Practical CNC – how to deal with drilling 2mm holes in Aluminium

[Steve WithnellParticipant @stevewithnell34426]

[Steve WithnellParticipant @stevewithnell34426]

I've been thinking about buying one of those KX1's for a while now and have a couple of projects where I thought they would be great.

One of them involves drilling a lot of accurately placed 2mm holes, 10mm deep into 6062 aluminium. When I started doing this manually, the aluminium kept sticking to the drill bit, so every hole had to start by cleaning the flutes of the drill and unsticking bits of aluminium, then brushing with a bit of parafin as a cutting fluid. Drilling manually, it's possible to feel the drill getting clogged up.

Struck me, that with a little CNC, this would be a problem and rule out using a CNC. I must be doing something wrong somewhere as that manual process isn't happening on production shops!

The spindle was running at 2000rpm or thereabouts.

Steve

Edited By Steve Withnell on 10/04/2017 21:59:26

[John HaineParticipant @johnhaine32865]

Hi Steve, I had occasion to drill a ring of 60 1mm holes in a scrap hard disc which is basically aluminium though not sure what grade. Admittedly it was only 1mm thick, but I ran the mill at max revs, about 5000 rpm and used a peck drilling cycle with probably a 0.5 mm peck or less. No lube, didn't have to clear the flutes, no drama, no broken drill.

[EmgeeParticipant @emgee]

Steve

I have a cnc mill with a max spindle speed of 2000 so can imagine the problem you are experiencing, you need to keep lubricated and blow or wash away the swarf and peck drill which should keep your problems to a minimum. I dril 2.8mm holes 25mm depth in cast ally using the same method.

Emgee

[Anonymous]

There is no problem drilling aluminium using a CNC mill. I'd use a full peck cycle, ie, the drill is completely retracted each peck to clear the swarf rather than to just break the chip. For a 2mm drill a 2.5mm peck would be ok, and has the advantage it is an integer divisor of 10. If you're not careful with peck distance versus hole depth you end up a with a very small final peck which wastes time and can start to blunt the drill. I'd be running at 3000+rpm and a feedrate of around 150mm/min.

Oh, and flood coolant is essential to prevent the swarf sticking to the drill.

Andrew

Postscript: Despite the slightly disparaging comment on another thread I use 4-facet drills, so I don't need to faff around with centre drilling first.

Edited By Andrew Johnston on 10/04/2017 23:14:25

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