The main objective of tool path planning for sculptured part finishing is to attain the required surface-quality and maximum machining efficiency concurrently. This work addresses these challenging and conflicting tasks that demand more research.

The study identifies and mathematically proves a new tool path planning principle for 3-axis sculptured part machining—a steepest-directed tool path is the most efficient tool path scheme for a single tool path. An innovative tool path generation method, integrated steepest-directed and iso-cusped (SDIC) approach, is proposed for 3-axis sculptured part finishing. In this approach, the steepest-directed tool paths form a frame that controls the tool path directions for higher machining efficiency, and the iso-cusped tool paths fill this frame to prevent redundant tool motions and to ensure adequate surface quality. A hemicylindrical part is used to illustrate this approach and to demonstrate its superiority.

To machine complex sculptured surfaces that usually require expensive 5-axis machining, a cost-effective 3½½-axis machining scheme is discussed. The 3½½-axis machining is carried out by rotating the part to the cutter/part orientations that are defined by subdivided surface patches, discretely and sequentially using a tilt-rotary table attached to the 3-axis CNC machine. Under each orientation, the corresponding surface patch is machined using effective 3-axis CNC tool paths, i.e. the SDIC scheme. A method that automatically generates effective tool paths to facilitate the 3½½-axis machining is introduced. This approach optimizes the subdivision of a complex sculptured surface based on surface geometry and identifies the favourable cutter/part orientation for each subdivided surface patch, using fuzzy pattern recognition and Voronoi diagram. The advantages of this approach are demonstrated through a benchmark example.

This work contributes to the automated and optimal CNC tool path generation for sculptured part machining and has potential to benefit the aeronautic, automotive and die/mould manufacturing industries.