiratory issues. Good call and warning to us all. We modellers are generally retired (gross simplification!) and need to be aware of respiratory triggers. Although off topic, re lubrication, I would highlight breathing silicas especially from the use of cheap sand blasting media - always use ground glass or other safe media. Glass is really cheap but not as available as a bag of play sand in the local B&Q/Home Depot.

Conclusion. Very interesting discussion which has thrown up some new-to-me lubrication techniques. Air blasting, misting, water based systems, oil and paraffin, WD40 etc etc. Its been very hot here in the UK and sleep has been hard to achieve (no AC!) so I have had ample time to think through my lubrication strategy. My conclusion is to stay with pumped cutting oil and for simpler lathe and mill machining to use a brush and tin of oil.

Thanks for the constructive comments

Mike

 

[mcostello]

I have misted both black cutting oil and Trim mist 77. I have no problems with either in a 16'x16' shop that is fairly tight. The black cutting oil is for a heavy duty slotting operation that is 3/8" deep x .052" wide in 303 stainless steel. The Trim mist is only used a couple of times a year. Usually black sulfur oil is applied with a small brush. No unwanted deposits, slight smell, no rusting, been using for more than 10 years.

 

[giel]

Nice to recognize the different opinions on cutting fluids. In our horological society and its light cuts we mostly prefer pure oil cutting fluids, applied with a dispenser or just a brush. Some members use in their home workshop 'mist' or cutting oil applied with air. Two problems here 1) when the air pressure is high and/or ill directed the air will force chips and dirt between sliding surfaces 2) the oily mist will eventually find its way all over the place - on the walls and the ceiling of your workshop, but also in your lungs. So our members with a medical background most strongly advise against 'cutting mist'.

that is why machines are mandatory to have a good filtration system on them and a full enclosure on them when using cutting fluid off any kind beqause it is cancer flying in the air!!

+ when working with oil as a cutting fluid you are mandatory to have a fire extinguisher system buildt into the machine + a extinguisher on the outside

+ if machining magnesium etc YOU MUST PLACE TE MACHINE ON A PALLET or in a separate closed area.
so in case of fire it can be placed outside quickly! with a forklift or something

looks like this is over the top but metal fire is almost to put out!! when it happenda you don't want to lose your whole machine shop...

thats also the reason machining magnesium is expensive and only very experienced people are allowed to do so.

this is the case in the Netherlands (i don't know how they are thinking of personal safety in the rest of the world)

 

[giel]

and for aluminum machining (at home) a mist system with alcohol (IPA) is working very good, also watch out for fire ( never had a fire in 10 years) also but it has the big advantage that it will vaporise very fast and you can vacuum your chips easy..

little side note USE IN A WELL VENTILATED area/air extraction system.. beqause you will get drunk in 2 minutes of breathing alcohol!

 

[dazz]

beqause you will get drunk in 2 minutes of breathing alcohol!

That sounds fantastic

 

[Mike Ginn]

As a teenager I visited a local factory which made it's own screws (BA). The automatic machines were fascinating to watch and they were flooded with neat cutting oil. I was told this was to give a smooth finish, to prevent material build-up on the tool and to lengthen the life of the tool. On subsequent visits I watched soap water suds being used in larger machines and generally on lathes.

More recent posts talk about air systems to cool the tool and IPA misting. I really struggle to understand how these can work not to mention the risks of atomized IPA.

The question that needs to be addressed is:- What is the purpose of these lubrication/cooling systems? Are they specific to certain types of machining operations. (I could see misted IPA being used on a very small lathe but not for instance on a 6inch mild steel flywheel.) I guess I am asking what is the science behind these different types of what I will call lubrication-cooling?

I remain confused - but that's not unusual!

Mike

 

[timo_gross]

As a teenager I visited a local factory which made it's own screws (BA). The automatic machines were fascinating to watch and they were flooded with neat cutting oil. I was told this was to give a smooth finish, to prevent material build-up on the tool and to lengthen the life of the tool. On subsequent visits I watched soap water suds being used in larger machines and generally on lathes.

