Lean
Lean is the practical application of systems thinking to the improvement of production or productive processes. It combines this thinking with a set of principles, tools and techniques focused on reducing complexity in the production stream. Activities that don’t add value are eliminated. Bottlenecks and other constraints on process flow are likewise taken out of the process to produce a smooth process flow. The result is reduced cycles times, increased inventory turns, simplified and streamlined processes that work faster.
Lean was first defined by James Wolmack and Daniel Jones in their landmark study describing the Toyota Production System (TPS) — themodel for Lean. Since then, Lean has been extended to Lean Enterprise that applies Lean to all areas of organizational functioning from accounting to manufacturing to shipping and from the factory floor to the head office boardroom.
Lean has evolved to become a comprehensive maangement system and philosphy. It is perhaps most easily understood as a rigorous effort at eliminating all forms of waste in the enterprise.
Taiichi Ohno’s Seven Wastes (Muda)
The starting concept of the Toyota productions system was, as I have emphasized several times, a thorough elimination of waste. ( Taiichi Ohno, Toyota Production System: Beyond Large Scale Production in Preface to the English Edition p.xiv) The Toyota production system is a method to thoroughly eliminate waste and enhance productivity. In production, ‘waste’ refers to all elements of production that only increase cost without adding value – for example, excess people, inventory and equipment. (Taiichi Ohno, Toyota Production System: Beyond Large Scale Production p.54)Waste, for Mr. Ohno, is anything that doesn’t add value. He prepared a now famous list of seven wastes that workers (and managers) are expected to watch out for. Ohno’s list is instructive as to the kind of thinking that went into Lean.
The Waste of Overproduction.
Overproduction is producing more of something than is required. Producing more than is required means producing too much, or producing too soon or both. This results in poor flow with goods being pushed out rather than being pulled in.
The Waste of Unnecessary Motion.
Unnecessary motions refer to the importance of ergonomics for quality and productivity. If operators have to stretch, bend, pick-up, move in order to see better, or in any way unduly exert themselves, the victim is immediately the operator but ultimately quality and productivity.
The Waste of Unnecessary Inventory.
Parts, raw materials, work-in-process, inventory, supplies, and finished goods are all forms of inventory. Inventory is considered muda since it does not add value to the product.
Inappropriate Processing.
Processing muda consists of additional steps or activities in the manufacturing process. Conducting the work using inappropriate tools, methods, procedures or systems typically result in a waste of time or the production of defects. This is often a function of increasing complexity requiring a simplification of the process or a reduction in the variety of tools.
Excessive Transportation.
All forms of transportation are muda. This includes the use of forklifts, conveyors, pallet movers, and trucks. Excessive movement of information, materials, goods, products or people results in wasted time and effort and increases costs.
Waiting.
The muda of waiting occurs when an operator is ready for the next operation, but must remain idle. Periods of inactivity for information, goods or people resulting in poor flow and long lead times.
The Waste of Defects.
The last, but not least, of Ohno’s wastes is the waste of defects. Any error or variation from a standard in the production of a product, in the delivery of service or in the processing of paperwork or information is a defect. Costs associated with defects include the costs of detection or testing, reprocessing costs or cost of scrapping should reprocessing prove impossible as well as warranty costs and the costs associated with dissatisfied customers.
Lean as a Management System
As Mr. Ohno said, waste elimination was the starting point for Lean, not the end point. The relentless focus on waste elimination has produced a management philosophy and set of best practices that today encompass Lean and Lean Enterprise. Much of this is captured in the so called TPS House — the House of Lean
The TPS House
