The Lean-Sustainability Index (LSI): Design, AHP Weighting, and Pilot Application of a Composite KPI Framework for Automotive Component Manufacturing

Evaluating how Lean Six Sigma (LSS) programmes contribute to the economic, environmental and social dimensions of sustainability remains difficult for manufacturing suppliers, particularly at the level at which improvement decisions are taken. This study designs the Lean-Sustainability Index (LSI), a composite instrument that aggregates ten key performance indicators (KPIs) drawn from five existing plant information systems across the three triple-bottom-line pillars and evaluates it in a pilot application. Indicators are rescaled by min-max normalisation computed within the comparison set and combined by linear weighted aggregation under an assumption-neutral equal-weight baseline; a weight vector elicited from a five-member expert panel through the Analytic Hierarchy Process (AHP) is reported as a supplementary scenario. The index was applied to four concurrent production programmes within one anonymised automotive component manufacturing plant, yielding composite scores between 21.99 and 74.01. Of the forty programme-indicator values, 20 are measured, 16 are simulation-calibrated against the reference programme under a documented protocol, and 4 are contextual plant-level measurements shared across programmes; the evidential status of every value is disclosed at programme level. A complementary employee survey provided organisational context for a phased digitalisation roadmap. The findings are offered as case-based evidence of the framework’s feasibility and decision-support utility, with analytical transferability to comparable supplier settings rather than statistical generalisability.