More recent posts talk about air systems to cool the tool and IPA misting. I really struggle to understand how these can work not to mention the risks of atomized IPA.

The question that needs to be addressed is:- What is the purpose of these lubrication/cooling systems? Are they specific to certain types of machining operations. (I could see misted IPA being used on a very small lathe but not for instance on a 6inch mild steel flywheel.) I guess I am asking what is the science behind these different types of what I will call lubrication-cooling?

I remain confused - but that's not unusual!

Mike

I think pretty much, confusion probably is our fate, because it is complex and not becoming easier with additional options for cooling and cutting tools.
I guess people who are not confused, are either just clueless or can make a living as "cooling-consultant".

Following my dangerous half knowledge from uneducated observations and reading, there seems to be no "one fits all, good for everything" solution.
One manufacturer for milling inserts advised me to use my surface mill without liquid coolant. The guy explained that the liquid coolant accelerates surface cracks because of rapid temperature changes between engagements. A light air blast helps with chip removal, without "shock cooling" the inserts.
That tool works fine on steel without any cooling.

Some ceramics (or hard carbide materials) are designed to cut steel dry, those cutters are designed in a way that most of the excess heat ends up in the chips.
I saw a big lathe cutting steel dry that way. Those will sometimes use air to assist chip transport and prevent "recutting" chips.

Certain tools tend to create a build up on the cutting edge when machining Al, those are often lubricated and cooled with water soluble oil.
I bought some polished carbide cutters for Al, they do not work without coolant. (the flutes clogg up and the cutter brakes)
The datasheet of the coolant says "not suitable for cast iron".

I recently visited one shop they use Oil for the CNC lathe making small parts with a lot of threads and small features.
Same factory used water soluble coolant for the milling machine.
Different machines, different material (cutting tools) all seem to have their approach. Then you will find more traditional approaches and "newer methods", I guess all that mixed with a good amount of regional taste and preference, influenced by environmental and work/health regulations.


Greetings Timo

 

[Mike Ginn]

Its a good post Timo but there is one omission concerning us modelers. In general we don't use exotic inserts or high load deep cuts and our materials are limited - if indeed we know what grade they are. So given that, and returning to coolants, can we say what is the best approach?

Full disclosure - I am only using pumped or brushed cutting oil for everything!

Mike

 

[stanstocker]

Its a good post Timo but there is one omission concerning us modelers. In general we don't use exotic inserts or high load deep cuts and our materials are limited - if indeed we know what grade they are. So given that, and returning to coolants, can we say what is the best approach?

Full disclosure - I am only using pumped or brushed cutting oil for everything!

Mike

Hi Mike,

Pretty much all the different ways for cooling, lubing, clearing the cutting area do the same things from a high level. Remove the chips from the work area, improve surface finish, prolong tool life, and improve as machined accuracy of parts by providing thermal stability. In a lot of cases, as much as 80 percent of the heat is removed by cutting feeds and speeds making chips that take the heat away as they fly away or are blown / washed off. Or so Sandvik and other folks who should know have said. Removing chips avoids recutting of swarf. If you are recutting chips, you get lower finish quality, excessive tool wear, and lower dimensional accuracy. In the home shop, if the part is hot to the touch and we care about holding a close dimension, we can just wait a few minutes for it to cool off, check dimensions, and take our final pass or passes to get it right. In manufacturing, you rough hard and fast then do a final pass for dimensional accuracy and finish quality. Water soluble oil coolants tend to be used in high volume and pressure on larger work pieces, like CNC mills. Wimpy little "flood coolant" setups often seen on homebrew CNC machines just make piles of coolant soaked chips that you still have to brush clear to avoid recutting. MQL or mist coolant devices tend to provide some cutting and cooling action, but the air blast is hopefully clearing chips from the working area. Screw machines, AKA Swiss lathes like those from Tornos, tend to use pure oil as the nature of chip formation and cutter setup and forces is quite different from those in mills, and the parts they are used for also are difficult and costly for any finish cleanup operations after machining. Ever tried to polish the threads on a 0-80 screw? Now consider making thousands at a time. Better to have perfect threads and screw heads off the machine.

