Int. J. Much. Tools Manufact. Vol. 29. No. 4, pp.535-553, 1989. 0890-6955/8953.00 + .00 Printed in Great Britain Pergamon Press plc AUTOMATIC TOOL SELECTION FOR ROUGH TURNING OPERATIONS S, J. CHEN*, S. HINDUJA* and G. BARROW* (Received 22 February 1988; in final form 28 November 1988) Ahstract--A method of automatically selecting cutting tools for rough turning operations on a CNC lathe is presented. While the selection procedure can deal with various economic objectives, only the minimum cost per component is considered in this paper. Selection is made from an appropriate tool library and in order to reduce the search time a heuristic method is employed. The cost of machining with a given tool is estimated following the determination of the cutting conditions consistent with the constraints acting on the process. From a detailed examination of the constraints it is possible to ascertain whether the next tool in the library will give improved cutting conditions and the possibility of a lower cost. This procedure eliminates the need for an exhaustive search of the library and results in a very fast and efficient algorithm, The results of ten tool selections are presented. In all cases the computation time for the heuristic approach was less than 5% of that for the exhaustive search. In eight out of ten cases the heuristic method selected the same tool as the exhaustive search; in the two cases where the tools selected were different, those selected by the heuristic method produced only a marginal increase in the operation cost. a arnin~amax atm~x a~ f,,fm D, D~ E Fo F~ F~ F~ Fvmax I Fvmax2 Yvmax3 h k K k, l L L~ N.,N.,N~ N,, N2 e~ R r r~ $ Srnin, $mux T t t2 t3 NOMENCLATURE depth of cut (mm) minimum and maximum depths of cut for chipbreaking (mm) maximum depth of cut limited by the cutting edge length and approach angle (ram) maximum stock to be machined (ram) constants in the tool life equation radial and rotational flexibilities of the workpiece at the point where the cutting force is applied (ram/N) maximum permissible tool deflection (mm) maximum permissible radial deflection of workpiece (mm) Young's modulus of elasticity (N/ram2) axial cutting force (N) radial cutting force (N) tangential cutting force (N) clamping force (N) tangential force limit to prevent circumferential slip of the workpiece (N) tangential force limit to prevent the workpiece being thrown-out (N) tangential force limit due to machine power (N) thickness of insert slope of line mp in a-s diagram (Fig. 2) tool approach angle (°) stiffnesss of tool (N/mm) length of the workpiece in the chuck (mm) length of the workpiece from the chuck (mm) effective insert cutting edge length (mm) speeds at points where the power-speed curve changes (rev/min) critical constraints limiting the values of a and s respectively plan angle power at points where the power-speed curve changes (kW) tool nose radius (mm) workpiece radius at the cutting point (mm) workpiece radius in the chuck (ram) feedrate (mm/rev) minimum and maximum feedrates for chipbreaking (mm) tool life (rain) operation time (min) machining time (rain) tool change time (rain) *Department of Mechanical Engineering, UMIST, Manchester, U.K. M)'~I 2g:4-E 535