[Steven Smith]

Could you give a little more information on what you are currently doing? What bits, what is your hold-down strategy, coolant/chipclearing, what thickness and grade of aluminum, etc.

We struggled for a while to get our gantry mill to cut aluminum properly. We're currently running a 3/16" Amana single flute bit at ~50IPM and 12000 RPM (need a true spindle to run lower with power, not a router). We have a high pressure air blast that is sufficient when cutting 6061 (easiest to cut IMO) and we use a little WD40 (need to convert to a better fluid) when cutting 5052, which we use for bent parts. We can do ~0.0625 on our DOC without major issues.

We lay out our entire stock and pieces in our CAM software, and then pre-mark drilling patterns between the parts. We use wood screws on the edge to hold down the piece, then have the gantry drill its own holes in the middle of, and around every piece we are cutting out. In a ~2'x2' work area, we might end up using 20-30 screws. If you don't have your workpiece held down really well, it will vibrate against your cutter though, creating heat. A better way might be a vacuum table... but hey... we have freshmen.

One last note, you need to make sure your sacrificial bed is well leveled (flat in the Z). If you have wildly varying DOC issues due to an unlevel bed, that can eat a bit up in a hurry.