Effect of component configuration on geometric tolerances during end milling of thin-walled parts

The static deflections of the cutting tool and thin-walled components are key sources contributing to the deviation of a machined surface from the design specifications during the end milling operation. The machined surface deviation is expressed using geometric tolerances such as flatness and cylindricity parameters specified as per the Geometric Dimensioning and Tolerancing ( GD&T ) standard (ASME Y14.5-2009 or ISO 1101). The present work investigates the effect of component configuration, engagement area, and workpiece curvature by comparing geometric errors during the end milling of zero and constant curvature thin-walled components. An integrated computational framework incorporating the mechanistic force model, finite element (FE)-based workpiece deflection model, cantilever beam formulation-based tool deflection model, and particle swarm optimization (PSO)-based geometric tolerance estimation model has been adopted from the previous work of authors. The effect of component geometry and cutter-workpiece transition are investigated on the geometric tolerance (flatness and cylindricity) by conducting computational studies and machining experiments under identical cutting conditions. The concept of “Equivalent Radial Depth of Cut (RDOC)” is introduced to derive component configurations with the identical cutter-workpiece transition area. The influence of workpiece curvature on the geometric tolerance parameters is also investigated in the paper. The outcomes are substantiated by performing computational studies and machining experiments. It is recognized that the relatively enhanced stiffness of the curved components offers an inherent machining advantage in comparison to straight components to the process planners.