My defaults are kerosene (paraffin in the UK) for aluminum, sometimes isopropyl alcohol for very fine intricate cuts. Heavy thread cutting oil or Vipers Venom cutting oils for steel. Pretty much any smelly cutting oil that's thick. Brushed on is the most used method of applying.

I can run a mist coolant setup on CNC stuff, set to be fairly wet to avoid too much crud in the air. I really should build a nice little MQL setup I guess. Quite often on the little Sherline CNC machine I run just an air blast to remove chips and avoid recutting, particularly in brass when using quite small cutters.

Exotic inserts are sort of a user defined concept. To me a $10 insert is not unusual, but a $40 PCD insert would be. I'd use one if hard material cutting was needed for a job, but then it's not exotic, it's just the right tool for the job. The highly polished boring inserts for aluminum are truly lovely to use with kerosene as a coolant, but quite often plain old boring HSS well honed ends up being my cutter of choice while the really nice expensive polished insert tool is reserved for final passes where the time to swap tools is justified. Most of my machining these days is keeping stuff working and utilitarian though, hopefully time for nice little engines and such will be available soon.

Trying to do home shop work "like the big shops do things" is something I realized isn't practical in many cases. Industries needs are different than mine most of the time. I worked for a while in a large defense plant. We had lovely exotic machines, flood coolant that ran through huge pipes, every top of the line latest and greatest way to accurately and repeatably remove metal in high volumes at speed. When I needed to have a test fixture made one off I'd head down to see the guys in the model and prototype shop. Most of the machines were still old school but very, very, good manual and power feed rather than CNC back in the early 1980's. They were using jars of cutting oil and flux brushes or small squirt bottles for most stuff, just like me in my little home shop

Best approach? No idea, just what works for me with my equipment.

Cheers,
Stan

 

[timo_gross]

Its a good post Timo but there is one omission concerning us modelers. In general we don't use exotic inserts or high load deep cuts and our materials are limited - if indeed we know what grade they are. So given that, and returning to coolants, can we say what is the best approach?

Full disclosure - I am only using pumped or brushed cutting oil for everything!

Mike

I would not know, I am more on the confused side of things, less on the "cooling-consultant" side as I say more dangerous half knowledge and what I try to find out, by asking people for advise. I have the feeling the cutting oil is not such a bad solution for what you do.
I am thinking of trying cutting oil with pump for the small gear cutter, if not the best approach at least:

"like the big shops do things"

approach fun project I hope.

Greetings Timo

 

[awake]

... concerning us modelers ... can we say what is the best approach?

Yes, absolutely. The best approach for a modeler is "whatever works"!

Yes, sorry, not actually a helpful contribution to the discussion ...

 

[Mike Ginn]

Guys
I have really found these post very helpful and I think that Andy is spot on - your first sentence sums up what we should all aim to do. "If it works don't fix it!"

Many of these posts are worth a second read as they contain a wealth of experience - thank you.

I had dismissed the use of air/airmist as a means of cooling the cutter but it seems that the most important attribute is to clear the chips - this had not occurred to me but having said that I have always used excessive oil onto knurl wheels to clear the chips!

My new approach is to continue to use cutting oil on the lathe but to try/use a low pressure air jet on the mill to clear chips. Why not oil? I don't have a good collection system of oil guards on the mill so air would be much better at low pressure.

Mike

 

[Toymaker]

Guys
I have really found these post very helpful and I think that Andy is spot on - your first sentence sums up what we should all aim to do. "If it works don't fix it!"

Many of these posts are worth a second read as they contain a wealth of experience - thank you.

