Recommendations for Drilling 99% pure aluminum

[JeremyV]

Hi, we've been trying to cut down machining time on our products and most experiments have failed. Parts are being ran on a Mazak Horizontal and taking ~45mins to do a complete set on a tombstone. The holes are a M6x1.0 and we've tried a coolant thru carbide drill but the drill broke on the 2nd hole. I'm wondering if there should be pecking because of the material, but the mfr is telling us not to peck...

 

Any suggestions?

[Mr. M]

Did you have very good coolant flow coming from the drill tip?

[workmantm]

Was the drill coated? What was it coated with? If the coating has any aluminum in it, the chips will want to stick and bond to that. ZrN is the optimal coating. I've gotten away with AlTiN and TiAlN in 6061 and 7075, but I doubt I would even try it in near pure. Try a TiCN or ZrN coated tool.

 

Would Interpolating the hole and reaming it run better? You know you're making a chip that way. Get something like the OSG Blizzard line that throws the chips out and can ramp down at high angles.

[jeff]

What grade of Aluminum?

Would that be considered zero temper? If so, I know for a fact that 0 temper is like trying to cut bubble gum. It's that bad.

As said above, ZrN and TiCN coatings are the go-to for Aluminum coatings.

TiN is a good choice also and probably the most widely available.

[JeremyV]

@ Workmantm: I think it looked like TiCN coated, I can't be sure (I wasn't the operator). Coolant flow was good, i mean it was a thru coolant drill. As for Interpolating the holes + reaming, that is something we don't want to do.

 

@ Jeff: Its 99% pure aluminum GRADE 1350

[jeff]

@ Jeff: Its 99% pure aluminum GRADE 1350

 

Hmm I have no experience with that grade of Aluminum.

 

Do you know the brand and model # of the drill you're using? What speeds and feeds were you running?

[jeff]

Have a look at this Guhring pdf. Starting on page 56 for Aluminum.

 

http://www.guhring.com/Documents/Catalog/Drills/FullLineDrills2013.pdf

[workmantm]

I do a part made from 1100 aluminum, but it's a formed box with thin walls. We use single flute End Mills and put a decent chip load on them. I'm putting Ø.100 holes thru .060 walls. We have to have near full support under the material when we drill it or is just wants to push out of the way. It's a gummy PITA to deburr those surfaces as well. Sanders are the only thing that we have found to work for that.

 

That's the best advice I can give from our experiences. Milling and interpolating your holes seem to be the most efficient means of hole making in these gummy materials. I'd venture the deeper you get the worse it will be. Probably would try a HS peck to ensure you break a chip and use HSS coated drills. They are a little more forgiving if the chip doesn't evacuate very well.

[Prodoggg]

The Guhring drills are nice for alum., the back of the flutes are lapped for chip ejection. Try not running too fast of a feed rate so the chip is not so thick and does not rub against the inside of the hole and gall. I have had to use a G73 peck cycle in gummy materials with carbide tsc drills in the past. It may help with chip evacuation. Good luck.

[The_kid]

Why wouldn't a Dubbed drill designed for copper work? This would be my first consideration.

[The_kid]

also carbide usually doesn't do well with pecking because of the shock. I think a dubbed parabolic HSS drill would do well.

[jeff]

also carbide usually doesn't do well with pecking because of the shock. I think a dubbed parabolic HSS drill would do well.

What do you mean by dubbed?

I've been pecking with solid carbide drills for 20 years. /shrug

[The_kid]

dubbing a drill modifies the rake angle of the drill. you are putting a facet perpendicular to the direction of the cut. so that there is a zero rake angle maybe .005" wide.