Hey guys, I've got a quick question for you regarding milling aluminum. I'm wondering if it is ok to machine aluminum with no coolant, keeping high-pressure airflow on the cutting bit instead. I understand the need for coolant to keep the bit and stock clear of debris and to prevent overheating, and the few runs I have made with the air seem to work fine. I suppose I was just wondering if there is any other considerations that would lend itself to using coolant over air. As I’m sure this is critical, I’ll be machining almost exclusively aluminum and other soft metals, generally at a low feed rate (2-6in/min) and at relatively low rpm’s (1500rpm). Thanks.

So long as you don't take too heavy a cut you should be fine. Keep the air going on it.

Excellent...I forgot to mention, I'm using HSS bits no larger than 1/2", and yeah, the cuts I am making are no deeper than .05" at a time, so very little material is being cut each pass.

Yes, you can machine aluminum dry. I machine aluminum molds and do all my rough and semi-finish passes dry. When I do dry machining I run an air line from a solenoid to the coolant tube of my machining centers (Fadal) and plug the solenoid cord in place of the coolant pump. All I use is shop air pressure to blow the chips off.

Large/deep pockets and cavities are prime candidates for dry machining. Coolant quickly turns them into swimming pools and the chips can no longer evacuate from them, leaving you with aluminum chip soup. Now your tool starts to recut the chips.

Dry machining is cleaner and brings the cost of using coolant down but there are times when you should still use coolant, drilling and tapping for example. I still do my finish passes with coolant.

My speeds vary between 7000-10,000 rpm and feed rates from 100 - 350 ipm depending on the tool, but dry machining works just as well on slower/manual machines as you found yourself. I spent the first 12 years of my career cutting aluminum and steel on a Tree tool & die mill that had no coolant provision, except for the manual spray bottle and brush method.

Good deal, I figured it would probably be alright, just wanted to check with the pro's first :) . Alright, I'm off to try and mount this air line somewhere on my machine, thanks again. :cool:

I would only caution on what material type it is. I have found no problem dry machining 6061, and 7075, but 3003 I have always had to run coolant because of the "gumminess" of the material. It likes to gall cutters up in a heartbeat. Just some of my past experience.

I would only caution on what material type it is. I have found no problem dry machining 6061, and 7075, but 3003 I have always had to run coolant because of the "gumminess" of the material. It likes to gall cutters up in a heartbeat. Just some of my past experience.
6060 common garden variety exhibits the same behaviour, I lost a flute on an 8mm end mill recently when the coolant pipe ran off the side of the job during a pass!

At the least give it a spray with WD40 or CRC56 while cutting :)
Your cutters may thanks you.