"Lean" was developed by Toyota for the automotive industry. The developer of the production system we know today as TPS was Taichi Ohno. He realized that the process of producing automobiles, from receiving orders, to production, to delivery and invoicing was taking far too long and a lot of non-value added work was being done. The son of the company's founder, Toyoda, had already begun to "streamline" the manufacturing process during wartime in the middle of the century and to cope with the difficult conditions by "just-in-time" delivery.
Taichi Ohno developed these ideas further after the Second World War. He got his inspiration from the USA and Ford's assembly line production. He finally recognized the added value of this type of production, but also saw that the "push" principle used there was not particularly well suited. With these prerequisites and influences in mind, he developed and perfected the TPS over the years, which made Toyota the largest car manufacturer in the world.
The actual term "lean" was not coined until the 1990s. The two American economists James P. Womack and Daniel T. Jones investigated the superior TPS and worked up the principles scientifically. The term "Lean" and the implementation in practice through "Lean Production" developed as a result of this reappraisal of the TPS.
In the course of the spread of lean production in the automotive industry, other economic sectors have also dealt with the topic and made their processes and workflows "lean". As a result, "lean management" has become an overarching management philosophy that is now applied in all sectors of the economy.
The book "Lean Thinking" by Womack & Jones not only coined the term Lean, but also the 5 principles behind Lean. Although various sources and works have often expanded on the 5 Lean principles, generally only these 5 principles are defined for Lean:
What does the customer really want and what is he really willing to pay money for? You should ask yourself this question again and again in order to always be able to work in a customer-centric and needs-oriented manner that is geared to the needs of the customer.
Once the customer added value has been defined, the next step is to analyze and optimize the underlying process. For this purpose, the activities are divided into three categories: "value-adding", "necessary" and "waste". Process optimization is aimed at maximizing the value-added work, minimizing the necessary activities and eliminating waste.
The optimized process should be kept in a continuous flow and ensure a smoothed sequence. Buffers and intermediate storage should be avoided, as well as uneven degrees of utilization.
Production should be demand-driven and on demand! This means that the flow of information runs against the flow of production and the last "station" thus requests the performance of the previous one.
Kaizen is Japanese and means "continuous, never-ending improvement". Because nothing is so good that it can't be improved even further. According to Lean, this principle should be applied to everything. So you should also go through and question the four previous Lean principles again and again.
Here you will find all details about the Five Lean Principles.