Automatic tool selection for milling operations Part 1: cutting data generation

The selection of tools and cutting data is a central activity in process pl anning and is often liable to an element of subjectivity. It is further com plicated by the wide range of choice presented by the various operation typ es and the huge portfolio of cutters and inserts available from many differ ent tool manufacturers. This paper describes a procedure to select consiste ntly and efficiently tools for rough and finish milling operations performe d on a computer numerical controlled (CNC) machining centre. A wide range o f milling operations is considered, including faces, square shoulders, slot s, T-slots, pockets, holes and profiles. An initial set of feasible tools i s generated that satisfy the constraints of the tool type, the operation ge ometry, the insert geometry and carbide grade, the workpiece material and t he machine tool capacity. Each tool consists of a holder and one or more in dexable carbide inserts. Aggressive cutting data are generated for each fea sible tool using a rapid search procedure in the permissible depth/width/fe ed space for good chip control. The cutting data are further refined by a s et of technological constraints, which include tool life, surface finish, m achine power and available spindle speeds and feeds. The overall cutting da ta optimization criterion is selected by the user from minimum cost, maximu m production rate or predefined tool life. A new optimization criterion, ca lled 'harshness', allows the user to influence the chip thickness that is a chieved for any given cutter. Any feasible tools that fail to satisfy all t he constraints and optimization criteria are discarded.