Single Point Cutting Tools

I expect that's 'back rake angle'. Single point tools are used in the basic machine shop tools, the lathe, the shaper, any chisel type tool. A drill is two single points, a double point. The relation has to do with the job in question. The material being cut, the speed of cut desired, and the steadiness of the equipment all factor in the relation of the angles of the tool. The quality and hardness of the tool affect these angles.

Early single point tools dulled quickly and had to have angles carefully adjusted to the job. Modern tools and cutting techniques have changed, but knowledge of basic single point cutting still factors.

The replacable carbide insert bits allowed negative rake, and higher speeds and feeds.

thanks for the valuable answer sir is there any mathematical relations among shear angle,friction angle and backrack angle of single point cutting tool?