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Alloy 875 - suggestions please!

SeymourDumore

Diamond
Joined
Aug 2, 2005
Location
CT
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

Diamond
Joined
May 31, 2011
Location
upstate nj
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.
 

SeymourDumore

Diamond
Joined
Aug 2, 2005
Location
CT
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.
 








 
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