Fuzzy value stream mapping in multiple production streams: A case study in a parts manufacturing company

Abstract

Today, many manufacturing companies all around the world are moving forward to be lean, which implies to adapt lean principles to their environment and culture. In their journey, they use tools and techniques to implement lean principles. One of the most promising techniques is value stream mapping, which first portrays the current state as the current state map, then proposes scenarios to improve it as a future state map. Despite having much strength, value stream mapping also possesses two main weaknesses; first, it is effective only in linear production systems, and second, it is not able to consider the variability of the data. In the current research, these two issues are addressed. The proposed method applies fuzzy set theory to mapping the value stream in order to incorporate the variability of data. In addition, the proposed method considers data variability to determine the critical path and map the current state map and to choose the best Future State Map (FSM) between existing FSMs. Finally, for the sake of model validity, the proposed method is implemented on the real case of a parts manufacturing company in Iran.