Modeling of Static Surface Error in End-Milling of Thin-Walled Geometries

Abstract

In recent years, machining replaced metal working and assembly operations as a process to fabricate thin-walled components in the monolithic form. End Milling is preferred machining operation for such components due to its versatility to generate complex shapes in a variety of materials with high quality and productivity. End Milling is an intermittent cutting process with periodically varying cutting forces that causes deflection of thin-walled components owing to lower rigidity. The inherently low stiffness of thin-walled components introduces machining challenges related to static deflections of components. These deflections will result into significant amount of surface error and violation of machining tolerances. Therefore, prediction and control of surface error is an important task for process planners in achieving dimensional accuracy. This paper presents Finite Element Analysis (FEA) based methodology to predict static deflections of thin-walled components during end milling operation. The FEA model inputs cutting force values from two different variants of Mechanistic model existing in the literature and predicts static deflections. The values of deflections estimated from FEA model are transformed further into error profile using surface generation mechanism. An existing classification scheme has been modified to correlate cutting conditions and surface error profile. The results conceptualized based on surface generation mechanism are validated by performing computational experiments using commercial FEA package. The paper also investigates some of the important issues prevailing during machining of thin-walled components such as thinning and end effects.