A wood guy trying to cut aluminum

by Fubarius

So I run a few CNC wood routers at work, making store displays. Particle board and MDF mostly. But today we got a new project than needs a little machine work on some aluminum sliding door track. Just a little light pocketing, but in a cramped spot so we have to use tiny 1/8" bits. Those little buggers are a pain, so of course I'm having trouble finding the right feed and speed rates.

If this was wood I'd be at 18,000 RPM, 150-200 inch/minute, and taking around 1/16" per pass. Compare that to our regular production parts with our good 1/2" compression spiral carbide bits which we'd run at 18,000 RPM, 600-700 inch/minute, on a full depth pass on 3/4" material.

Now our machines are rated for non-ferrous, we just haven't done anything with aluminum other than cutting MDF boards with an aluminum veneer on them. With what little I knew about cutting aluminum I knew I'd have to slow things down. First I tried what I though was slow, 15,000 RPM, 120 inch/minute, 1/16" cut... and broke the bit right off.

After a few more test pieces, and ruining a second bit (chips clogged the cutter on that one), I found some settings that seemed to work for now. 10,000 RPM, a mere 20 inch/minute (didn't even know the machine would go that slow), and 1/32" per pass. This gave an adequate finish, but still doesn't seem quite right. Plus the part run time felt unbearably long, but that could be just in comparison to what we're used to since most simple jobs like this in wood take just seconds per part.

So, any suggestions? Any ideas on speeding up the run time (my boss would appreciate it)?

The aluminum is a pretty cheep extruded door track, not sure what grade. The bits we're currently using a 1/8" 2 flute straight router bits, made by Bosch if I remember correctly.
David Johnson
AKA Fubarius

Posted on Jun 13, 2017, 1:35 PM

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  1. 10,000 RPMs still seems fast. James, Jun 13, 2017
    1. Vortex is the place to go. Fubarius, Jun 13, 2017
  2. Can you add lubricant or air?. MarkT, Jun 13, 2017
    1. Might be able to do a little air, but liquid coolant isn't going to happen.. Fubarius, Jun 13, 2017
  3. yeah - need coolant. ydna-zds, Jun 13, 2017
  4. Here's an example of a very similar machine to what we're using.... Fubarius, Jun 13, 2017
  5. your cutting speed.... sniper1rfa, Jun 13, 2017
    1. oh, and if you switch to 3-flute endmills.... sniper1rfa, Jun 13, 2017
      1. Unit of measurement changes sure are a headache, and probably part of the issue.. Fubarius, Jun 13, 2017
  6. cutting aluminium.... Snowtroll, Jun 14, 2017
  7. Pardon a bit of a sidebar. Robert L Martin, Jun 14, 2017
    1. Not a concern. Russ Kepler, Jun 14, 2017
      1. Termite is VERY dependent on particle sizes.. Z-man51, Jun 14, 2017
    2. Extremely unlikely. Sniper1rfa, Jun 14, 2017
    3. Aluminum and Steel is bad, but Wood and Steel can be worse. Fubarius, Jun 14, 2017
      1. Dust explosions are NOT FUN!!!. Z-man51, Jun 14, 2017
        1. Unfortunately a regular occurrence in the Corn Belt. Dave H, Jun 15, 2017
          1. Bigger fun with coffee creamer!. Salda007, Jun 15, 2017
            1. They did it wrong.... Snowtroll, Jun 16, 2017
              1. Re: They did it wrong.... Dave H, Jun 16, 2017


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