An analytical modelling approach based on Oxley's predictive machining theory is presented to evaluate the cutting forces, chip thickness and temperature distributions in the orthogonal cutting process. In this approach, the work material properties are modelled using the Johnson–Cook constitutive material law, which represents the flow stress of the material as a function of strain, strain rate, and temperature. For the determination of the tool-chip interface temperature, an evenly distributed rectangular heat source near the cutting edge is used instead of a plane heat source. The tool thermal model is simplified by neglecting the temperature variations along the tool-chip interface to avoid the high cost of computation time. Finite difference method is applied for solution of the thermal model. The performance of the developed model is validated with the experimental data in machining of steel 1045. A comparison of the outputs from Oxley's original model and the modified model is provided. The model is further assessed by using two other materials, Al 6086-T6 and Ti6Al4V. Close agreements with experimental results have been shown.