Identification and Quantification of the Seven Wastes (Muda) in Aircraft Structural Assembly: A Systemic Lean-Based Approach

Abstract

Aircraft structural assembly constitutes one of the most complex manufacturing environments, distinguished by low production volume, high product mix, structural criticality, and stringent regulatory requirements. Within this setting, the seven wastes (Muda) defined in Lean Manufacturing assume context-specific forms of manifestation, frequently intensified by operational variability and capacity saturation. This study examines the identification and quantification of the seven wastes in aerospace structural assembly processes through a hybrid approach that integrates Lean theoretical foundations, Theory of Constraints, and quantitative performance analysis. A case study performed on a structural assembly line evaluated cycle time, work-in-process (WIP), rework rate, and non-value-added time associated with waiting and motion. The results show that operational variability functions as a systemic multiplier of waste, exerting direct influence on lead time and the stability of production flow. The structured application of Lean practices, combined with quantitative assessment, enabled measurable reductions in critical waste categories and yielded significant improvements in systemic performance. These findings contribute to the existing literature by proposing an integrated method for the identification and quantification of Muda in complex aerospace manufacturing environments.