Machining Chromium

[JeremyV]

i'm working with "CHROME, Cr, 99.95% PURE" Chromium - no alloy mixture of any kind.

 

We need to put a 30deg chamfer on one side and there could be some milling, but overall we need to put a .22 thru hole with a .34 x .25dp c-bore. Material is .375 thick. Going to be drilling 36 holes...

 

So...recommendations?

 

Boss is thinking 2 carbide drills would be enough but I don't quite think so.

 

I do know that the only thing we've done on this material in the past is facing them to thickness very slowly with a 6" facemill, but the rest with drilling and milling is new to us. I've considered running this @ Chromium Carbide cutting feeds/speeds using only carbide tools.

 

Any advice would be appreciated!

 

-JD

[Guest]

Is EDM an option?

 

[JeremyV]

lol....thanks for the laughs =P but wow....84 views and only one said EDM =P

 

No sadly... =(

 

I did some testing with carbide tools... I find it funny the hss spot drill actually lasted all the holes i test drilled.

 

Anyway managed to get 20 good holes out of a carbide drill at 30SFM and 1.5IPM, but it managed to drill 53 holes with a chipped tooth.... go figure. I wonder if its because of the drill hitting the aluminum jaws that we used to hold the part with. The drill breaks at 50 SFM.

 

Milling @ 60-80SFM. Facing with inserted facemills @ 200SFM. pretty much gotta go slow with this. I've had a few people at work asking me whether to try an OSG drill on these.... i dunno if i'm willing to risk that because of the 30 SFM on the carbide drill.

 

/shrug....

[Guest]

That is awful slow for carbide (probably why it chipped). But you're pretty much hamstrung because of that material.

 

Usually the exotic stull will at least elicit some humor. Not this time eh? Could be worse. Could be Stellite.