Smart Manufacturing-Driven Lean Implementation: Improving Grinding Efficiency and Reducing Costs in Foundry Finishing Operations

Improving operational efficiency is a major challenge in manufacturing environments, particularly in finishing processes characterized by high machine usage intensity and material consumption. This study examines the application of Lean Manufacturing and 5S practices in improving operational efficiency and reducing finishing costs in foundry manufacturing processes. Through Fishbone Diagram analysis, the 5W+1H method, and the application of 5S, this study identifies the main sources of waste related to the use of grinding machine spare parts and grinding wheel materials. Operational data in fie months period showed inefficiencies, including a tonnage-to-cost ratio of IDR 4,086, which was still below the company's target of IDR 4,111, a usage index of 245 kg/IDR, and machine downtime of 6.2%, which exceeded the tolerance limit of 3%. To address this, various improvement initiatives were implemented, including preventive maintenance scheduling, the use of A24 RS type grinding stones, redesigning the ingate, digitizing machine utilization recording, and reorganizing the workplace based on 5S principles. The implementation results from the next five months period showed a significant improvement in operational performance. The tonnage-to-cost ratio increased to IDR 4,641, the utilization index improved to 215 kg/IDR, and downtime decreased to 2.7%. The integration of Lean Manufacturing and 5S practices is effective in reducing waste, improving resource utilization, and enhancing equipment reliability. This study confirms that lean-based continuous improvement initiatives can support the achievement of operational excellence and sustainable cost reduction in manufacturing environments.