The Effect of the Variation of Tool End Geometry on Material Removal Mechanisms in Nanomachining

The selection of effective and optimal machining parameters is a major challenge for the manufacturing industries. The tool-work interactions may be affected by many process parameters including depth of cut, cutting speed, feed rate, cutting tool geometry et cetera. Proper selection of these parameters is critical in material removal processes. The effect of different geometric end shapes on the phenomena of rubbing and ploughing in nanomachining was investigated by using the Molecular Dynamics (MD) simulations. The shapes used were flat, pointed, spherical and trapezoidal. The tools in increasing order of sharpness are the following, namely; the tool with the flat end (least sharp), the tool with the spherical end, the tool with the trapezoidal end and the tool with the pointed end (sharpest). The tools show the initiation of ploughing in that order. The tool with the flat end geometry shows a fast initiation of ploughing, because it has the largest surface area to engage more atoms. The total energy is lowest for the tool with the pointed end and highest for the tool with the flat end. All the tools clearly show the phenomena of rubbing and ploughing in the depth of cut range of 0.05 to 0.5 nm. The tool with the pointed end has the lowest average cutting force and the tool with the flat end has the highest average cutting force. It is important to note that in nanomachining the tool with sharpest end may not necessarily cause the greatest material removal! The different tool ends may be suitable for different semiconductor and metal machining applications.