Integral Logistics Management — Operations Management and Supply Chain Management Within and Across Companies

6.1.1b The Toyota Production System (TPS): Just-in-Time and Jidoka

Intended learning outcomes: Produce an overview on just-in-time, Jidoka, lean production and a lean enterprise. Differentiate between the conventional view of inventory and the Japanese view.

Continuation from previous subsection (6.1.1)

TPS encompass a set of methods, techniques, and tools to increase quality and speed without increasing “muri” or decreasing productivity. Jidoka and Just-in-time are the two pillars of the TPS. Both pillars encompass methods, techniques, and tools for reducing all 3Ms.

The Jidoka concept comprises approaches and techniques for immediately halting production when abnormal conditions occur. Jidoka means “automation (Jap. 自動化) with manlike sensors,” which is rendered by the artificial term “autonomation” (Jap. 自働化).[note 603].

Jidoka therefore is aimed at the elimination of production of defective products by building quality into the production process. This way of thinking stems from 1902, when Sakichi Toyoda, who later founded the Toyota Motor Corporation, patented a device to stop a weaving loom as soon as a thread broke. This prevented the weaving of defective fabrics and allowed operators to fix the problem itself, strand breakage, as soon as possible. Section 18.2.5 shows some of the techniques of the Jidoka concept.

The just-in-time (JIT) concept encompasses a certain set of approaches, methods, and techniques for planned elimination of all waste. The primary elements are to have only the required inventory when needed; to improve quality to zero defects; to reduce lead times by reducing setup times, queue times, and lot sizes; and to incrementally revise the operations themselves. Cf. [ASCM22].

The just-in-time concept thus increases the potential for short delivery lead times for all types of production and for many service lines of business.[note 603]

The terms stockless production or zero inventories as synonyms for just-in-time are misleading and thus not used in this work. After all, the Kanban technique does require inventory in buffers at all production structure levels. The misunderstanding resulting from this misrepresentation is probably also responsible for the fact that JIT was frequently understood and applied incorrectly and that, finally, the new catchword “lean” took the place of the term JIT.

Lean production emphasizes the minimization of the amount of all required resources (including time) for the various activities of the company (cf. [ASCM22]). It involves identifying waste (see definition above) and eliminating them.

A lean enterprise applies the principles of lean production to all areas within the organization.

Since the time it was introduced, the philosophy of lean production [WoJo07] has often been taken to extremes. It served as a convenient justification for firing and not replacing staff members. Some people postulated polemically that the contradictory objectives of the company, as outlined in Section 1.3.1, could be resolved. They did not consider at all explicitly the target area of flexibility, for its objectives are usually long term in nature. The customer does not readily recognize that the building of such competencies is value-adding. This view led to company anorexia and resulting paralysis. It proved to be wrong at the very latest when companies became no longer capable of achieving innovations.

The JIT concept originally introduced by the Japanese corresponds most extensively with the current concept of “lean,” which once again gives the target area of flexibility the consideration that it deserves. See here also Section 1.3.3. In any case, the aim is still to reduce useless effort, or waste. As to reducing inventory, Figure shows the change in view of inventory that took place between 1970 and 1990.

Fig.        Alternative views of inventory.

High inventory acts as a high water level (light background) in a lake that has shallows and shoals (dark background). If the water level falls, the obstacles will be felt and must either be removed or avoided through a change in course. Reducing inventory exposes problems that must be corrected by means of appropriate concepts. Japan gained this insight early on (see also [Suza12]).

Course section 6.1: Subsections and their intended learning outcomes