Lean Six Sigma (LSS) implementation often delivers short-term operational improvements, yet sustaining these gains remains challenging in developing economy manufacturing contexts. This study investigates the critical success factors for LSS sustainability through a dynamic capabilities perspective, examining the differential development of technical infrastructure and socio-behavioural capabilities in South African manufacturing organisations. A quantitative survey of 158 manufacturing professionals in Gauteng Province employed a paired capability assessment instrument measuring current and LSS-improved states. Paired samples t-tests and effect size analysis indicate that technical infrastructure capabilities, including maintenance systems and material handling, demonstrate significant positive gains (average effect size d = 0.55). In contrast, socio-behavioural capabilities, such as communication and knowledge transfer, show limited improvement or decline. This imbalance creates a measurable capability development gap that undermines sustainability. Three organisational archetypes are identified: Technically Advanced (35%), Balanced Developers (28%), and Struggling Implementers (37%). The predominance of imbalanced configurations suggests elevated sustainability risk. The study proposes a five-level LSS Sustainability Capability Maturity Model highlighting the Integration Challenge stage as a critical transition requiring deliberate socio-behavioural investment. The findings provide a diagnostic framework to guide capability sequencing and sustainable performance improvement in resource-constrained manufacturing environments.

Keywords

Lean Six Sigma Sustainability, Dynamic Capabilities, Critical Success Factors, Manufacturing, Capability Maturity, South Africa