Optimization of machining parameters in multi-pass turning and milling operations

The primary objective in machining operations is to produce products with low cost and high quality. Machining parameter optimization plays an important role in achieving this goal. Machining parameter optimization in multi-pass machining operations usually involves the optimal selection of cutting speed, feed rate, depth of cut and the number of passes. In this thesis, the parameter optimization problem for multi-pass machining operations is studied. Mathematical programming models for both multi-pass turning and face-milling operations with single-tool applications are developed based on the minimum production cost criterion. Maximum and minimum cutting speeds, feed rates and depths of cut, as well as tool life, surface roughness, cutting force and cutting power consumption are considered as constraints. Optimal values of machining parameters are found by two methods. One involves using integer programming and the other using nonlinear programming. When solving the optimization problem by the method using integer programming, two steps are adopted. The first step is to minimize the costs for individual finishing and roughing passes for various possible depths of cut. In the second step, an optimal combination of depths of cut for the finishing and roughing passes, the optimal number of passes and corresponding cutting speeds and feed rates, based on minimum total unit cost, are determined using an integer programming model. Examples are presented to illustrate the effectiveness of the optimization models and the solution methods developed. The effect of tool replacement time on the optimization results is evaluated. Certain conclusions related to the problem are made.