In this study, we carried out interrupted cutting of carbon steel for machine structure(SM20C) with uncoated carbide tool and analyzed anova test and confidence interval to find influential factor to surface roughness, and obtained regression equation. Rhe results are follows: First, we found that affected factor to surface roughness in interrupted cutting was feed rate. Secondly, the cutting speed and depth of cut was small affected to surface roughness. Finally, from multi-regression analysis of interrupted cutting experimental result, obtained regression equation and it’s coefficient determination was 0.814 and it means that regression equation was predictable. Compared with other continuous cutting, if feed rate increase, surface roughness will grow in interrupted cutting.

As the automobile industry has recently developed, the automobile parts processing industry is also increasing. However, as the processing companies don't have their own studies or facilities now, their productivity is low. And they are in difficult situations because they cannot stay economically competitive. This study measured the cutting force, surface roughness, and tool wear of Ductile Cast Iron(FCD500) used in automobile brake modules in automobile parts to try to help harsh realities of automobile parts processing industry. And it drew the result by taking a test to increase productivity of processing companies as interrupted cutting is more used in industrial settings than continuous processing.

PCBN tools are used worldwide for machining of hardened steel parts in automotive industries. But in heavy interrupted cutting of hardened steel, the tool life is not so stable by sudden breakage of the cutting edge, and total cost of cutting by PCBN is not so economical compared to the grinding. To solve this problem, new PCBN has been developed. New PCBN has very fine and homogeneous microstructure to increase the toughness of sintered body that it provides a reliable tool life for heavy interrupted cutting.