Design Principles for Machining System Configurations

Until recently, mass producers have relied on long serial lines of dedicated machines in order to machine products at high volumes. Today, as the cost of CNC machining centers decreases, more and more high-volume manufacturers are examining the alternative of shorter lines with more machines configured in parallel. This paper presents the main principles for selecting the right machining system configurations. We propose a system classification and show that only symmetric configurations are of interest to industry. We compare four classes of systems: pure serial lines, pure parallel lines, short serial lines arranged in parallel, and short serial lines arranged in parallel with the ability to move products between the lines (i.e., with crossover). Specifically, we compare the different configurations in terms of throughput, line balancing, machine investment cost, and capacity scalability. Finally, we introduce an upgradable multi-spindle reconfigurable machine as a cost-effective alternative for system scalability.