Deep Drilling Aluminum Bronze

[nissan300ztt]

So in my companies infinite wisdom they have decided to quote a job that needs to be done tomorrow. I have to drill 21-5/8" Deep using an 11/16" HSS drill. However im noticing that this material seems to be very hard. Never had to cut it before. So Im wondering whats the best advice you all could give me to get this done. Ordering tooling is not an option here. My company is far too cheap to buy nice things. It will going into a CNC and G83 Peck Drilled im just unsure of RPM and Feed and Depth per peck. Thank you.

 

[nissan300ztt]

Oh and I forgot to add it is a blind hole.

 

[mhajicek]

HSMAdvisor is recommending 361RPM, 3.09IPM, and 1.9" pecks. I strongly recommend a spot drill, then a pilot with a shorter drill of the same diameter (ideally a screw length and then a jobber length) before going in with your extra long drill.

 

[Milland]

Drilling Aluminum Bronze - Google Search

A few threads on PM on this, should help you. You might want to bore a pilot hole to give yourself the best chance of staying on center if that matters.

 

[implmex]

Oh man, they really handed you a flaming football, didn't they!
What grade of aluminum bronze?

These materials do not drill well in my experience.
The secret is to keep the drill very very sharp and never ever EVER let the job get hot.

Depending on the grade, it'll do all kinds of weird shit, some grades work harden in a heartbeat, some eat drills for lunch, some contract around the drilled hole and grab the drill twisting it off instantly.
Some warp like noodles if you overstress them, especially with heat, but also when you remove material from them.

If HSS is going to be your drill material, I hope you have a drill grinder and a bunch of drills you can rotate between.

I have never found a grade that is "easy"
I have found 954 to be the easiest grade for me to work with, but I have the most experience with that grade.
623 and 624 are also not too bad.

The nickel bearing aluminum bronzes are pretty bitchy to drill in my experience.
So are the Toughmet alloys.

I've done better with carbide drills than with HSS.
Those who drill it routinely seem mostly to use carbide through coolant drills with high pressure coolant, and push them pretty briskly to keep from work hardening the bronze.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[Booze Daily]

I’ve done lots of 630 grade. Seems to like 70-90 sfm

Shallow peck, keep it cool.

Like Marcus says it will shrink on your drill.
You’ll probably have to resharpen before you finish the hole. Good luck.

 

[dandrummerman21]

HSMAdvisor is recommending 361RPM, 3.09IPM, and 1.9" pecks. I strongly recommend a spot drill, then a pilot with a shorter drill of the same diameter (ideally a screw length and then a jobber length) before going in with your extra long drill.

Seat of the pants at home, I would be thinking ~250rpm at 2.5-3ipm, but nowhere near 1.9" pecks in aluminum bronze.

Maybe 1/4" or so if it is behaving.

Start with a short drill. Maybe you have an intermediate drill in the shop too? go as deep as you can before switching to the long one.

try to come nearly out of the hole. Maybe don't exit the hole so it doesn't whip around the mouth. But you also don't want chips to fall back in.

Try to set the return distance for g83 a fair bit off the floor, at least .040" so you don't crash it back onto chips. The chips will likely be small but you don't want to crunch them 20" deep. Probably run rapids at 50% or less also?

 

[cyanidekid]

as usual, the machinists best friend can be a 10 power loupe. stop and check the edge under magnification regularly, and resharpen if needed. AlBr can dull cutters, as the Aluminum oxides (especially if it gets hot, as others have warned) are murder on the cutting edge. if you don't catch it early, it's a death spiral.
(hope you have a loupe or 'scope and ability to sharpen...)

 

[nissan300ztt]

Well this hole manually would take about 5 hours or so is what they quoted. But the only drill long enough in the shop is probably 35 years old and a taper shank at that. So I think im going into my shop tomorrow and telling them im not doing it without a proper cutter. Im reading everywhere that length of drill that deep you wont be able to keep the drill cool enough and wont be able to maintain sharpness for the entire cycle. And yeah im getting really tired of having to "figure it out" non sense. Well wish me luck, Im either going to be breaking off a drill in an expensive piece of material or it will go smoothly, im gonna go with the former.

 

[nissan300ztt]

Oh man, they really handed you a flaming football, didn't they!
What grade of aluminum bronze?

These materials do not drill well in my experience.
The secret is to keep the drill very very sharp and never ever EVER let the job get hot.

