A study on manufacturing complexity and difficulty in a mixed model assembly line

Abstract

In the automotive industry, most of the major manufacturers have concentrated their capabilities to develop mixed-model production systems as a key enabler of a flexible manufacturing system. With a trend of increasing product variety, the flexible manufacturing system, which produces various products in small volume with limited resources and reasonable cost, becomes the major competitive advantage of manufacturing companies. However, the mixed-model production system meets some problems by an acceleration of the diversification trend. Diversification of products causes a dramatic increase in manufacturing complexity and imposes additional processes with extra cost on manufacturing systems. Nevertheless, quantitative indexes which estimate manufacturing complexity are relatively insufficient. For this reason, a study about manufacturing complexity is needed and this paper is one such effort to estimate manufacturing complexity. This thesis proposes a reliability based complexity model to estimate the manufacturing complexity of mixed-model production systems in the manufacturing industry and validates it through a simple experiment in a small scale assembly line. After that, an application case study is introduced with real production data from the automotive manufacturing industry. In the case study, the model can compute the reliability of assembly processes from process information of the system. Based on the result, manufacturing engineers can get feedback on such things as the current status of an assembly line or the efficiency of a redesigned system. Furthermore, with accurate and specific process information, the model can forecast unintended costs or errors in the system. For example, the model can anticipate downtime caused by mistakes made by an operator in a mixed-model assembly line. As a characteristic of the automotive industry, there are lots of models, options and parts and, furthermore, automobiles are composed of numerous parts. Because of that, the manufacturing system is very complicated and estimation of the manufacturing complexity is more significant. For this reason, the reliability based complexity model can contribute to the growth of the automotive industry by providing an opportunity to optimize manufacturing systems as a decision support tool.