Mechanical analysis of local cutting forces and transient state when drilling of heat-resistant austenitic stainless steel

In the present research work, mechanical aspect of transient state in drilling operation is investigated by analyzing together the cutting forces and the chip formation. Particularly, a sudden peak occurring on cutting forces during transient state is observed and deeply studied. To do so, new experimental methodologies to analyze local cutting forces when drilling heat-resistant austenitic stainless steel are introduced. The chisel edge and the cutting edge of each studied drill are numerically discretized as series of elementary cutting edges. Therefore, local cutting force evolution is correlated with the local cutting geometry variation along the cutting edge. On one hand, results have shown that for high ductile materials, local cutting geometry affects deeply not only the chip shape but also the chip flow direction. This strongly disrupts the monotony of the cutting forces evolution in transient state and lead to a sudden peak occurrence on cutting forces. On the other hand, linear local cutting forces could be determined by numerical decomposition of the global cutting forces measured during the drill tip engagement.