Micro-structural analysis of chip formation during orthogonal machining ofAl/SiCp composites

Discontinuously Reinforced Aluminum (DRA) Composites form unique case from the research in metal cutting point of view. Reinforcement in these materia l acts as "macroscopic" and "isolated" discontinuities in the path of the t ool. The mechanism of chip formation for such materials is yet to be evolve d completely. In this paper, the mechanism of chip formation during machini ng of Al/SiCp composites based on the micro-structural analysis of chips an d chip roots is presented. It was evident that the mechanism involves initi ation of a gross fracture on the chip free surface and its propagation towa rd the tool nose. The extent of propagation of gross fracture depends upon the cutting speed and volume of reinforcement in composites. A model of def ormation of the material along the shear plane is presented in terms of a r atio of length of flow-type deformation on the shear plane to the total len gth of shear plane. Influence of volume of reinforcement in composites and cutting speed on the ratio was verified experimentally.