Designing for operational excellence: integrating lean production and theory of constraints in a greenfield setting

Lean production is a cornerstone of operational excellence. However, while most prior studies address Lean improvements in existing systems, little is known about how Lean principles apply to the design of an entirely new production system. This paper adopts a design science approach to study a Brazilian metalworking company that sought to develop a new manufacturing line based on Lean. Our findings show that, even under seemingly ideal conditions, a new system is not inherently Lean at its inception but evolves toward Lean performance through successive stages of design, ramp-up, and sustainment. To explain this evolution, we introduce a theoretical framework that distinguishes between these stages and highlights the enabling role of adaptability and responsiveness, which are operationalized via Theory of Constraints (TOC) practices such as constraint and buffer management. We demonstrate that framing a new system as a traditional continuous improvement initiative can lead to dysfunctional outcomes when variability and uncertainty are underestimated. Instead, mechanisms such as design-to-adapt and prepare-and-adapt, together with the strategic use of interchangeable buffer types, are essential to support system evolution. This study therefore clarifies how one can combine Lean and TOC to design a new production system and build its operational excellence from the ground up.