Cutting insert 6 including {HEAD ~ a groove} formed in the upper surface and extending in {TAIL ~ an axial direction} 
extending in
Cutting insert 6 including { HEAD ~ a groove } formed in the upper surface and extending in { TAIL ~ an axial direction }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL