I have been struggling to get a reasonable life out on an insert boring bar. The dimensions of the bore continually get smaller as the insert wears. Upon removing the insert the cutting edge is in reasonable condition except for the radius which is badly worn. The bore is fairly short and has two “steps” one with a depth of cut of ~60 thou and the other 10 thou. Between the two the length of cut is .350. The rad is .008 thou and the feed .003 per revolution. The speed is 550sfm. You can see the dept of cut on the insert clearly when looking down on the face of the insert. Can someone explain why the radius is so badly worn while the cutting edges up higher are in fine condition. And how I can remedy this situation. Thanks,
Liam