Improving the production cycle in the precast concrete industry using Value Stream Mapping: A case study

Lean Manufacturing has been widely adopted as a systematic approach to improve production efficiency by eliminating non-value-added activities. However, empirical findings on its effectiveness remain inconsistent, particularly in complex production systems that rely heavily on equipment and interdependent processes. This study aims to identify sources of waste and evaluate the effectiveness of Lean Manufacturing implementation using Value Stream Mapping (VSM) to improve production system efficiency. A case-based quantitative approach was employed by mapping the current state of the production process, identifying dominant wastes, and analyzing their root causes using the 5 Whys method. Based on this analysis, improvement proposals were developed and visualized through a future state VSM to evaluate projected performance improvements. The results show that in the current state, significant wastes occurred in the reinforcement preparation, casting, and demolding processes, resulting in a Value-Added Ratio (VAR) of 75.10%. Through the proposed improvement strategies, the future state VSM demonstrates a reduction in cycle time and an increase in value-added activities, with the VAR improving to 86.35%. All major workstations were able to achieve the minimum production target, indicating improved flow stability and work effectiveness. This study contributes to the Industrial Engineering literature by providing empirical evidence on the effectiveness of integrating Lean Manufacturing and VSM in a complex production environment. Practically, the findings offer a structured framework for identifying waste and designing sustainable improvement strategies to enhance production efficiency. The results also support the broader applicability of VSM as a decision-support tool for continuous improvement initiatives.