Toyota Production System

The Toyota Production System (TPS) is an integrated socio-technical system, developed by Toyota, that comprises its management philosophy and practices. The TPS organizes manufacturing and logistics for the automobile manufacturer, including interaction with suppliers and customers. The system is a major precursor of the more generic "Lean manufacturing." Taiichi Ohno, Shigeo Shingo and Eiji Toyoda developed the system between 1948 and 1975.

Originally called "Just In Time Production," it builds on the approach created by the founder of Toyota, Sakichi Toyoda, his son Kiichiro Toyoda, and the engineer Taiichi Ohno. The founders of Toyota drew heavily on the work of W. Edwards Deming and the writings of Henry Ford. When these men came to the United States to observe the assembly line and mass production that had made Ford rich, they were unimpressed. While shopping in a supermarket they observed the simple idea of an automatic drink resupplier; when the customer wants a drink, he takes one, and another replaces it. The principles underlying the TPS are embodied in The Toyota Way.

Goals
The main objectives of the TPS are to design out overburden (muri) and inconsistency (mura), and to eliminate waste (muda). The most significant effects on process value delivery are achieved by designing a process capable of delivering the required results smoothly; by designing out "mura" (inconsistency). It is also crucial to ensure that the process is as flexible as necessary without stress or "muri" (overburden) since this generates "muda" (waste). Finally the tactical improvements of waste reduction or the elimination of muda are very valuable.

There are seven kinds of muda that are addressed in the TPS:

over-production
motion (of operator or machine)
waiting (of operator or machine)
conveyance
processing itself
inventory (raw material)
correction (rework and scrap)

The elimination of muda has come to dominate the thinking of many when they look at the effects of the TPS because it is the most familiar of the three to implement. In the TPS many initiatives are triggered by mura or muri reduction which drives out muda without specific focus on its reduction.

Origins
This system, more than any other aspect of the company, is responsible for having made Toyota the company it is today. Toyota has long been recognized as a leader in the automotive manufacturing and production industry.

Toyota received their inspiration for the system, not from the American automotive industry (at that time the world's largest by far), but from visiting a supermarket. This occurred when a delegation from Toyota (led by Ohno) visited the United States in the 1950s. The delegation first visited several Ford Motor Company automotive plants in Michigan but, despite Ford being the industry leader at that time, found many of the methods in use to be not very effective. They were mainly appalled by the large amounts of inventory on site, by how the amount of work being performed in various departments within the factory was uneven on most days, and the large amount of rework at the end of the process.

However, on a subsequent visit to a Piggly Wiggly, the delegation was inspired by how the supermarket only reordered and restocked goods once they had been bought by customers. Toyota applied the lesson from Piggly Wiggly by reducing the amount of inventory they would hold only to a level that its employees would need for a small period of time, and then subsequently reorder. This would become the precursor of the now-famous Just-in-Time (JIT) inventory system.

While low inventory levels are a key outcome of the Toyota Production System, an important element of the philosophy behind its system is to work intelligently and eliminate waste so that inventory is no longer needed. Many American businesses, having observed Toyota's factories, set out to attack high inventory levels directly without understanding what made these reductions possible. The act of imitating without understanding the underlying concept or motivation may have led to the failure of those projects.