Abstract: The cutting experiments of high quality medium carbon steel 45^# and GCr15 bearing sleeve are conducted using two kinds of carbide cutting inserts with different grades and different groove profile.According to the metal cutting principle and analytical method of processing economics, the action mechanism of machinability of parts to production efficiency and production cost is studied with the goal of revealing the regular.Then the inner link of insert service life, machinability coefficient of work-piece and global hardness is explored through cutting experiments.The researches show that the processing costs will be indexed reduce as the improvement of machinability coefficient, insert service life lengthening and drop of work-piece hardness;meanwhile, the production efficiency will get doubled.In the research process, the quantitative relation curve between insert service life and processing economy is obtained to implement the quantifiable objectives of cutting process optimization.The research data and methods can provide methods and data support for the optimization of cutting process and tool design.