Lean manufacturing is a business model and collection of tactical methods that emphasize eliminating non-value added activities or waste, while delivering quality products on time at lesser costs with greater efficiency.
In the U.S., lean implementation is rapidly expanding throughout diverse manufacturing and service sectors such as electronics, aerospace, furniture production, automotive, and health care as a core business strategy to create a competitive advantage.
While the focus of lean manufacturing is on driving quick, quality, service, continual improvement in cost, and with this significant environmental benefits typically occur incidentally as a result of these production-focused efforts.
Lean principles are derived from the Japanese manufacturing industry. The term was first coined by John Krafcik in his 1988 article, “Triumph of the Lean Production System,” based on his master’s thesis at the MIT Sloan School of Management. Krafcik had been a quality engineer in the Toyota-GM NUMMI joint venture in California before coming to MIT for MBA studies.
For many, lean is the set of “tools” that assist in the identification and steady elimination of waste. As waste is eliminated quality improves while production time and cost are reduced. A non exhaustive list of such tools would include: total productive maintenance value stream mapping, single point scheduling, Five S, pull systems, poka-yoke (error-proofing), , elimination of time batching, mixed model processing, rank order clustering, redesigning working cells, multi-process handling and control charts (for checking waste).
There is a second approach to lean manufacturing, which is promoted by Toyota, called The Toyota Way, in which the focus is upon improving the “flow” or smoothness of work, thereby steadily eliminating mura or “unevenness”. Techniques to improve flow include production leveling, “pull” production (by means of kanban) and the Heijunka box. This is a fundamentally different approach from most improvement methods and requires considerably more work than basic application of the tools, which may partially account for its lack of usage.
The difference between these two approaches is not the goal itself, but rather the prime approach to achieving it. The implementation of smooth flow exposes quality problems that already existed, and thus waste reduction naturally happens as a consequence. The advantage claimed for this approach is that it naturally takes a system-wide perspective, whereas a waste focus sometimes wrongly assumes this perspective.
Both lean and Toyota’s views can be seen as a loosely connected set of potentially competing principles whose goal is cost reduction by the elimination of waste. These principles include: pull processing, perfect first-time quality, waste minimization, continuous improvement, flexibility, building and maintaining a long term relationship with suppliers, automation, load leveling and production flow and visual control.
Toyota’s view is that the main method of lean is not the tools, but the reduction of three types of waste: muda (“non-value-adding work”), muri (“overburden”), and mura (“unevenness”), to expose problems systematically and to use the tools where the ideal cannot be achieved.
Many of these lean manufacturing methods are implemented at the manufacturing firms within the LDFA district of Huron Township, MI.