A model for the prediction of surface flatness in face milling

This paper presents a new model for the prediction of surface flatness errors in face milling. The model includes the effects of machining conditions, elastic deformation of the cutter-spindle and workpiece-fixture assemblies, static spindle axis tilt and axially inclined tool path. A new method called equivalent flexibility influence coefficient method is used to compute the elastic deflection of the cutter-spindle and workpiece-fixture assembly at the points of cutting force application. Single insert and multi-insert face milling experiments are conducted to evaluate the predictive ability of the surface flatness model. A comparison of the model predictions and measurements shows good agreement. The influence of static spindle axis tilt on the surface flatness error is found to be very significant. It is shown that care needs to be exercised in comparing the model predictions based on elastic deflection of the machining system and spindle axis tilt with the surface flatness error measurements due to the fact that these measurements may be inflated by inclusion of the surface roughness.