Depending on the grade, it'll do all kinds of weird shit, some grades work harden in a heartbeat, some eat drills for lunch, some contract around the drilled hole and grab the drill twisting it off instantly.
Some warp like noodles if you overstress them, especially with heat, but also when you remove material from them.

If HSS is going to be your drill material, I hope you have a drill grinder and a bunch of drills you can rotate between.

I have never found a grade that is "easy"
I have found 954 to be the easiest grade for me to work with, but I have the most experience with that grade.
623 and 624 are also not too bad.

The nickel bearing aluminum bronzes are pretty bitchy to drill in my experience.
So are the Toughmet alloys.

I've done better with carbide drills than with HSS.
Those who drill it routinely seem mostly to use carbide through coolant drills with high pressure coolant, and push them pretty briskly to keep from work hardening the bronze.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Im believe its Amco 18 or "similar"

 

[nissan300ztt]

as usual, the machinists best friend can be a 10 power loupe. stop and check the edge under magnification regularly, and resharpen if needed. AlBr can dull cutters, as the Aluminum oxides (especially if it gets hot, as others have warned) are murder on the cutting edge. if you don't catch it early, it's a death spiral.
(hope you have a loupe or 'scope and ability to sharpen...)

We have a Black Diamond Drill sharper, but at 24" long I dont think its going to hold in the collets very easily.

 

[MCritchley]

Seems like a good hole to drill on an old HBM if you have one.

 

[nissan300ztt]

Seems like a good hole to drill on an old HBM if you have one.

We do, but its not accurate enough in our shop. Its an old King. And doesnt run true at all. Ill give it a shot tomorrow and see what happens.

 

[cyanidekid]

We have a Black Diamond Drill sharper, but at 24" long I dont think its going to hold in the collets very easily.

well, don't know if you can hand sharpen, but even if it cuts on one edge, you are WAY better off than pushing in a dull tool.
start it with shorter drills as others have said, and pilot if you can. with care, regularly inspecting under magnification, and sharpening as needed, seems to me an hour and a half- two tops would get that done on a manual machine.
good luck!

 

[Dan from Oakland]

Watch out for worn margins near the tip of the drill. If they get worn and start rubbing, The heat generated will cause the drill to seize in the hole, and at that point you are hosed. Drilling with a dull drill will create alot of powder that will wear the margins in short order. Any gun drilling shops near you?

 

[eKretz]

Cutting on one edge is actually way WAY better, because the hole won't seize the drill that way. I've done that on purpose at times with aluminum bronze. Best all around is to try to use a carbide tipped drill. Carbide just plain works better on aluminum bronze. If that's not possible - as already mentioned, keep after that edge like a hawk. When it starts to dull, resharpen it immediately. It may need sharpened a few times for a hole that deep.

Also, Dan mentioned margins - that is vital. Don't start the hole with a drill that already has margin wear or you're going to be in for a world of shit. Cut back past any margin wear, THEN resharpen the drill.

 

[Greg White]

Are these coolant holes,heater holes?
I would want to farm it to a gun drill shop..
good luck,your gonna need it.
Gw

 

[guythatbrews]

Maybe management might not like it, but I'd check with a gundrilling shop. They stay away from some materials and this might be one of them I don't know.

If you've gotta do it I wouldnt use a taper shank drill in a cnc. I've seen them pull out of the socket and that's a pretty good crash. If you must use TS figure out some kind of positive retention, pin through the tang or something. A sharp drill and shallow pecks win the day. With one part I'd run it slow, maybe 50 sfm, .007 IPR.

Unless you have an oil hole drill, once you get very deep you are effectively drilling dry. I'd use a macro and make my own cycle or even hard code it. Don't come all the way out of the hole. Dwell there and blast coolant as far down the hole as you can. Arrange the nozzle so it's not blocked but goes down by the flute.

That long a drill in a turret block will be prone to misalignment. Check that carefully.

If sharpening mid-cycle is required, and that is likely, how will you get back to your current depth? Hopefully your lathe has a feature that allows stoping mid-cycle and returning to the cycle.

One-off stuff like this has a big pucker factor. Good luck!

 

[CPM2014]

My experience is mostly with 630 but they all suck. Cobalt drills will be your friend.

 

[garychipmaker]

My experience with drilling a pilot hole in AB is don't go very big as it will grab and pull the drill in if manually drilling.