Newbie- Machining Aluminum with tight tolerances

[stuby]

Well, it may sound silly but all Ive turned in my Leadwell LTC-15 is stainless steel and tool steels with moderate tolerances (.005). I havent done any 6061 aluminum yet, and I am wondering what kind of tooling I should use. I was told to use High Speed Steel to turn it, for a nicer finish. The part im making has a .0004 tolerance, so I could use some help as far as speeds and feeds go as well. Like I said before, no experience on this type of material, let alone with such a small tolerance. Am I headed in the right direction with the HSS on this or not? Anything to set me straight would be appreciated. Thanks.

[Geof]

You can use uncoated carbide and it is possible to get inserts with a grind specially for getting a good finish on aluminum.

Your tolerance is tight for aluminum. Linear expansion per unit length per Deg F. for aluminum is 0.000012 so you really need a temperature specified for doing the measurement.

[cam1]

I use CCDT and DCGT syle inserts (uncoated carbide). They work extremely well on aluminium (and for the odd short run stainless job). They are designed to "scoop" the material.

regards

[SRT Mike]

I use solid carbide positive rake inserts. They are made for aluminum. Aluminum is soft and a non-sharp tool tends to push it rather than really cut it, and chip control can be a PITA, but the positive inserts help.