Lean manufacturing implementation: validation of a readiness assessment model through an empirical approach

Purpose This study aims to empirically validate the Society of Automotive Engineers (SAE) J4000 Lean Maturity Model in the context of industrial companies in the Dão Lafões region of Portugal. Initially developed for the automotive sector, the model had not yet been statistically tested in different industrial environments. This study evaluates its structural validity, internal consistency and suitability as a benchmarking tool for assessing the maturity of Lean implementation. Design/methodology/approach Data were collected from 140 industrial companies using a structured questionnaire with 52 items, covering six dimensions of Lean maturity: Organizational Management and Ethics, People and Human Resources, Information Systems, Customer–Supplier Relationship and Organizational Interface, Product Management and Product and Processes and Process Flow. Reliability analyses (Cronbach’s alpha and composite reliability), exploratory factor analysis and confirmatory factor analysis were performed to assess internal consistency, convergent validity, construct validity, structural stability and model fit (Comparative Fit Index, Tucker–Lewis Index, Root Mean Square Error of Approximation and Average Variance Extracted). Findings The results of this study demonstrate excellent internal consistency (α = 0.9877) and strong construct validity, with all six dimensions aligned with the theoretical framework. The CFA results indicate excellent model fit (Comparative Fit Index = 0.999; Tucker–Lewis Index = 0.999; and Root Mean Square Error of Approximation = 0.001), confirming the robustness, structural stability and adequacy of the six-dimensional SAE J4000 model in a regional small and medium-sized enterprise (SME) context. Practical implications The validated model provides a reliable tool for organizations and policymakers to assess Lean maturity. It also helps identify improvement opportunities and establish regional and sectoral benchmarks. By enabling comparative analysis between companies and regions, the model supports evidence-based decision-making and the development of targeted continuous improvement strategies. Originality/value To the best of the authors’ knowledge, this study presents the first empirical validation of the SAE J4000 Lean Maturity Model outside the automotive industry. This study confirms the reliability and applicability of the model in industrial contexts dominated by SMEs, providing a statistically robust and context-sensitive tool for assessing the maturity of Lean implementation.