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Drilling Aluminum.

B

bartsimsonii

Gawd
Joined
Dec 27, 2005
Messages
831
I have 2 sheets of 3001 aluminum and everytime I drill a hole a little cylinder forms in the back. What can I do to stop this?
 
Try placing your sheet of aluminum on a wooden block
keep it nice and tight on the lower surface, then drill

your drill bit might not be sharp enough for aluminum
and is pushing through instead of cutting through
 
Bits might be dull, try using a wood block template, If not, get new bits, use tape and a wood block (that'll help extra)
 
This is what I call "Punching Out" But I know there's a real term for it.

The wooden (or as I like to use perspex, cuz I have alot of it) block technique really does help things.

Also, use a higher RPM drill if you can, and use less pressure. Alu is such a soft metal that the weight of the drill should be enough.
 
I have already done the wooden block thing and am using a drill press. I am 99% sure its the bit.
 
Aluminum is a "soft" metal, as opposed to Stainless Steel, which is "hard". When drilling aluminum, it is best to drill with slower RPM's and less pressure. You can actually melt the aluminum with high RPM's, because the heat will build up. Especially in thicker pieces. You'll see little globs form on the walls of your hole and globs attach to the flutes of your bit if this happens.

You will likely never get a perfect edge with just a bit. One option is to do a little countersink trick. This works especially well on a drill press where you have a lot more control.

If you drilled a 1/4" hole. Use a 1/2" bit and just barely hit the metal with it. Practice on a piece of scrap first. If you do it just so, you'll be left with a 1/4" hole with a nice little beveled edge. There are actually tools made especially for this.

http://www.leevalley.com/wood/page.aspx?c=2&p=41012&cat=1,180,42240,42281&ap=1
 
I have extensive metalworking experience and may be able to elaborate on what has already been suggested.

- Always use a sharp bit
A dull bit will require more pressure which makes more heat

- Lubrication/Coolant
Use a lighter cutting oil than you would on steel

- Proper RPMs
Remember, the larger the diameter the drill bit, the slower the RPMs required. Watch the chips coming off the bit. That is your key to what is going on. If they are turning blue you are creating way too much heat. Either slow the RPMs, the pressure, use more cutting oil ... or all of the above.

- Drill pilot holes first
Let's say you want to drill out a 1/2" dia hole. Start with 1/8" then work your way up to 1/2" in two or three steps.

Hope that helps ... best of luck.
 
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