Lean thinking and practice are generic versions of the Toyota Production System (TPS) and the Toyota Way management system (2). Lean did not derive from theory but through observing practices at Toyota that were delivering superior performance in terms of product quality, efficiency (hours per car) and time to market for new products, leading Toyota to eventually become the largest car maker in the world.
The problem the founder of TPS, Taiichi Ohno, was trying to solve in the 1950s was how to build several different products on the limited equipment that Toyota could afford at that time. Instead of resorting to producing in batches he carried out many pioneering experiments to build an integrated production system that was able to make a variety of products in single-piece flow in line with demand. This challenged the assumptions that there is a trade-off between quality and productivity and that bigger batches lead to economies of scale and lower costs. His experiments also led to the development of many new tools, such as Kanban pull systems and SMED quick changeovers (3). Ohno also built on Toyota's Jidoka system for making abnormalities visible immediately, invented in the 1930s.