<b>Enhancing Manufacturing Excellence Through Lean Six Sigma: A Case Study Approach</b><b></b>

Abstract

Achieving manufacturing excellence requires continuous improvement in operational efficiency, quality, and process performance. Although Lean Six Sigma (LSS) is widely recognized for process optimization, its application in complex manufacturing environments remains constrained by the lack of structured, scalable, and empirically validated frameworks, while existing literature remains fragmented and provides limited guidance for sustainable industrial deployment. This study adopts a case study approach to develop and validate a structured Lean Six Sigma framework for enhancing manufacturing performance. A systematic review of LSS applications in manufacturing (2010–2026), combined with a gap analysis, identified key challenges, including inconsistent implementation practices, limited industrial validation, workforce capability gaps, and high deployment complexity. To address these gaps, a comprehensive framework is proposed that integrates the DMAIC methodology with five functional domains: strategic alignment, process analysis, quality improvement, reliability and maintenance, and continuous improvement, with explicit linkages among DMAIC phases, analytical tools, and performance indicators to support structured and sustainable improvement. The framework was implemented and validated in a car spare parts manufacturing company in Egypt, resulting in significant improvements, including an increase in first-time product quality from 26.7% to 80.0%, achievement of 100% post-rework quality, sigma level improvement up to 6.0, and a reduction in processing lead time by more than 50%, alongside an increase in value-added efficiency from 47% to 79%. The findings demonstrate that the proposed Lean Six Sigma framework bridges the gap between theory and practice and provides a scalable pathway toward sustainable manufacturing excellence.