A Framework to Enhance Green Factories by Applying Lean Production Concepts: A Case Study

In the last decades, competition between several industries to deliver high-quality products is marginally increasing in terms of costs and performance. Lean is one of those activities that focuses on reducing costs by eliminating non-value-added activities. This factory faces various wastes in its production process, including defects, waiting, unnecessary inventory, overprocessing, unnecessary motion, overproduction, and transportation. This study uses a lean manufacturing approach, Value Stream Mapping, to identify and minimize waste, enhance production time efficiency. Meanwhile, green manufacturing is an approach that seeks to achieve measurable and significant environmental improvements. In this research, we study the causal relationship between lean and green manufacturing. We apply several lean tools to enhance the efficiency of a mixed-product production line used in vehicle assembly. A future state VSM incorporating Kanban pull systems, supermarket buffers, and 5S workplace organization was developed and validated. Through the study, we found out that lean and green have a strong relationship in terms of waste elimination, resource efficiency, and environmental impact reduction, where the implementation of lean tools simultaneously achieves both operational excellence and sustainability objectives. Quantitative results demonstrate a lead time reduction from 178.453 to 15.883 days (a 91.099% decrease). These percentages have a direct effect on the flow of materials and information, save raw materials for other uses, free up people to work on other products, and change the amount of electricity used, the amount of water used in cooling systems for injection processes, and the amount of inventory in warehouses. In the end, they affect the percentage of defective products.