Enhancing operation efficiency of leather manufacturing industry through hybrid of value stream mapping and discrete event simulation

Abstract

Traditional value stream mapping (VSM) has played substantial role in reducing lean wastes in the manufacturing sector overall as well as specifically within automotive companies. However, it provides only a static view of linear production systems with limited process details. This research is conducted in the case of leather industry. The case study is challenged with work -in- progress inventory, unnecessary processes, long waiting time, and long lead time. Therefore, the purpose of this research is to address literature gaps and challenges faced by a case leather company and enhance operational efficiency by combining VSM with discrete event simulation. Product matrix analysis is used to categorize leather goods into product families and select a representative product. Data collection involves direct observation (Gemba-walk) and report reviews. Numerical results from the enhanced current state VSM (ECSVSM) quantify value-added time, non-value-added time, value-added ratio, Takt Time, and total production lead time as 2198.24 s, 14.59 d, 0.54%, 230.1 s, and 14.67 d, respectively. This ECSVSM data is then applied to develop a simulation model of the As-Is system. Based on findings from the ECSVSM and As-Is simulation, shop floor wastes are identified. Alternative scenarios are proposed to mitigate these wastes, with one scenario selected along with additional proposals involving 5S, supermarkets, and layout adjustments. A future state VSM incorporates these solutions. Results demonstrate major improvements, including enhanced operational efficiency up 8.16%, and reductions in non-value-added time by 42.9%, lead time by 42.72%, alongside increased value-added ratio by 55.56% and lowered key waste categories.