Alloy 875 - suggestions please!

[SeymourDumore]

Guys, just took on a wicked simple job: 3/8 dia rod, cut to length and drill a 3/16 hole 1.25 deep.
Material is Alloy 875 - and it is ABSOLUTELY KICKING MY ASS!!!

Saw cut was no problem.
Milling the ends was no problem
Drilling OTOH is just not happening!

Tried cobalt with only oil on a Hardinge - Drill melted
Tried Carbide on a CNC with flood - Drills broke
Tried 3fl carbide on a CNC with flood - Drills broke
Tried cobalt on CNC with flood - got 1 part, then drill broke

Speed: 50 SFM ( 1000 RPM ) in all cases
Feed: .0015 - .0025 ( did not want to go lower so it doesn't rub, higher cos the damned thing is hard )
Peck: .15

Have some 400 of these things to do, so hoping someone has some insights as to not use up all available inventory of 3/16 drills, specially now when everything is in short supply.
Have a bunch of coolant through drills coming in on monday for the next try.

Thank You!

 

[plastikdreams]

It's mostly chromium and iron with a bit of aluminium mixed in, probably going to have to drop that peck a bunch, 500 rpm .05 or less peck, 2 ipm, maybe less...I'd start there and see how it goes.

 

[mhajicek]

If all else fails, helix bore with an 1/8" high feed endmill.

Now you know why you got the job!

 

[plastikdreams]

If all else fails, helix bore with an 1/8" high feed endmill.

Now you know why you got the job!

My God that would take forever...but would probably work. Spin it up to like 12k and let er eat!

 

[mhajicek]

My God that would take forever...but would probably work. Spin it up to like 12k and let er eat!

I got 50K

Looks like a 1/8" HFM might be happy around 24K. They don't make them with thru coolant that small though.

 

[SeymourDumore]

So went to 500RPM / .002 IPR / .1 peck, and got 10 parts out of a jobber cobalt drill and it still looks fine.
Substantially slower that I have hoped, but I might just keep some of my sanity.