Abstract
To understand the mechanisms of material removal at extremely small depth of cut and brittle-ductile transition in material removal process, molecular dynamics (MD) computer simulations of microcutting of defect-free monocrystalline silicon are carried out. MD simulations show that chip removal under nanometric undeformed chip thickness takes place in ductile mode as a result of "viscous flow" of amorphous region following the phase tramsformation from crystalline to amorphous by plowing of cutting edge. The work surface shows amorphous structure with large tensile residual stress. The simulation also suggests that the tensile stress level intermittently generated as a result of discontinuous chip forming increases as the undeformed chip thickness increases. Therefore, in case of cutting under large undeformed chip thickness, brittle mode material removal and/or sub-surface damage may take place even on a defect-free brittle material.
