Prediction of contour accuracy in the end milling of pockets

Many die and mold parts surface contours are produced by end milling operations. The contour accuracy of the milled pockets is strongly influenced by the cutting tool deflection caused by the cutting forces. For milling a complex shape or a simple rectangular pocket, the accuracy of contours in corner cutting is mainly influenced by the deflection of the end mill caused by the variation of cutting forces. This is believed to be due to variable radial depth of cut in corner cutting between the straight part and the corners resulting in variable contour accuracy. The way to improve contour accuracy in corner cutting is by decreasing the radial depth of cut to reduce the cutting forces and, consequently, the end mill deflection errors. During the cutting process the end mill cutter is subjected to radial and tangential deflections at different segments of the tool path. In order to compensate the tool path for improving the contour accuracy, it is necessary to predict the instantaneous radial depth of cut. A simple tool deflection model for predicting the deflection errors in straight segments and corners for rough milling with slot cutting as well as for finish milling with immersion cutting is presented with illustration of case studies. (C) 2001 Elsevier Science B.V. All rights reserved.