Tool and Workpiece Deflection Induced Flatness Errors in Milling of Thin-walled Components

Abstract

The static deflections of cutting tool and thin-walled components during end milling operation contribute significantly towards deviation of a machined surface from the desired level resulting in violation of tolerances. The designer specifies tolerances as per Geometric Dimensioning and Tolerancing (GD&T) standard (ASME Y14.5-2009 or ISO 1101) to transfer designer intent to the manufacturer. The machined surface deviation for straight components translates into flatness error, defined as the normal distance between the two parallel planes encompassing distorted points. This paper investigates the relative contributions of tool and workpiece deflections on the flatness error during end milling of thin-walled components. It is attempted by developing computational models to estimate cutting forces, tool-workpiece deflections and flatness error with associated parameters. A set of end milling experiments are conducted on thin-walled components to substantiate the results. It has been observed that the contribution of tool and workpiece deflections on flatness error has significant dependence on the cutting widths. The outcomes of the present study provides meaningful insights to the manufacturing process planners in determining optimal cutting conditions and strategies to control flatness error during machining of thin-walled components.