The form of cutting edge of tools plays on important role in the mechanical working, as it is remarkably affected by the material of tool itself, kinds of steel to be cut and the heat treatment of materials. In the previous paper the authors reported the cutting force and the cutting efficiency of tool tested by an apparatus of Schiess-Defries under various cutting conditions. In this experiment, 3 kinds of steel, (1) annealed, Cr steel, (2) Ni-Cr steel tempered after quenched in oil and (3) austenitic stainless steel, were cut by 2 kinds of high speed steel, (1) 18-4-1 type and (2) Co 5_??_6% and the following problems are investigated: (1) the relation between the form of the cutting edge of tool and the cutting force, (2) the effect of the form of cutting edge on the cutting efficiency, (3) the relation between the form of cutting edge and kinds of steel tested to be cut.
The results of this experiment are as follows:-(1) main cutting force for each steel tested to be cut, is the lowest in the neighbourhood of 60° of cutting angle and the highest cutting efficiency results in 60° of cutting angle for Cr steel, 70° for Ni-Cr steel, and 50° for stainless steel, (2) front clearance angle hardly gives any effect upon each component of cutting force, and the highest cutting efficiency is found in the vicinity of 5° for each steel to be cut, (3) as the side rake angle increases, the cutting force decreases slowly and the cutting efficiency is the highest at 5° for Cr steel, 0° for Ni-Cr steel, and 15° for stainless steel, (4) as the side angle increases, the main cutting force decreases and the cutting efficiency increases as the side angle decreases.