High-quality smooth finishing of blade-like geometries via G1 multi-pass 5-axis flank CNC machining using conical cutting tools

Abstract

Existing multi-pass planning methods often result in undesirable gaps or overlaps between adjacent paths of a cutter. These gaps and/or overlaps in the path-planning stage cause artifacts in the physical machining and these locations must be polished as a post-process using either a tiny ball-end cutter and/or by hand-polishing. While highly curved or convex geometries are impossible to be flank CNC-machined with conical tools, certain hyperbolic geometries, like blades of blisks, admit a new path-planning strategies that aim at smooth surface finish by joining neighboring flank paths of the tool with $G^1$ continuity.In this paper, we further develop the approach of flank milling with conical tools such that the surface finish is as smooth as possible in terms of the continuity of the neighboring paths, verify the effectiveness of the method by physical machining of a particular testcase blade geometry, and show that our machining paths reduce the machining error by up to 85$\%$ while maintaining the same machining time when compared to a state-of-the-art commercial software. Moreover, in the vicinity of the boundaries of the paths, the proposed approach basically eliminates the approximation error caused by the transition from one path to another, providing smooth surface finish, and consequently avoiding the necessity of post-process polishing.