Virtual Simulation and Optimization of Milling Applications—Part II: Optimization and Feedrate Scheduling

The ultimate goal of future manufacturing is to design, test, and manufacture parts in a virtual environment before they are sent to the shop floor. While Part I of this paper presents the modeling of process simulation in a virtual environment, this second part presents computationally efficient algorithms for optimal selection of depth of cut, width of cut, speed, and feed while considering process constraints and variation of the part geometry along the tool path. The objective function is selected as the material removal rate (MRR), and optimization of milling processes is based on user defined constraints, such as maximum tool deflection, torque/power demand, and chatter stability. The MRR is maximized by optimal selection of cutting speed, feed rate, depth, and width of cut. Two alternative optimization strategies are presented. Preprocess optimization provides allowable depth and width of cut during part programming at the computer aided manufacturing stage using chatter constraint, whereas the postprocess optimization tunes only feed rate and spindle speed of an existing part program to maximize productivity without violating torque, power, and tool deflection limits. Optimized feed rates are filtered by considering machine tool axis limitations, and the algorithms are tested in machining a helicopter gear box cover.