Automatic tool selection for milling operations Part 2: Tool sorting and variety reduction

Abstract

The first part of this paper introduced a procedure for rapidly calculating optimized cutting data for all the feasible tools for a given milling operation. Having produced this list of tools with associated optimized cutting conditions, the preferred tool is selected by sorting the list by a composite objective function incorporating a combination of four desirable conditions: maximum metal removal rate, maximum tool life, minimum overall cost and minimum overall cutting time. These four criteria are normalized by a constant multiplier and prioritized by user-defined weighting coefficients. The tool selection procedure is implemented in software with a graphical user interface. The system includes material data for more than 750 ferrous alloys and specifications for 35988 possible holder/insert combinations. Several examples are presented to demonstrate the capability of the system and the subtle interplay of technological constraints that makes optimized tool selection a difficult process to perform manually. This automated procedure offers consistent selection of tools with efficient cutting data that can produce considerable reductions in machining cost when compared with non-optimal solutions. This tool selection procedure is designed to select tools and associated cutting conditions for single milling operations. As many machining centres have a limited number of tool positions available for automated tool changing, it is possible that the optimal set of tools for a given component is not the set of tools that are optimal for each operation considered singly. A post-processing method is presented which rationalizes a set of tools so as to reduce the number of unique tools with the minimal decrease in performance when compared with the set of individually optimized tools.