Time variability analysis in multi‐production value stream

Value stream mapping (VSM) as one of the practical and strong techniques in implementing the lean production principles has two main shortcomings; first, it is effective only in the linear production system and second, it is not able to give a real insight into the variability of the data pertaining to the production processes. In this paper, VSM in multiple production streams as well as existing variability in data are considered and analysed. The proposed method incorporates the variability in timed data through using an improved programme evaluation and review technique (PERT) and statistical analysis methods in order to determine the critical value stream for mapping the current state as well as select the best proposed future state map (FSM). To illustrate the efficiency and applicability of the proposed method, it is also applied into a real case in a communication parts manufacturing company in Iran.