C. E. Fischer, Scientific Forming Technologies Corporation, Columbus, OH
Disturbance of part surface integrity by a metal cutting process can substantially decrease the fatigue life of a component, and introduce other difficulties in subsequent metal removal operations. Fatigue behavior is influenced by residual stress distribution near the surface, and by surface microstructure changes, commonly known as “white layer” formation. Finite element simulation of the metal cutting process offers an opportunity to gain a better understanding of the role of cutting parameters on surface integrity. Cutting speed, rake angle, tool edge preparation, tool wear, and coolant all play key roles in residual stress and surface microstructure changes. With simulation, limits can be established which optimize cutting performance and avoid abusive regimes of cutting parameters or tool wear. While there are still opportunities for improved understanding of residual stress, this is an area which has received substantial attention in the literature. Several elastic-plastic finite element codes offer residual stress calculations, so there have been numerous papers published regarding residual stress simulation and measurement. The capability to incorporate microstructure evolution into a finite element simulation of metal cutting is unique. Software featuring microstructure integrated process simulation is demonstrated. Microstructure models interact with deformation, stress, and thermal models to provide prediction of grain size and phase transformations. Case studies demonstrating model capabilities will be presented.
Summary: Finite element simulation is used to better understand the impact of machining parameters and practices on surface residual stress and surface microstructure.