Experimental and Numerical Analyses of Ductile Regime Machining of Silicon Nitride

Developments in precision machining technology have shown that ductile regime machining of advanced ceramics such as Silicon Nitride (Si[subscript]3N[subscript]4) is possible under controlled cutting conditions. In the present work, the mechanics of ductile regime machining of silicon nitride at micron level depths was studied experimentally and numerically. Machining tests were carried out for depths of cut ranging from 250 nm to 10 [mu]m on Diamond Turning Machine (DTM). Force and surface roughness data collected from diamond turning of silicon nitride samples were presented. Chip morphology studies were also carried out using Scanning Electron Microscopy (SEM) for the machined samples. The mechanical behavior of silicon nitride is treated using the Drucker-Prager yield criterion and implemented in the commercial machining software AdvantEdge. Numerical simulations were conducted for depths of cut ranging from 1 [mu]m to 40 [mu]m and at rake angles from 0[superscript]o to -60[superscript]o. Pressure distribution at the tool and workpiece interface for different depths of cut and rake angles was studied. Experimental results were correlated with the numerical results for -5[superscript]o and -45[superscript]o rake angles.