Milling Aluminum: Cutting Fluids Tested! 

Quite interesting results, thanks !

I know I'm 2yrs late ~ Have you tried Methalated Spirit, in a hand held squirt bottle. It's what I grew up useing. It evaporates like the Ethanol but not as fast, it will stay pooled on the job for cooling, while having a mineral based lubricating action as well. I am impressed with the WD40 finish you got !

Great video, well formatted! From what I saw, WD40 was the only fluid to run down to the bottom of the aluminum, where the tip of the bit is. This means that it was the only fluid to lubricate the tip whereas the other fluids only lubricated the side of the bit. I have a rickety home made router and use flood coolant (water based oil, same as what is used on lathes) this helps a stack. Gets rid of chips in your slots and you can run the spindle as fast as you like because the Aluminum cant get hot enough to bind.

Thinking purely from a physics point of view, the stacked coins occur when the end mill is not perfectly parallel to the material. You could be getting a very slight digging in as it goes from side to side. The improvements with the various fluids would suggest they are reducing the digging in by allowing the cutter to slide more easily over the surface of the material. Taking small finishing passes is the obvious solution - try a couple of passes at 0.002in.

Thank you! Great pro test.

Super helpful video. thanks for posting! :D

Exaxtly what i needed today. Thank you

I use canola oil for milling, drilling, turning and tapping

Outstanding!👍👍👍

I would be interested how GT85 works for you? It’s a PTFE lube spray. I’ve found it helpful on plastic and alu cutting to avoid chip weld. I mainly spray the cutter and perhaps splash a bit around the part on a larger job.

Ethanol is good to keep everything cool, to avoid aluminium to stick on the cutter because of heat. The issue with aluminium is that a little bit of material tend to stick on the tip of the cutter during the cutting, so it leaves marks during the rest of the rotation. Best choice is the flood coolant with a % of 5~10% oil. If you can't, light oils like WD40, but also plain kero, diesel fuel and so on are good, but they make fumes and they're quite flammable. I'm a professional metalworker but also a hobbyist, since after work I'm playing with metals, so I have some experience in both the fields. In last months I'm playing with a DIY CNC to make alu molds for injection molding, on a small milling machine without flood coolant. For those I tried various fluids, especially because I'm working in recesses (so I can flood the recess with fluid) and since the process is long I need something who stays in the recess while the machine is working and I'm drinking a beer with friends. 😉 It turned out that ATF fluid is a very good cutting fluid for aluminium. It's quite messy to clean out after the work, but it give good surface finish and it avoid totally material sticking on the cutter. Cheers from Italy!

Could that marks come from the spindle not quite being perpendicular to the Y axis movement? (Looks like the edge of the end mill scratches deeper on one side than on the other)

You can get Everclear in 95% Ethanol (Alcohol) by volume. I'd guess the other 5% to be Water. 1.75 Quarts (Liters) for ~$32. Thanks for the test!

nice video, which oil i have to use for aluminium extrusion cutting ( this is for MQL Type)

I learned the majority of what little machining skills I have from an old-school machinist who was formally trained as a woodworker. This guy was obsessive with perfect part finishes and always swore by kerosene as the best cutting fluid for non-ferrous metals. I'd be hesitant to use mineral oil or ethanol in anything other than light hobbyist work as they both tend to degrade wide ranges of polymers (e.g. paint, perhaps your way covers).

is any natural coolant oil like vegetable oil or castor oil can be used of cutting fluid. or can you suggest me any other natural coolant oil for cutting fluid

You should try a mister. That would keep a film on the part, and keep volume lower than flood.

they make a thing called a drill mill, it has the start of a drill and the flutes of an endmill.

Does the feed rate affect the finish quality? I don’t get very clean looking finish, although it’s very smooth to touch, but one can see the scuff marks on the surface. The material is 6061 aluminum, 6.35 dia carbide end mill, 2 flute. Feed is F120. The coolant is cutting oil mixed with water, flood type with air blower.

Many years ago kerosene was used as a coolant in surface grinding

WD40 is deoderized Kerosene with a wee skosh of hydrotreated light pump oil. Kero does the job too for a shit ton less $$

Can you use Tap Magic on aluminum?

Thanks for sharing your work! Did you 'degrease' the cuts done with oily fluids before taking pictures? I am asking because it could be that residue in the groves hides the marks. Kind of how wood becomes darker when wetted... I used to use WD40 for cutting aluminum with a fogbuster. It works, but I could really feel it in my lungs after some time in the shop....

Try adding a mister. And it looks like most of the finish problems are from rigidity in the spindle column.

Is that 2.2kw air cooled spindle upgrade? Whats is the main advantage you gained upgrading from 1.5kw? Thanks.

Do you have a link to that black cover thing to your rails and leadscrew? Thanks for the info. Ive only tried dried cutting and air blasted. Will try wd40

What would you say is the best option for the preservation of the end mill bit?

Well…. You leave some issues uncovered. The 6061 aluminum is a large part of your problems. It is a rather gummy alloy, with any of its available tempers. A rather long endmill is not a friend. Using a stub length cutter with .01-.03” corner radius, or even a carefully ground micro-flat, slightly wider than your feed rate can help. K1 kerosene was a highly recommended drilling and tapping fluid in the early sixties, before the tap magic etc. were added to catalogues. So was a paste of white lead and sulphurised cutting oil. If you get a piece of 7075 T651, you may like the results. Painting oil on a surface ahead of the cutter doesn’t work well, as it moves away from the area of contact, either from heat, or air turbulence.

Please another cutting test with cheap vegetable oil and cheap car motor oil (or is this mineral oil???).

Not perpendicular spindle?

Breakfree isn't a 'newer formulation' its been around for ~30 years.

Hello I bought out a warehouse with lots of 5 gallon buckets and 55 gallon drums of cutting fluids of various styles would anyone be interested boxes and boxes of various carbide tips and bits

I'm so old I used to use WD-39.

Though I have not tried it myself I was told by an Engineer that kerosene is the best for aluminum.

The typical WD40, that you can get pretty much everywhere isn't actually a lubricant at all. It's the opposite and should not be used as such. That's why you notice it doesn't hold up as much for things like squeeky doors. Over time it removes every lubricant, that was on there before and makes it worse. It is supposed to loosen up rust and to clean parts and it removes thicker grease. Yes it does work very well as coolant on aluminium parts. For that purpose it is fine and is therefore used by many people for that purpose. You also can also use WD40 to clean parts, without making them vulnerable to rust (or actually protect them from rust), but never use it as lubricant. For lubrication the WD40 should be removed with alcohol, acetone or brake fluid (or similar) beforehands and then you can use a suitable lubricant afterwards. However WD40 is actually a brand name and not the name of a specific product. They also make a few other products, that appear to look very similar on first look, but some of these other products are actually lubricants for various purposes.

You should try kerosene and diesel

I don't like A9- it's perfumed, so it makes me sneeze and itch.

usare alcol ciao

You better oil every bit of that machine after you use ethanol. Ethanol will cause that thing to rust so bad

WD 40 is not a lubricant.