Proper drills/coating for aluminum?

[StrikerDown]

It seems to me I have read somewhere that titanium nitride (TiN) coatings don't work well in aluminum?

Drilling close to 20 inches aluminum yesterday with HSS TiN coated bits I notice the surface of the bits seem to hold onto the aluminum and in some cases I have been getting BUE to the point of plugging the flutes.

Is there better way?
lubrication, Coolant, or just buy uncoated HSS, cobalt or carbide bits.

Cobalt or carbide seems like overkill for aluminum unless it works fine in this and steel/harder steels and SS making it more versatile (one drill set instead of two).

I haven't worked Titanium yet but don't want to rule it out, considering it's popularity in this hobby!

You guys have probably covered this, but I can't find where. I you have, point me and I will look!

 

[Torque1st]

Kerosene in a squirt can. WD-40 $$$ will also work as a cutting fluid for aluminum.

 

[wykeite]

+1 on kerosene, white spirit also seems pretty good. The main problem is that unless you buy specialised drill bits the off the shelf variety have the rake angle optimised for steel. This is too little for aluminum and causes the build up that is notorious. Unless you're prepared to shell out for the specialised bits stick to regular HSS. Also try 'peck' drilling.

 

[LukeA]

Also try 'peck' drilling.

Yes, break the chip.

I use motor oil.

 

[StrikerDown]

As always you guys came through! My current project has a lot more drilling and tapping ahead.

KEROSENE... The problem with getting old is CRS disease (Can't Remember Sh..!)

I do a peck cycle, not sure what the correct procedure for it is , but I try to cycle when I think the it looks like the chips are long enough to not just fall back into the hole but rather come out with the bit?

Thanks so much! lovecpf

 

[Russel]

As always you guys came through! My current project has a lot more drilling and tapping ahead.

KEROSENE... The problem with getting old is CRS disease (Can't Remember Sh..!)

I do a peck cycle, not sure what the correct procedure for it is , but I try to cycle when I think the it looks like the chips are long enough to not just fall back into the hole but rather come out with the bit?

Thanks so much! lovecpf

What I do, when I have the patience, is to drill 2 diameters deep on the first bite then 1 diameter at a time after that, withdrawing the drill bit completely between "pecks" and clearing chips from it with a cheap paintbrush.

 

[StrikerDown]

What I do, when I have the patience, is to drill 2 diameters deep on the first bite then 1 diameter at a time after that, withdrawing the drill bit completely between "pecks" and clearing chips from it with a cheap paintbrush.

That is pretty much what I do, guess I'm not too far off. Now to add squirt of kerosene.

 

[Russel]

Oops! forgot the Kerosene! I actually use "aluminum cutting fluid", basically the same thing as kerosene.

 

[precisionworks]

Precision Twist has two drills on the recommended list for aluminum (although I have tried neither one):

PHP3F/PHP3M for up to 5D deep

R570 (CDX-DH) for up to 8D deep

Their telephone tech support is awesome, and you can decide if the increased performance is worth the added price.

 

[Torque1st]

Aluminum cutting fluid = Kerosene + $$

 

[gadget_lover]

Aluminum cutting fluid = Kerosene + $$

While that is quite true, I must say I sort of like the smell of Tap Magic Gold, even as it smokes. I'm not so fond of the smell of hot kerosene.

Daniel

 

[Torque1st]

While that is quite true, I must say I sort of like the smell of Tap Magic Gold, even as it smokes. I'm not so fond of the smell of hot kerosene.

Daniel

I know what you mean there. I try not to breath hydrocarbon fumes of any kind tho. With advancing age they seem to make me ill. It seems they are hard on the old liver.

 

[SRT Mike]

TiN coatings are good for aluminum, they are more "slippery" than uncoated. TiCN and TiALN are OK too - not specifically good for Aluminum but not bad.

Black oxide is the one that's not good for aluminum.

Regular bright finish drills are good too. I drill a lot of aluminum - you can get a better finish with drills that have a custom profile ground on the points, but those are hard to find and only really worth it if you have a project where you are drilling a LOT of aluminum.

With a regular bright finish (or TiN coated) drill, the trick to nice holes is a rigid setup, plenty of coolant or cutting fluid, use peck drilling for holes greater in depth than the drill is in diameter (i.e. deeper than a 1/4" hole for a 1/4" drill, peck drill it). Check with the manufacturer for feeds and speeds for the thickness and alloy you are cutting, but with rigid setup, peck drilling, and coolant, you should be pretty much OK. 5,000 RPM with 10ipm feed rate wouldn't be a bad starting point if you're doing 1/8"-1/4" holes. That's very rough, you'd be better to check feed/speed for your drill size, but you don't want to be way off those numbers (like 500rpm and 50ipm or something).

 

[precisionworks]

I sort of like the smell of Tap Magic Gold

I use TMG for all steel drill & tap jobs, and Tap Magic Aluminum for aluminum, brass, anything soft or nonferrous.

The MSDS lists the components as:

Petroleum Distillate (Aliphatic 90%/Aromatic 10%) at up to 60%
Methyl Laurate at up to 40%
Essential Vegetable Oil at up to 10%

http://www.tapmagic.com/TMalum.pdf

 

[PhotonFanatic]

Relton A-9.

 

[PEU]

Aluminum cutting fluid = Kerosene + $$

You forgot the last item in the formula:


Aluminum cutting fluid = Kerosene + $$ - less smell

 

[StrikerDown]

Thanks, the kerosene does a fine job, They actually cleaned up the dril bit some and for the most part the flutes stopped clogging up, started using a little shorter peck cycle too, it all helped.

Thanks again. lovecpf

 

[Torque1st]

I am glad the kerosene helped you. That aluminum welded to the drill flutes can be removed by pressing it against a block of hard wood or a quick drill into some steel. We used kerosene in production because it worked well and was a lot cheaper than the more exotic substances.

Once you get used to using a drill bit you can tell when to back off and start again in many materials by watching the chips. Warning- There are some materials that work harden and if you back off the pressure for a moment that can be as far as you get sometimes.

When you have a lot of aluminum to drill and some experience you can learn how to modify a standard twist drill to work better in aluminum.

 

[wquiles]

When you have a lot of aluminum to drill and some experience you can learn how to modify a standard twist drill to work better in aluminum.

Thanks to feedback here and in one of the yahoo groups, I got some new, USA made, 135Deg, Split Point, Machine Screw length, TiN coated Cobalt drills while MSC had a special (so these were very affordable!), but as I am not afraid of asking stupid questions, I will bite: how do you modify a standard twist drill to work better in Al?

Will

 

[Torque1st]

-Ahh, open the machinery handbook and regrind the tip... Reduce the relief angle and reduce the rake formed by the flute spiral. You will get adept at sharpening your drill bits for specific applications. Take a look at the forms for regular HSS or cemented carbide lathe bits and remember that things like milling cutters or drill bits are just miniature curved lathe bits. The same principles apply.

The Machinery's Handbook is your friend. The old South Bend lathe manual is also a good reference. There are also good college level textbooks on metalworking available.