Turning 4140 heat treated to R60
I am currently trying to machine some bearing races that have been case hardened to R60 .06 deep. I haven't found anything tooling wise that will machine the part after heat treat that will last longer than one part. I machine the part .02 over size with extra material on the back to help keep warp down. I then turn the .02 off to final size ( to remove warp). Then part off the final race. My inserts are usually shot after one part. I have used several different grades of inserts and even tried a pcd insert. I know that grinding is the best way to do this but the shapes of the race prevent this. Any suggestions?
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