Failure mechanics analysis of AISI 4340 steel using finite element modeling of the milling process

A slot cutting operation is studied in this paper using a rotating/translating flat end milling insert. Milling operation usually comprises up-milling and down-milling processes. These two types of processes have different behaviors with opposite trends of the forces thus making the operation complex in nature. A detailed Finite Element (FE) model is proposed in this paper for the failure analysis of milling operation by incorporating damage initiation criterion followed by damage evolution mechanism. The FE model was validated with experimental results and good correlations were found between the two. The failure criteria field variable (JCCRT) was traced on the workpiece to observe the amount and rate of cutting during the machining process. It was found that the model was able to predict different failure energies that are dissipated during the machining operation which are finally shown to be balanced. It was also shown that the variation of these energies with the tool rotation angle was following the actual physical phenomenon that occurred during the cutting operation. Among all the energies, plastic dissipation energy was found to be the major contributor to the total energy of the system. A progressive failure analysis was further carried out to observe the nature of failure and the variation of stress components and temperature occurring during the machining process. The model proposed in this study will be useful for designers and engineers to plan their troubleshooting in various applications involving on-spot machining.