Strange Melting Aluminum with Endmill

[mgb1974]

I am cutting a piece of 6061 Alum. with a 3/8 carbide ball endmill. I am Feeding at 10.6 in/min and a rpm around 1k. I am not sure on rpm becuase the machine is a converted bed mill and it does not have a read out. Turning the endmill CW and cutting at about .25 depth of cut.

It is literally melting the alum instead of making chips. I have never seen this before this bad. I tried slowing the spindle down and messing with the feeds but no differance. The endmill was gummed up though at that point.

What do you guys think??

Thanks!

[BSawyer486]

Dont use TIN coated tooling on aluminum. The aluminum has a tendency to bond to the coating. Also try to lubricate with alcohol or WD-40. and you should be able to get around the problem.
Bruce

[Geof]

Your speed is slow, very slow especially for the feed you are using. It is likely that chips simply jammed in the flutes so you were rubbing aluminum against aluminum.

How fast can you machine run? Ideally you should be doing several thousand rpm and be using coolant. If you cannot go faster than 1000 rpm reduce both you feed and depth of cut and make sure you have coolant or lubricant.

Part of the problem with ball mills is that they have to cut all the way round the ball but this means the cut is getting closer and closer to the centerline so the peripheral speed gets lower. Right at the center the tool is pushing the metal aside rather than cutting it. Coupled to this is almost non-existent chip clearance.

[mgb1974]

Thanks for the help.

The machine should go to 4200RPM. Problem is its a dial turn to adjust the rpm and for some reason its is all screwed up with the scale.

Try max it out and using some wd-40.

[DMF_TomB]

i would try oil or some other cutting fluid. aluminum is well known for sticking to cutters when no oil is used.

be careful of alcohol or wd-40. some things will burn at room temp and some thing burn when hot.

I was heat treating a 1.5" dia tap and used sulphur based cutting oil from a pipe machine. The red hot tap caused the oil to get hot , so hot it kept burning with tap out of the oil.

The fumes from wd-40 and other "coolants" can and have made me sick before. By the way I dumped the burning oil into the pipe machine and turned the coolant on. The cool oil mixed with hot oil and it stopped burning. But I was smelling the fumes for a week.

Like kerosene and gasoline. gasoline will ignite if a match is used. kerosene will do the same thing if it is hot enough. Just make sure if you have your machine on fire you have a way of putting the fire out.