JIT is a manufacturing philosophy involving an integrated set of procedures/activities designed to achieve a volume of production using minimal inventories.
A highly coordinated processing system in which goods move through the system and service are performed, just as they need.
- Evolved in Japan after World War II, as a result of their diminishing market share in the auto industry.
- Founded by Taiichi Ohno, a vice President of Toyota
Just in time – Philosophy of complete elimination of waste
“Just-in-Time” means making “only what is needed, when it is needed, and in the amount needed.” For example, to efficiently produce a large number of automobiles, which can consist of around 30,000 parts, it is necessary to create a detailed production plan that includes parts procurement. Supplying “what is needed, when it is needed, and in the amount needed” according to this production plan can eliminate waste, inconsistencies, and unreasonable requirements, resulting in improved productivity.
In the TPS (Toyota Production System), a unique production control method called the “kanban system” plays an integral role. The kanban system has also been called the “Supermarket method” because the idea behind it was borrowed from supermarkets. Such mass merchandizing stores use product control cards upon which product-related information, such as a product’s name, code and storage location, are entered. Because Toyota employed kanban signs for use in their production processes, the method came to be called the “kanban system.” At Toyota, when a process refers to a preceding process to retrieve parts, it uses a kanban to communicate which parts have been used.
Evolution of the kanban through daily improvements
Through continuous technological improvements, the kanban system has evolved into the “e-kanban,” which is managed using IT methodologies and has increased productivity even further.
Taiichi Ohno (a former Toyota vice president), who promoted the idea of Just-in-Time, applied this concept, equating the supermarket and the customer with the preceding process and the next process, respectively. By having the next process (the customer) go to the preceding process (the supermarket) to retrieve the necessary parts when they are needed and in the amount needed, it was possible to improve upon the existing inefficient production system. No longer were the preceding processes making excess parts and delivering them to the next process.
In relation with the logistics terms, i can said that Toyota use Just-in-time production in a good way because relies on finely tuned processes in the assembly sequence using only the quantities of items required, only when they are needed. Imagine a process designed to produce six different types of product, where the total weekly demand for the range of products varies up and down by 25%, and the daily mix of product types is continuously changing. A planning challenge, but also a typical scenario in many types of business in which the process (manufacturing or otherwise) has to continuously respond to demand. Toyota Production System has responded to this reality of life by developing an approach that can meet the challenge in an efficient, cost-effective way.
Just-in-time offers a smooth, continuous and optimised workflow, with carefully planned and measured work-cycle times and on-demand movement of goods, reduces the cost of wasted time, materials and capacity. Team members can concentrate on their tasks without interruption, which leads to better quality, timely delivery, and peace-of-mind for Toyota’s customers.