machining aluminum bronze alloy 642

[collinsc]

We are having trouble parting off small bushings. The I.D. is .4375 O.D. is .560 after boring the go/nogo gage is perfect.When we part it off we loose the I.D. diminsion. Tolorance on the .4375 is +.0000 -.0005. When i run them on the manuel lathe there is no problem, but on the cnc is where we have trouble. Any help would be appreciated. Material is aluminum bronze alloy 642, AMS 4631-642

 

[btrueblood]

How are you parting them off on the manual lathe, vs. the CNC?

I'll bet you slow down on the feed rate with the manual? Do the same thing for the CNC, this should reduce the amount of deformation the cutter makes on the thin wall as the part seperates.