I had dismissed the use of air/airmist as a means of cooling the cutter but it seems that the most important attribute is to clear the chips - this had not occurred to me but having said that I have always used excessive oil onto knurl wheels to clear the chips!

My new approach is to continue to use cutting oil on the lathe but to try/use a low pressure air jet on the mill to clear chips. Why not oil? I don't have a good collection system of oil guards on the mill so air would be much better at low pressure.

Mike

Hi Mike, I've been using low pressure air on my benchtop mill for several years and find it works great at blowing chips away from the end mill and keeping it cooler.

A few years back I purchased a small air/vacuum pump from eBay and wired it to a motor speed controller (also from eBay) which allows me to vary the amount of air & pressure. If you're a bit handy with electrical wiring this is an easy solution. The pump I bought was $17 with shipping. These little pumps all use DC around 5V to 12V with a few going up to 24V, so, if you don't already have one, you will also need an appropriate DC power supply.

 

[stanstocker]

Guys
I have really found these post very helpful and I think that Andy is spot on - your first sentence sums up what we should all aim to do. "If it works don't fix it!"

Many of these posts are worth a second read as they contain a wealth of experience - thank you.

I had dismissed the use of air/airmist as a means of cooling the cutter but it seems that the most important attribute is to clear the chips - this had not occurred to me but having said that I have always used excessive oil onto knurl wheels to clear the chips!

My new approach is to continue to use cutting oil on the lathe but to try/use a low pressure air jet on the mill to clear chips. Why not oil? I don't have a good collection system of oil guards on the mill so air would be much better at low pressure.

Mike

Hi Mike,

Actually keep flooding the oil onto those knurling cutters. You are doing both a cutting and a forming process simultaneously when you "cut" a knurl. And shavings from the cutting part of the process either get floated away or end up mashed into the surface giving a poor result.

I should have mentioned also that some jobs get a shop vacuum rigged up, sometimes with a crevice tool, for chip removal. Not only does it handle the chip removal, it saves you lots of clean up time. Not so great if your cutting requires a lube for finish quality, but perfect for stuff you cut dry like cast iron and brass. As both of these make nasty little chips and crumbs when they cut dealing with the chips as you cut sure makes the day go better.

Rather like in woodworking, if you handle the sawdust / swarf at the point of creation your shop stays a lot cleaner and you spend a lot less time sweeping up.

Take care,
Stan

 

[Mike Ginn]

Stan and Toymaker you both make good points. I have used a vac to remove chips but the down side is the noise and the need to have a "reasonable" sized nozzle to prevent blocking. I like the small air pump. Never thought of that and being small I guess its reasonably quiet. My alternate approach is to make use of my 50Ltr air compressor reduced to say 10psi or less with a very small nozzle. It has the advantage of being almost silent (until the motor cuts in) and it is available now. I would use the external pressure reducer to control the air flow and the distance the chips are thrown.

I can see a busy weekend ahead!

Thanks

Mike

 

[Toymaker]

Stan and Toymaker you both make good points. I have used a vac to remove chips but the down side is the noise and the need to have a "reasonable" sized nozzle to prevent blocking. I like the small air pump. Never thought of that and being small I guess its reasonably quiet. My alternate approach is to make use of my 50Ltr air compressor reduced to say 10psi or less with a very small nozzle. It has the advantage of being almost silent (until the motor cuts in) and it is available now. I would use the external pressure reducer to control the air flow and the distance the chips are thrown.

I can see a busy weekend ahead!

Thanks

Mike

Yep, the little pump I have (the one in the photo) is so quiet that I sometimes forget to turn it off after I've powered down all the other equipment,....because I can barely hear it running.

 

[giel]

the water soluble coolant is cancer in a bottle!!! ipa is used to cool and keep flying chips to a minimum..just needs a good ventilator on it to get the mist out instead off inhaling it.. same goes for oil/emulsion cooling .

the little air pumps àre great for mist cooling.. only downside is the lifespan of these pumps.. 700hr they quote on full power