From value stream mapping toward a lean/sigma continuous improvement process: an industrial case study

TLDR

Lean manufacturing improves productivity, quality, and delivery, yet the cost of hiring a full‑time lean engineer deters many small businesses. This paper presents a case study of lean implementation at a small U.S. manufacturer. The authors created a current value‑stream map, proposed a future map, identified obstacles, applied the 5‑whys to uncover root causes, and designed kaizen events—including a Taguchi experiment to optimize machining parameters and a rabbit‑chasing approach to enhance flexibility and reduce inventory.

Abstract

Though lean manufacturing has been widely recognised for its effectiveness in continuously improving productivity, product quality, and on-time delivery to customers, the cost for hiring a full-time lean manufacturing engineer has kept many small businesses from implementing lean in their facilities. This paper presents a case study of lean implementation at a small manufacturer in the United States. Starting with collecting process information, a current value-stream map was created that reflected the current operation status. A future value stream map was then proposed to serve as a guide for future lean activities. Next, hurdles that kept the company from moving towards future state were identified. The ‘5 whys’ method was employed to reveal the root cause for each hurdle, followed by kaizen events proposed as solutions. In this case study, two kaizen events were proposed. For the first kaizen event, Taguchi experiment design was used to find the optimal machining parameters that reduced variation in a plasma cutting process. It consequently eliminated rework time and improved productivity. In the second kaizen event, implementation of rabbit chasing increased the system flexibility and consequently reduced inventory levels between work stations.