A simulation-enhanced value stream mapping approach for optimisation of complex production environments

Value stream mapping (VSM) is a widely adopted method for transformation of production environments into a lean operational state. The straightforwardness as well as the completeness, with which processes are analysed and optimised, are key to the success of the method originating from the automotive industry. However, these attributes of the 'paper and pencil' approach result in limitations when applying VSM in complex production environments. This research paper targets to overcome these limitations, specifically in production environments involving significant demand variability, complex routing and cost factors which potentially increase with lean implementation. For this purpose, an enhanced VSM method is developed, which utilises discrete event simulation (DES). The method features a feasibility and trade-off analysis which is incorporated into the VSM procedure. A case study covering a process of exhaust gas purification catalyst production is then conducted to test the newly developed method. The VSM project yields a shop floor lead time reduction from 11.4 to 1.4 d. The additional DES feasibility and trade-off analysis determines customer demand fulfilment and quantifies the monetary benefit of the future state. In that way, potential iterative implementation which is inherently oppositional to the lean philosophy is avoided.