Productivity of parallel-serial manufacturing lines with and without crossover

摘要

The productivity of a manufacturing system is greatly influenced by the configuration of the manufacturing system. However, the number of system configurations possible for a set of manufacturing operations can be very large, causing difficulty in the efficiency of general methods to calculate the productivity. Therefore the focus of this paper will be limited to configurations that are characteristic of automotive machining transfer lines. The traditional automotive line is serial and parallel operations are generally not used except where a balanced line cannot be achieved. Yet productivity gains can be made from parallel lines. Traditional lines also use buffers between operations to isolate the impact of a machine failure on the productivity of the system. However, a buffer does not isolate the failure to complete a product from failure in the last operation. When production machinery is of high reliability, and reduced work-in-process inventory costs are important, the examination of machining lines that do not rely on buffers becomes important. This paper examines the productivity improvements that can be obtained by bufferless parallel-serial lines, i.e. multiple machining lines in parallel, both with and without crossover between the operations. It will be shown that significant improvements to productivity can be obtained by placing operations in parallel, and that there is a synergistic improvement to productivity from having crossover between the operations.