Final Finish in Aluminium

[Joe Lavery]

Hi all,

For many years I was unable to cut aluminium on my home CNC; (Zenbot 600 x 400 with a Kress 1050 Router). I either snapped the bit or ruined the stock.

However a week ago I saw a user on YouTube with a similar setup to me, who managed to cut 5mm thick aluminium by using .1mm depth of cut and a speed of 800mm min with his router set for 8000 rpm. So i though why not give it a go, I've always cut with far more aggressive settings, with feeds and speeds much higher, (which is obviously why I kept breaking cutters.).

Anyway it worked perfectly, well nearly! The cut was clean and neither the cutter or the router were even warm. My only complaint was on close inspection the edge of the material had regular vertical lines, roughly .5mm apart, as though the cutter was juddering.
This was using a single flute 3mm carbide cutter as the speeds and feeds above. Incidentally i don't see this effect when cutting wood, even hardwood or Birch ply which machine very clean indeed.

I'm not sure whether I should slow the router speed of increase it, or slow the feed or increase it?

Any though or advice would be appreciated.

Joe.

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[dazp1976]

On the Seig X2 with a 6mm 3 flute cutter (limited with rpm) finishing around the edge I run 1600rpm taking 0.2mm off at 150mm/min. Comes out smooth.
Working it out to 8000rpm it looks like it's equivelent to 750mm/min.
Maybe for a 1 flute divide it by 3? so 250mm/min?

What flute count were they using?

[CL_MotoTech]

Try leaving some stock, something like .001", and then doing a full depth pass to clean up that remaining stock. I am not familiar with machines as small as yours though, so you may want to work up to that. Even if you do three passes to clean it up you should get a nicer finished than with all those step downs.

[Joe Lavery]

It was a single flute, using the speeds and feeds I mentioned. But running a final pass to clean up the edge sounds a good option.

Thanks for your reply.

[Joe Lavery]

Like the previous member Taking a final fine cut looks like a good option. I'll give it a go and see how I get on.

Thanks for your reply.

[doogle]

I don't have much experience working with aluminium with my router, but one thing I've noticed is that chip recutting can massively affect the finish.

What kind of coolant/lubricant are you using (if any)? Are you doing anything to evacuate chips? You should be able to hear an extra crunch if the cutter is having to go through chips... Maybe just clearing the path ahead of the spindle with a brush should help a bit. (As well as what others have suggested).