Optimization of roughing operations in CNC machining for rapid manufacturing processes

This paper presents a method for optimizing roughing operations in CNC machining, particularly for parts production through a subtractive rapid manufacturing process. The overall objective is to utilize the characteristics of CNC machining (rapid removal rates, suitability for a wide range of materials and precision) whilst obtaining some of the benefits of additive manufacturing (shape flexibility and reduction in process planning effort). The roughing operation in machining is primarily used to remove the bulk material and to approximately shape the workpiece towards the finished form. The manufacturing process described, utilizes a three-axis CNC machine with an indexable fourth axis device that is used to hold and rotate the workpiece. The method uses multiple approaches in roughing operations that differ in the number of orientations and the angles of the orientations. Most of the machining parameters are generalized throughout the process to allow some automation in generating the machining programme. The performance of each of the approaches is evaluated based on the lowest machining time to produce the part.