Advice needed. Aluminum + Drilling

[TECNC]

Hi Guys,

Im looking for some advice on dropping that 10mm drill bit all the way through this work. Cutter is 200mm long and material is 195mm high.

I ran a drilling path on it and bit tip its jumping and making some horrific chattering.

I am new to metal machining so this is all new to me.

any advice is greatly received

Regards Tom

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[deadlykitten]

hy Tecnc / long holes require a setup that is able to deliver cilindricity characteristics as good as possible

i would recomand attacking the part not with the longest drill, but with a pallete of tools

short + intermediary + long tool; the longest the tool, the lower the specs, and viceversa

maybe 2 intermediaries ? i have to check common lenghts for the o10 drill, so to make a better recomandation

"short & intermediary" should be carbide long tool should be hss

what do you think ? kindly

[coherent]

If you have a high speed spindle it's a bit harder to use standard drill bits to drill it, but slow down the rpm if you can. Smaller diameter bits will overheat quickly at high rpm and gum up the bit quickly causing chatter and noise. If you aren't already, you should be peck drilling it with full retract between pecks and using a lubricant. Keep the peck depth fairly shallow and slow down the plunge speed if you're still getting chatter or noise.

[A_Camera]

Hi Guys,

Im looking for some advice on dropping that 10mm drill bit all the way through this work. Cutter is 200mm long and material is 195mm high.

I ran a drilling path on it and bit tip its jumping and making some horrific chattering.

I am new to metal machining so this is all new to me.

any advice is greatly received

Regards Tom

That drill bit certainly doesn't look like 10mm in diameter, but I can be wrong... It is however looking VEEEEERY long. I don't know what sort of aluminium that is and if your spindle is high speed or not, but here is what I think... forget about it. I would just mark the holes using a MUCH shorter 90 degree drill bit and would use a pilar or bench drill to drill the holes. I do drill aluminium on my CNC, but the widest drill bit I ever used was 6mm and the longest hole was 16mm deep using 5000 rpm, peck drilling with full retract and 0.5mm Z advance. This gets through, but if do it differently the drill gets stuck in the hole. Mind you, I don't use any lubricant, so I could probably go deeper if I was using lubricant as you seem to do, but I would still not hope for the depth you are trying to do. Also, I am not an expert so maybe there are other ways to do it as well, but it works for me.

[jwatte]

peck drilling with full retract and 0.5mm Z advance

That seems way too conservative. Generally, I have good success with first peck being 3x diameter, and successive being 1.5x.
(I've seen 4x/2x as the recommendation from other sources, although that may depends on how many pecks you're taking.)

I typically spin a drill at 3000 rpm, and then feed it at 100x diameter, per minute. So, for a 6mm drill, I'd feed at 600 mm/min, and take the first peck at 18mm, and successive pecks at 9.5mm. Retract to one diameter (+6mm) above the surface.
Also super important is to make sure there's coolant/lubricant/cutting fluid in there. You might even want to get some ester based cutting fluid and squirt it manually (tapmatic or somesuch.)
Also, if tolerances are important, you'll want to pre-drill at a narrower size, and then ream it to specified dimension. You definitely want the cutting fluid there!

[deadlykitten]

hello again i don't know if Tom will get back on this thread(*), but i just remembered high pressure system coolant through : this should help delivering better cilindricity, by evacuating chips more easy and by making the peck distance more stable, or why not, even longer ( or even no peck at all )

benefits of a high pressure system are known ...

i would like to say that is possible to add such a system to a machine that does not has it, by using somekind of a low cost solution, like the idea behind reCool from RegoFix / kindly


(* maybe he met the cat of his dreams, and now they are happy in a nice sunny spot )