Effects and possible role of atmospheric molecules in ultra-micro-cutting of monocrystalline silicon

The effect of atmospheric gas during cutting of silicon monocrystals has been investigated experimentally. Two problems investigated in this study are the change of the critical depth of cut from ductile-to-brittle mode cutting with the existence of air and the change of the cutting force when the atmospheric molecules are sandwiched between the rake face of a tool and chips. The result obtained for the critical depth of cut shows that the value is smaller in air than in a vacuum. On the other hand, it is found that atmospheric molecules can serve as lubricant so that they reduce cutting force if they are sandwiched between the rake face of a tool and chips. This may be one of the reasons why applying ultrasonic vibration in the direction of cutting can reduce cutting force.