Slotting (milling) aluminum - the answer

Not if you specify a T6 condition. That machines quite well, but requires adequate lubrication while machining.

You'd also enjoy machining 2024 aluminum, but it, too, just like 7075 and

6061, should be in a heat treated condition. Any of the soft condition aluminums don't machine nearly as well as the artificially aged materials do. Seek a T351, T4, T6, or higher condition and you'll have good luck with any of them.

Be advised that 6061 is the only material from this group that can be welded, and if it is, it loses the aged condition. It can be restored after a solution heat treat, than aging once again.

Harold.

I machine 6061 all the time, with no problem. I have even had to anneal 6061 for bending, and then machine after the bend. If you think you can plow a slot the width of the end mill and leave it like that, it won't work. You have to mill the slot right down the middle with a smaller end mill, then make cleanup passes down both sides. The end mill wanders due to the cutting forces, leaving a wavy wall. If the material is thick, you need to mill it quickly in several passes of successively greater depth until you break through, then do the cleanup passes.

Jon

What works even better than running the endmill right down the center is to bias it a little towards the climb cut side. The conventional cut side of the slot is the side most likely to have the cutter dig in and ruin the finish. This is because the cutter is being pushed away from the climb cut side. ERS

Tried that one too - to no avail. My application requires milling hundreds of slots (going metric for a sec): 50 to 12 mm longs, 6 to 2mm wide. Doing it in a single pass-per-slot is the best way to go.

Working with 7xxx allows plunge cut through 1/8 of material and then moving the mill table to cut around perimiter. 2-flute endmills work the best I found, 4fl get clogged up. I do use cutting oil.

Of course when using 1/16" end mill you can not crank up the feed handle, have to do it in .002-0.004 micro-steps. However with 1/8 endmill you can feed as fast as you can crank it

Huh?

6000 series Al slots just fine. You take about 0.005 inches vertical per pass. You don't hog full depth.

The clearance on the end tooth is better than the side tooth, you see, so the metal doesn't stick.

I tolerance everything and tolerate everyone. I love: Dona, Jeff, Kim, Kimmie, Mom, Neelix, Tasha, and Teri, alphabetically. I drive: A double-step Thunderbolt with 657% range. I fight terrorism by: Using less gasoline.

Actually if you just set it and run it expecting perfection full depth, what happens is the cutter and work both deflect such that the climb side is tight and the conventional side loose. This is caused by the more or less massive cut forces right at center, and cutter rotation. The cut is deepest at center.

I know this because I mill on a cross vise with *no feed screws* frequently, and have explored the feel of the cutter deflection both by opposing deflection with my hand and by setting the gibs to lock with various friction settings. For me this is true pleasure, and if I had a ball way cross vise with locks, I'd be even happier exploring this relationship, looking for the stable path between success and chaos.

It's like a freakin' tent revival. Pre-feedscrew milling technology. Ancient knowledge.

I tolerance everything and tolerate everyone. I love: Dona, Jeff, Kim, Kimmie, Mom, Neelix, Tasha, and Teri, alphabetically. I drive: A double-step Thunderbolt with 657% range. I fight terrorism by: Using less gasoline.

Well there's still a motor driving the spindle. In *most* cases.

Jim

Which cutting oil? Try the citrus based stuff.

Ted