A Framework for Sustainable Lean Manufacturing System Optimization

Thesis Abstract

In the increasing pursuit of operational excellence and environmental stewardship, manufacturing organizations are challenged to optimize production systems that simultaneously maximize efficiency and ensure sustainability. Despite the widespread adoption of lean manufacturing principles, integrating sustainable practices into lean systems remains fragmented, limiting the potential for holistic process improvement. This study aims to develop a comprehensive framework for sustainable lean manufacturing system optimization, addressing the critical need to align efficiency with ecological and social responsibility. The specific objectives are to identify key sustainability indicators relevant to lean manufacturing, analyze the interaction between lean practices and sustainability metrics, and propose an integrated model that facilitates decision-making aimed at system-wide optimization. Utilizing a mixed-methods research design, the study combines qualitative insights from semi-structured interviews with manufacturing managers and practitioners, alongside quantitative data collected through structured questionnaires distributed to a stratified sample of 150 manufacturing firms operating within the electronics and automotive sectors. The purposive sampling technique ensures representation across small, medium, and large enterprises. Data collection instruments include a tailored survey instrument validated through content validity procedures and pilot testing to ensure reliability, achieving a Cronbach's alpha coefficient of 0.87. Qualitative data from interviews are transcribed and analyzed using thematic analysis to uncover emergent themes around sustainability challenges and opportunities within lean systems. Quantitative data are analyzed through multiple regression analysis and structural equation modeling (SEM) to examine the relationships among lean practices, sustainability indicators, and overall system performance. The study anticipates revealing that certain lean tools and techniques—such as just-in-time (JIT), value stream mapping, and continuous improvement—have significant positive correlations with key sustainability outcomes, including resource efficiency, waste reduction, and worker safety. It is expected that SEM will demonstrate the mediating role of organizational culture and leadership commitment in optimizing these relationships. The integration of sustainability metrics into lean frameworks is hypothesized to enhance the overall system performance more significantly than lean practices alone. The research intends to produce a validated integrated model that guides manufacturing firms in systematically implementing sustainability-embedded lean strategies. The primary contribution of this research is the development of a novel, operationalizable framework that aligns lean manufacturing practices with sustainability objectives, facilitating a balanced approach to process optimization. It advances existing knowledge by empirically validating the interplay between operational efficiency and sustainability metrics, grounded in the Theory of Constraints and the Sustainable Development Theory, which underpin the model’s conceptual foundation. The findings are expected to provide practitioners with a clear decision-support tool that enhances competitive advantage while adhering to environmental and social standards. The study concludes that sustainable lean manufacturing can be effectively achieved through deliberate alignment of lean tools with sustainability initiatives, supported by organizational commitment and continuous performance monitoring. Based on the findings, recommendations include the integration of sustainability key performance indicators (KPIs) into lean management dashboards, the adoption of a participative leadership approach to foster a culture of sustainability, and the development of tailored training programs. Future research avenues suggest longitudinal studies to evaluate the long-term impact of the proposed framework across different manufacturing contexts and the exploration of digital transformation’s role in enhancing sustainable lean practices. Overall, this research contributes an empirically validated, theoretically grounded framework poised to guide manufacturing enterprises toward sustainable operational excellence.