What is lean manufacturing? Lean Manufacturing is "A systematic approach to identifying and eliminating waste through continuous improvement by flowing the product at the rate of demand of the customer."

James P. Womack and Daniel T. Jones defined a set of five basic principles that characterize a lean enterprise In their 1996 book "Lean Thinking"

Specify value from the standpoint of the end customer by product family

Identify all the steps in the value stream for each product family, eliminating every step and every action and every practice that does not create value

Make the remaining value-creating steps occur in a tight and integrated sequence so the product will flow smoothly toward the customer

As flow is introduced, let customers pull value from the next upstream activity

As these steps lead to greater transparency, enabling managers and teams to eliminate further waste, pursue perfection through continuous improvement

Lean is about doing more with less: Less time, inventory, space, people effort, and money. Lean is about speed and getting it right the first time.

From postwar period to the 73-75 oil crises the West enjoyed a period of steady growth. During this period, the needs were bigger than on offer, and for industries, priority was to produce than sell. For Japan, the objective is to catch-up with the US, at least in some businesses, like automotive industry. Japan's industry could not follow and compete on the Ford Production Model basis, so industries sought new and original ways, adapted to their constraints. Market was eager to buy, and what ever was manufactured was sold. These conditions pushed to maximize production. Yet Japan still having limited natural resources, it could not increase production by multiplying productive investments. These local conditions explain the birth of methods based on waste elimination (saving scarce resources) and maximizing production (hence sales!!) and productivity (sell more while saving resources)

Tilting of economies - The paradigm shifted from penury (high demand) to economy of offer (excess offer vs. low level of demand) in the 70s. Offer exceeded demand on the double effect of global competition and consumption slowdown. Ford's production model favors massive production of goods with few variants. This model was adapted to huge needs of cheap products, made available to the masses during the oil crisis period (1973-1975) and afterwards. A consequence of the oil crisis was the increasing of raw material and production costs, while the fears linked to the crisis slowed consumption and shifted customer's expectations: •Ordinary products have to be cheaper, as customer buy the lowest price •Equipment and expensive goods have to show durable, robust and most of all suit quality expectations •other products must bring to the buyer an esteem value (pleasure, exclusive features…). In a very competitive economy, the cost management appears as a priority. Yet the Japanese have accumulated years of experience and have a new production model handy, which matches the new paradigm: the TOYOTA Production System.

In Japan, for the domestic market, the production system was not the Ford model (economies of scale), but an original one seeking to give clients a broader choice; • More models • More colors • Customization. This Production System brings shorter series: • Shorter (shelf) life cycle for models • Multiplication of manufacturing batches within the life cycle. Hence, changeovers multiply and shorter shelf life imposes a wise, waste free usage of available manufacturing time.

The New Paradigm - The new, actual context shows increased demand for customization and specific customer expectations, in a globally growing offer. Except for few products, mass production is changed to small batches with shorter life cycle. The challenge for industries is no more to mass manufacture at low cost, but propose products (and services) which suit the client's taste, at a price he / she is ready to pay. Hence more, with the number of competitors (alternative sources for customers), the clients are no longer ready to wait to get their whishes fulfilled. They rather seek satisfaction elsewhere. Manufacturers can no longer push merchandises they decide to design, manufacture and sell towards the market, but have to respond in a economic and quick manner to spot demand, triggered (pulled) by the market.

In the new paradigm, new ways of thinking operations and marketing raise. Lean manufacturing, linked to Toyota's production system and further to what is called "Toyotism", is already widespread. Tools and methods made Japanese industries a global success. They deeply impacted the decades 1980 – 1990 in the West. Lean manufacturing spreads from workshops and became global, lean thinking, Thanks to authors like Goldratt (theory of constraints) and Womack & Jones (lean thinking). The word “lean” was coined by James Womack in the early 1980’s.