Numerical Prediction of Three-Dimensional Unsteady Temperatures in a Rotating Cylindrical Workpiece Subjected to Localized Heating by a Translating Laser Source

Because of their favorable properties at elevated temperatures, high strength, high toughness ceramic materials and superalloys can significantly enhance performance in many engineering systems. The brittle nature of ceramics and high hardness of superalloys require slow and costly finish machining processes, such as grinding or diamond cutting. Laser assisted machining (LAM), in which the material is locally heated prior to material removal, provides an alternative machining process potentially yielding higher material removal rates, improved workpiece properties, an increased ability to precisely control part geometry, and substantial cost savings. In this study, three-dimensional unsteady calculations have been performed for a rotating cylindrical workpiece subjected to localized heating by a translating laser source. Calculations are used to identify operating conditions for which a quasi-steady approximation may be made, and to assess the influence of operating parameters on the three-dimensionality of the temperature field. Results are stated in terms of dimensionless parameters, values of which reveal the relative importance of advection, conduction, convection, and radiation on thermal conditions. Scaling is used to facilitate interpretation of the calculations and to infer relations suitable for approximate analyses.