Scheduling in dial-indexed production lines

An innovative approach to maximize throughput in dial indexes flow lines provided by an automatic and synchronous part transfer mechanism is outlined. In this class of production systems, the performance measures are directly related to the control operating method, defined as the schedule of activities performed by the part transport mechanism and the workstations during each dial cycle. Usually, a unique operating method (i.e. the main operating method) is adopted to control the production flow and is designed to process any part type workable in the system, independently by the required part program. In order to design higher-performance systems, current industrial research is focused on the implementation of more efficient hardware technologies. However, technological and economical aspects sometimes limit greatly the possibility to have remarkable results. The goal of the proposed solution was to improve system performance by optimizing the control and management methods and without any expensive change in the system hardware. The approach was based on the definition of new operating methods characterized by a throughput value higher than the one of the main operating method. In a second step, an integer linear mathematical programming model was formulated to sequence the parts at the loading station in order to maximize the system throughput. An actual application was analysed to assess the validity of the proposed approach. Computational experiments have shown a remarkable increase in system performance.