turning chrome

[seawolf217]

hey guys,

i'm turning some powder chrome parts right now. I'm having some issues, because its burning through my tools. What type of feed and speed should I be running? The part OD is 1.25" and I'm using carbide inserts. I can't use coolant because it might contaminate the material. I'm spraying deionized water on it from a spray bottle as its cutting. I'm getting a crappy finish and its killing my inserts. Any suggestions?

Thanks!

[ZipSnipe]

What type of metal is it? Chrome can be steel, aluminum or even copper.

[seawolf217]

sorry about that, its cobalt chrome

[Mcgyver]

not my area of expertise, but i've only heard of chrome being machined via abrasives, ie ground.

Zip, just wondering, why would it matter what what the base metal is? hard chrome is chromium plating right....and would be just as hard regardless of the base material, no?

[cadman@teluspla]

I had good success with Kennametal CNMG432 in a KMF grade
we were turning IHCP bar.
you can only take shallow cuts but it does a nice job
also good finishing with Kennametal CNGA432T0420 ceramic
also very shallow cuts .005 max on IHCP, with no interuptions

[PixMan]

If you can't use ceramic inserts due to their large tool nose radii (often round inserts), try using Valenite's new VP9605 grade of carbide. A friend of mine is using it in their Ciitzen screw machines with good results. Slow cutting speed (I think he said 110 sfm) but reliable performance.