Toyota Production System

It is a manufacturing system developed by Toyota in Japan after World War II, which aims to increase production efficiency by the elimination of waste. The Toyota production system was invented and made to work, by Taiichi Ohno. While analyzing the problems inside the manufacturing environment; Ohno came to conclude that different kinds of wastes (non value added works) are the main cause of inefficiency and low productivity. Ohno identified waste in a number of forms, including overproduction, waiting time, transportation problems, inefficient processing, inventory, and defective products.

Figure  shows the Toyota Production System in detail. From this figure it can be seen that TPS is not only a set of different tools but it is the philosophy and integration of different tools and systems to achieve a common goal of waste reduction and efficiency improvement. Each element of this house is critical, but more important is the way the elements reinforce each other. Just In Time (JIT) means removing the inventory used to buffer operations against problems that may arise in production. The ideal of one-piece flow is to make one unit at a time at the rate of customer demand or Takt time. Using smaller buffers (removing the “safety net”) means t hat problems like quality defects become immediately visible. This reinforces Jidoka, which halts the production process. This means workers must resolve the problems immediately and urgently to resume production.

Stability is at the foundation of the house. While working with little inventory and stopping production when there is a problem causes instability and a sense of urgency among workers. In mass production, when a machine goes down, there is no sense of urgency because the maintenance department is scheduled to fix it while the inventory keeps the operations running. By contrast, in lean production, when an operator shuts down equipment to fix a problem, other operations will also stop immediately due to no inventory creating a crisis. So there is always a sense of urgency for everyone in production to fix problems together to get the machine in working condition and to run the production as soon as possible. 

If the same problem occurs repeatedly, management will quickly conclude that this is a critical situation and it should be cracked without any delay. People are at the center of the house, because it is only through continuous improvement that the operation can ever attain this needed stability. People must be trained to see waste and solve problems at the root cause by repeatedly asking why the problem really occurs. Problem solving should be on the actual site of the problem where everything is visible and practical also; this technique of problem solving is called Genchi Genbutsu.

In general TPS is not a toolkit. It is not just a set of lean tools like just-in-time, cells, 5S (sort, stabilize, shine, standardize, sustain), Kanban, etc. It is a sophisticated system of production in which all parts contribute to a whole. On the whole, its focus is on supporting and encouraging people to continually improve the processes they work on.