Machining aluminum composite

[cnc_fabricator11]

Hey everyone,

I'm having some issues with tooling marks when pocketing into aluminum composite. I'm using an Onsrud 66-315 which is designated as a bottom surfacing bit, but still having issues with tooling marks on the polyethylene core. I was wondering if anyone might have suggestions for achieving a smoother surface.


Thanks

[Brady Watson]

I'm seeing a very small step or ridge in between the passes, indicating that your Z axis may not be perfectly square to the table/bed. You can try to 'read the lines' and apply some 'English' to the spindle to knock it back into square using a rubber mallet with careful and deliberate taps. Otherwise, you have to pull the spindle, make sure adapter plate is completely parallel with the spindle (and check it as you tighten up the bolts) and then use a good square to square the body of the spindle to the bed of the machine.

In terms of the swirls, there's not a whole lot you can do about that other than truing up the Z. If you have ever seen aluminum milled, there are tool marks as well on $100k CNCs when pocketing...The denser the material, the more you will see the swirls 'telegraph' on the material. You can try a regular 2-flute center cutting end mill (HSS and carbide) to see if that clears it up some for you.

-B

[knight_toolworks]

At least that is clean. I had to do this sheet of parts 400 little signs pocketing out the letters and the test was fine first sheet ok second sheet I had tons of fuzz and the centers of the letters were popping off. all toolpaths were the same same bits but new. I think the sheets can vary on how they cut.

[frank134]

Pat I used the 66-300 and the bottom came out nice and clean. I could hardly beleive it . It almost look like a mirror finish. I cut in the material about 1/2" in 1/8" step.

[cnc_fabricator11]

Thanks for the input everyone. I'll tinker with our spindle a bit to see if I can eliminate the ridges and I'll look further into other bits in the 66-300 series.