Ok finally got my little CNC Mill working and decided to chop some aluminum. Loaded up 0.5' HSS Tin coated 4 flutes and spooled it to 2000 @ 15IPM. DOC was 0.1'. I was cutting a circular pocket. In about a minute of operation I noticed deterioration in quality of the finish. Looked at the endmill and its tip had chunks of aluminum clogging it.

Tried 0.25' HSS 4 flutes endmill @3500 and 15IPM pocketing. Same thing, chips clog the endmill.

No coolant.

I calculated based on 220-260 SF speed and 0.001-0.002 load per flute.

What am I doing wrong?

zaebis
Actually, you answered your own question "No coolant."

If you don't have something to flush the chips out, they will clog up the flutes, heat up and melt. It is mandatory to remove the chips and also, you do not want to re-cut them.

I personally tend to use 2 flute mills as this also give more room for the chips.

TiN coating is not the best thing for aluminum. It tends to gall. Plus you are not really running at higher RPMs and feeds. I would defeinitely use coolant if possible. If not, use some of higher helix angle endmills designed for aluminum. You also don't state what type of aluminum you are cutting and that can also add problems to chip welding.

Yes the chips were just piling up inside the pocket. Especially bad for long, deep and narrow pockets. I will try to suck the chips away with a vacuum and add some WD40 as a coolant/lubricant surrogate. Will also switch to 2 flutes. It is 6061.

Do chips stick better to HSS than carbide uncoated? Or under the circumstances it would not matter?

wd-40 spray is a little too thin and the fumes are not the best thing to inhale.. try 30 weight oil or a medium weight oil. if nothing else the oil residue will keep things from rusting even if most of it wiped up. Way oil which is a sticker type of oil and less likely to fly so far but the globs of oil and chips may not fall away fast enough.

i usually just use a plastic sqeeze bottle of regular medium weight oil and apply some to the area being milled. i use a compressed air gun to help blow the chips away, see what's happening, keep things cooler and of course blow the oil fumes away from me. i hope your shop has some sort of air ventilation.

disposable rubber gloves and air ventilation i consider important. i use throw away gloves so my computer keyboard does not get oily. oh try not to get oil mist and chips on computer stuff.

Try using just an air blast to keep the chips out. Oil is OK but a soluble or water base(synthetic coolant) seems to work better to keep things "cool".

If you are recutting chips and packing them in they have no place to go. A few chips start to drag, create heat and you gall the mill and part. It then just generates heat and does nothing. This is for any endmill (HSS, carbide, cobalt, etc.). the simplest thing you cna do right now at a minimum is vacuum. Then vacuum with a little coolant. Make sure you vacuum cna handle the wet stuff. You don't want a wet festering vacuum.

Use a 3 flute endmill, they work amazingly well compared to a 2 flute.

WD-40 works well. A9 works well. Just get some lube in there.

Try using a Data Flute. I believe it's called an AFI end mill for aluminum. Works great and will get tons of life out of tool.

Oil is a lubricant and not intended to be used as a cutting fluid. Cutting oil is way different then way lube or motor oil. Too much viscosity can cause more harm than good. I'd try using straight water soluable oil with out the water and fewer flutes on the tool to give more chip clearence. But you will need some type of coolent on Aluminum.

i am a plant manager of well known company in florida and if you are interested i will get you some sample aluminum cutters to try. we have had great luck in high speed maching and general application.

My experience has shown that the best way to prevent aluminum from clogging up the flutes of an end mill is to use mist coolant. I bought a Noga Mini-Cool and use Kool-Mist Formula 77 concentrated coolant 4oz per gallon of water. It makes a huge difference. Both can be purchased from Enco.

what I use for my personal use at home is the pipe tapping fluid they sell at home depot (in the pipe section) , it's about 10 dollars for a large bottle , a paint brush of it on a part goes a long way

I use 3 flute carbide end mills for aluminum. these have worked great for me really long tool life, and flooding with coolant.

i use regular oil as a cutting fluid for decades and it works good for me.

1) i got tired of rusty, dirty machines with dry cutting fluid gunk all over them

2) i got tired of not being able to read the dials and scales from dried residue from cutting fluids

3) i like my machines lightly oiled at all times

aluminum sticks to cutters when it gets hot and a false cutting edge sticks to the cutting edge which makes it act as a dull cutter. try a little plastic sqeeze bottle with 30 weight oil or air tool oil and apply a little to the aluminum. works for me and i have used it for decades with no problems unless you call after blowing chips off the machine it is left clean, dials and scales still readable and machine left lightly oiled a problem

I avoid 4 flute endmills like the plague with aluminum.

You also didn't say what "flavour" of aluminum you're using. 6061 gums up easy. If you're plunging in and cutting pockets makes sure you use some cutting fluid. You don't need much. Just a quick brush of any good aluminum fluid should do the trick. Get yourself a mister too. Kool-Mist is super cheap, make sure you have good ventilation.

Warren

I have always used WD-40 on 6061 Al. when machining on The manual equipment. Some guys like It, some are discusted by the smokes smell. I'm sure it's very toxic, ventillation is a must. You wouldn't believe how nice of a surface finish you can get , especially with hand ground HSS and Cobalt form tools on the lathe! Kool mist works great, but the smell and effects to my sinuses keep me from turning it on very often.