Productivity Improvement Strategy in Oil Seal Manufacturing Using Lean and Cost Time Profile Approach

This study aims to improve the productivity of the oil seal manufacturing process at PT XYZ by applying Lean Manufacturing principles through the integrated use of Value Stream Mapping (VSM), line balancing, and the Cost Time Profile (CTP) method. Initial observations showed that the production line experienced significant non-value-added (NVA) activities, particularly waiting time between curing, post-cure, and trimming processes, which resulted in long lead times and high work-in-process (WIP) accumulation. The current state VSM identified curing as the major bottleneck across multiple product families. Improvement strategies were implemented by reducing curing time, adjusting lot size, eliminating deflashing through sensor replacement in trimming machines, reorganizing work sequences, and redistributing operator workloads. The application of line balancing allowed operators to handle multiple machines simultaneously, reducing idle time and improving flow efficiency. As a result, several product families experienced substantial reductions in total lead time, with decreases ranging from 60% to 70%, and increases in value-added ratio. The productivity index also improved, with total output rising from 3,782,400 pcs to 3,808,380 pcs per month, while manpower was reduced from 116 to 100 operators without additional overtime. Analysis using the Cost Time Profile further demonstrated a 3–11% reduction in cumulative cost added per piece. Overall, the integrated Lean Manufacturing and CTP approach successfully enhanced efficiency, reduced waste, lowered production cost, and improved productivity performance in a sustainable manner.