99,5% Aluminium sheets milling issue

[reyntjensm]

for some reason i came across a huge CNC router machine, the table size is 6*4 meters. The goal with this machine is to mill aluminium sheets ( 1,5 or 2mm thick). The sheets are kept in place with vacuum, below the aluminium sheets is a 6mm mdf waste board. As these sheets are 99,5% pure aluminium it's very sticky and difficult to mill. I've tried 30 different endmills with different settings, nothing worked out until i found out about PCD endmills. The PCD endmills are coated with diamonds and crazy expensive. It's a 5mm straight 2 flute endmill. It took a long time to figure out the settings but i made it work. While trying this i was always using an oil mist as cooling/lubrication. The endmill manufacturer told me no cooling/lubrication was needed with PCD endmills. So i tried without cooling and it works 99% of the time, until at some point the chips start to stick/melt for some reason and i need to jump to the emergency button. So to avoid these scenarios i want to use some kind of cooling/lubrication but it should be as clean as possible ( read: no oil). I have found some topics online suggesting to use a cold air gun. Does anybody have experience with this? Also i would like to use IPA since it evaporates, but i'm a bit scared about the potential fire hazard? Tips are welcome!

EDIT: i found a thread from a few years ago related to my issue. If it doesn't fit this forum i'm sorry to post here. I was already surprised to find some related info on this forum.

[AmnevaR]

There are 1-flute inexpensive chinese endmills specifically for cutting aluminium. The more flutes you have the more babysitting near machine is required if you are cutting pure aluminium. I don't think the coolant is required at all if you will manage to blow all the chips out of cutting path using compressed air. If the chips are evacuated properly, they will not be cut again and stick to endmill or to material. I hope something that I wrote makes sense 

[langwadt]

try a 1 flute (sometimes called O Flute) ethanol is absolute magic for stopping aluminum sticking to tools, it is flammable but so is vodka and hand sanitizer and you don't need flood everything, just few drops will do. For small jobs I just use a spray bottle.

but it will quickly ruin your mdf spoil board by making it swell

[SilverSolder]

+1 for ethanol, works for drilling, tapping, and machining aluminum, leaves no mess.

[Tarloth]

+2 Ethanol 70% it's enough, but as said by  langwadt ruin your MDF spoilboard

[coppercone2]

Whats wrong with oil?

I don't have experience with diamond mill tooling, but I understood that no oil is only for dealing with super alloys. Super alloys when machined by diamond experience a red hot surface temperature, i.e. the endmill is red hot... in this situation the oil would likely burn and stick to the tool. Are you sure they are not just saying that no oil policy incase you decide to stick a sheet of inconel on the machine?




I like to use diamond bladed saws though, for angle grinders and chop saws. I put a 14 inch diamond blade on a chop saw and I cut through a 4x3 inch solid aluminum block to make plate slices. When I cut, I spray it down with wd40 as its cutting. If I don't spray it with wd40, the diamonds get clogged. If you need to cut aluminum on a diamond chop saw (and I mean the metal cutting diamonds, not the tile cutters), just keep it sprayed on... and I am pretty sure I did some cuts with silicone WD40 and there was no problems either.

When I did comparisons with carbide endmills on aluminum (freshly acetylene oxygen gas welded soft stuff), I found that regular wd40 works well. I tried to use alumitap from tap magic, which is what I use for tapping... anyway alumitap makes the endmill clog, I suppose its only good for low speed work with a  tap. So long I kept spraying wd40 fairly frequently I managed to machine a great deal of aluminum weld without any clogs. Again, it works fine for diamond angle grinder / chop saw blades too. Go figure huh? regular old wd40 beating out the aluminum product of choice... but again this is for diamonds and high speeds, NOT tapping. I use alumitap for aluminum tapping.

For aluminum die grinding I use the alumicut large flute burr with wd40, and for aluminum milling I use a 3 flute non ferrous metal carbide alcro endmill with again..wd40. wd40 smells alot better then tap magic too (what is in that, menthol derivatives? )

I think you should stick with oil and get a wash cabinet to clean up the metal after machining. You will also get less dust if you use a coolant, which is good for your lungs. I don't think spraying alcohol is a good idea, it has a low flash point compared to normal oils. I would say that its actually a really bad idea. Your work piece is gigantic plate, cover that with alcohol and its like a truck fire. Alcohol is fine for small shop use probobly.. but not for a giant plate machining operation. You are talking 6x4 meters, thats 18x12 feet. That would make a hell of a fire.

All it would take is a inclusion into the aluminum sheet to spark against the endmill and light it up. Or maybe a diamond from the endmill getting separated from the endmill, lodging into the sheet, and then being sparked by the next diamond in line (sinter fail).

[langwadt]

alcohol doesn't stink and leave the parts/chips an oily mess, and it's not flood coolant it is a minimal drip feed

[cepsbow]

GREASE.  You need to dip the bit in a good tube of heady duty grease, it will cut through the aluminum like butter after that. Make sure to keep a good even coating around the bit. A dispenser would probably cut on downtime.

[BrokenYugo]

I take it you've tried all imaginable speeds and feeds before resorting to diamond tooling?

GREASE.  You need to dip the bit in a good tube of heady duty grease, it will cut through the aluminum like butter after that. Make sure to keep a good even coating around the bit. A dispenser would probably cut on downtime.

There are also some paste type cutting oils/compounds available, either way I'd try brushing it along the toolpath.