Cutting force modeling considering tool wear effect during turning of hardened AISI 4340 alloy steel using multi-layer TiCN/Al2O3/TiN-coated carbide tools

This study attempts to develop a cutting force model under oblique cutting conditions considering tool wear effect during turning of hardened steel with coated carbide tools to address metal cutting issues such as tool life, dimensional accuracy, and surface finish. Forces in worn out tool have been modeled by summing up forces in sharp tool and the forces due to flank wear alone. Waldorf's orthogonal force modeling approach is extended to 3-D cutting force analysis to model cutting forces due to flank wear alone. Forces in sharp tool and average interface temperature generated during machining are modeled using regression analysis. Shear flow stress, shear angle, and other model prerequisites are determined using equivalent cutting edge geometry in place of the actual cutting edge of tools having nose radius. Worn tool cutting force model is validated in turning of hardened AISI 4340 steel at different levels of hardness 35 and 45 HRC, respectively, using multi-layer TiCN/Al2O3/TiN-coated carbide tools. The quantitative agreement between experimental result and that of a developed model of worn tool cutting forces is favorably good with an average error of less than +/- 5 % with a maximum error of 11 %, which showed that the developed model is reliable and could be used effectively for predicting the forces in worn out tool within the domain of the cutting parameters.