Abstract
It is well known that the machinability of brass improves greatly by adding lead to brass, but it seems that the cause is yet to solved completely. So, the deformation in chip formation in the case of cutting of leaded brass is investigated and the cutting mechanism is discussed in relation to the chip friction on tool face and the chip form obtained, in order to make clear the adding effect of lead on the machinability. As the leaded brass is ordinarily belong to 6/4 brass having a complex (α+β) structure, the 7/3 brass containing 0∼3% lead is prepared. The low speed orthogonal cutting test (cutting speed: 100 mm/min, depth of cut: 0.2 mm) is conducted to discuss on the cutting resistance, the friction between the tool face and the chip, the chip formation and others. According to the results, it is confirmed that the cutting resistance, the contact length of the tool face to the chip, the friction coefficient on the tool face and others decrease and the shear angle increases, and then it is found that the lead in brasss preads itself and acts as a lubricant on the contact surface between tool and chip.
