Controlling the Spindle Speed when Milling Free-Form Surfaces using Ball-End Milling Cutter

Abstract

Ball-end tools are widely used in industries such as die/mould, automobile, and the aerospace industry. These cutters are specially used when finishing complex three- dimensional sculptured surfaces. However, when using this cutter, the working diameter is different from the nominal diameter and varies from point to point due to the change in surface inclination. Therefore, cutting speed, which is calculated depending on the nominal diameter, is not accurate. The actual cutting speed changes resulting in several defects in the manufactured surface. This article introduces a new algorithm to improve the NC code of a CNC machine. The presented algorithm combines the STL format file with the APT language file to calculate the required spindle speed in order to provide a constant cutting speed during the entire machining process.