Just-In-Time is an organizing concept that aims to produce the right thing at the right time and at the right quality.
APICS gives the following definition of Just-In-Time : ” … production philosophy based on the systematic elimination of wastes and the continuous improvement of productivity“1.
Just In Time is a process and a way of thinking aimed at reducing waste. Associated with Jidoka, the JIT is one of the two pillars of the TPS house2.
Inspired by the work of Professor Shigeo Shingo and after a study trip to the United States, it is Taiichi Ohno who develops the JIT in the 50s. Sent to the United States to study Ford’s methods, he has been struck by the very important space reserved for the storage of parts.
He studied this fact, and concentrated his efforts on reducing the time between parts manufacture and assembly. This is the starting point of the doctrine of « Just In Time ».
This JIT system will be adopted by Toyota in 1962, but will not be immediately applied3 : the engineer Ohno has to face the reluctance of the workers, who are responsible for becoming versatile.
The Just In Time aims to provide customers with what they want, when they want and in the quantity they want !
Just In Time is based on the principle that we only produce once there is a demand expressed. This logic profoundly changes the organization of the business. We move from a logic called thrust to a logic drawn It is this reversal of point of view: the subordination of all activities of a company – including marketing, purchases, sales … – according to customer demand.
The pushed flow is the translation of a demand stronger than the capacity of production and one produces with the maximum capacities. This was the case at the beginning of the 20th century with, in particular, the history of the Ford T. The logic is to produce as much as the machines and the men can, without worrying about the actual demand of the customers. We are waiting for an .
A company that operates in Just In Time receives its raw materials only when an order is given by a customer. Customer demand is passed through the process starting with the back end of the process. The goal is for the customer to receive the right product, in good condition, at the right time, in the right place, in sufficient quantity and at the right price..
All this can be obtained by setting up :
- Buffer stocks at strategic locations.
- A replenishment system based on consumption.
- Increasing the frequency of deliveries.
- Reducing inventory levels.
- Increase the versatility of operators.
- More flexibilities.
- Design equipment and implement them in a flow logic.
Which flow to choose ?
Pull flow ou push flow does not fit all cases. An in-depth analysis of our situation must be made by examining :
- The context of the business.
- The degree of customization of the product.
- The time required by the market.
- Production specificities: costs, balancing …
- Standards in our sector: stock requirements for the pharmaceutical sector, for example.
One will then put in place a pushed or pulled flow, or a combination of both4, Part of the production is based on advanced planning while the other is managed as a pulled flow.
The 4 principles of Just In Time
Small batch production
La mastery of Takt Time
Training and Staff autonomy
Some examples in video
Just in time and …
JIT and Takt Time
Because of its definition, the JIT is in harmony with the customer demand represented by the Takt Time.
JIT and Flexibility
The Just In Time is based on 2 observations :
- Customer demand is becoming more variable H. FORD used to say “Anyone can have a Ford T of the color they want, as long as it’s black …. This statement is no longer possible today. Increasingly, customers want customized, almost custom-made products.
- The cost of storage is very important to produce a high flow induces a very large stock level. However, all that is in stock is not in cash: the stock is of the immobilized value that will have to be sold to find the treasury.
The cost of a stock
In addition to having blocked cash, a stock generates many ancillary costs :
- Il we “cost “the place and therefore the surface (to buy, maintain, heat ...)
- It may not be sold
- It gives the operator more time to find it when delivering
- It may be out of date by the time it’s sold
Setting up the JIT will allow to “lighten up” to make the company more flexible, more flexible. The reaction time will be shorter to manage the variability of the customer demand, the economic context, the technological evolutionss…
JIT and Zero Stock Strategy
Just In Time aims to reduce inventory levels, which is often called “Zero Stock Strategy“.
Implementation in this sense, many companies have abandoned the Just A Time claiming that Zero Stock is not possible for them and generates supply disruptions and delivery defects.
Rather than understanding “Zero Stock”, it must be understood that the Just In Time is rather a strategy of the “Stock at motst Just“.
JIT and Problem solving
The establishment of the JIT will highlight the problems of production. To illustrate this phenomenon, we use the image of the water level in the river :
- In the field, the more stock you have, the more your production is “secure”. Indeed, in order to be sure to meet customer expectations, teams produce inventory to overcome the problems of deliveries of parts, staff absences … The production manager, often objectified on the holding of deadlines delivery, is inclined to stock.
- This management will hide the problems. In the image of the water level, representing the level of stock, the more water you have in the river, the more water is “fluid”. But lowering the water level, highlights the rocks (representing the problems).
- JIT lowers water level and highlights hidden problems.
Source : R. Colin – Produire Juste-A-Temps en petite série, le guide
1 – S. Lamouri (1999) – Juste à temps et qualité totale
3 – R. Aïm (2013) – L’essentiel de la théorie des organisations 2013
4 – G. Balmana, R. Balmès (2001) – Modèles de gestion des flux : présentation et choix
Japan Management Association (1989) – Kanban Just In Time at Toyota
Y. Monden (2012) – Toyota Production System : An integrated approach to Just In Time