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Just-in-Time: A Practical Guide for Industry Professionals

Just-in-Time: Definition and Key Concepts
How to implement Just-in-Time management?

Just-in-Time (JIT) is a production management method that has transformed the industry by optimizing resources and minimizing waste. In this article, we’ll explore the fundamentals of JIT, its key tools, and the steps to implement it effectively.

Just-in-Time: Definition and Key Concepts

1. What is Just-in-Time?

Just-in-Time (JIT) is a production management method that aims to produce the necessary quantities of products at the precise moment they are requested by customers, without having excessive stocks of raw materials, components or finished goods.
It is one of the two pillars of the “temple” of Lean and therefore of the production system set up by Toyota. It is this principle that governs the operation of the pull stream.
In order to achieve this end goal, it is necessary to synchronize manufacturing activities well with the actual needs in order to achieve smooth process management.
We can then play on several axes to achieve this objective:

Inventory reduction
Reduction of delays
Optimization of the use of resources and production capacities
Process quality improvement

2. Principles of Just-in-Time

In order to successfully implement just-in-time, we can focus on two important principles:

Moving towards the elimination of intermediate stocks

Produce just the quantity demanded at the time it is requested

3. Just-in-Time Production Tools

We have seen what just-in-time consists of and two principles to remember, here are some tools to know and that I invite you to deepen if you want to set up JIT:
The “takt time” which synchronizes the customer’s consumption rate with the company’s production rate.

Value Stream Mapping (VSM) to visualize and identify key steps in the process.
SMED (Single Minute Exchange of Die) which aims to reduce tool change times.
The U-line that increases flexibility in the organization of workstations.
The spaghetti diagram: Used to visualize and optimize movement in a workspace.

How to implement Just-in-Time management?

In this second part, we will see how to implement just-in-time management step by step on your lines.

Step 1 - Include field actors in the process

The implementation of Just-in-Time often involves significant changes in the organization of work. To ensure that the decisions made during the implementation are sound and to facilitate this transition, it is essential to involve the relevant employees from the beginning of the process.
Quick tip: Using the RACI matrix can help clarify everyone’s roles and responsibilities.

Step 2 - Evaluate the flow using a VSM

As previously announced, Just-in-Time is based on the concept of pull flow, which applies to a series of interconnected operations.

Value Stream Mapping (VSM) will then be used to visualize and identify the key steps in the process. This step is important because it will serve as the foundation for the next steps in the implementation.

Step 3 - Calculate the "takt time"

As a reminder, the “takt time” is the average time between the start of the manufacture of a unit of product and the next.
To simplify, let’s take the example of a bakery that receives a customer every minute who buys a loaf of bread, this means that the Takt Time of this bakery should be less than one minute. Therefore, it must produce a loaf every 60 seconds, or less, to meet demand.
To align production with customer expectations, it is important to determine the “takt time”, which then defines our target production rate.

Step 4 - Identify the sources of waste (Mudas)

We will try here to identify the elements that can disrupt the efficiency of the flow. And you have to think about looking at the different categories: production of defects, waiting for operators or the
Once these Mudas have been identified, you must work on their elimination.

Step 5 - Establish work standards

Based on the “takt time” found in step 3, it will be important to establish work standards that will allow good repeatability and repeatability of the completion of tasks.

Let’s take an example: Let’s suppose, for example, that the creation of a part requires 4 successive manual operations lasting 60 seconds each.
If the “takt time” is close to 60 seconds (i.e. customers expect an average of one part to be delivered every 60 seconds), then the switchboard will provide for 4 operators, each in charge of one of the four operations.
If, on the other hand, the “takt time” is closer to 120 seconds, then the switchboard will provide for 2 operators, one in charge of successively carrying out the first two operations (which will take him about 96 seconds), the other in charge of carrying out the 3rd and 4th operations.

Step 6 - Analyze variability and establish buffer stocks

An ideal Just-in-Time organization aims to eliminate all intermediate inventory, but we are talking about an ideal case. A production line must also deal with inevitable variations (defects, delivery delays or equipment breakdowns, etc.). To manage these hazards, it is crucial to identify and quantify them. This can be achieved by analyzing historical data or by observing production over a representative period. Once variability has been measured, buffer stocks can be set up at strategic stages of the flow to absorb these fluctuations.

Step 7 - Collaborate with customers and suppliers

Often, a production or information flow depends upstream on raw materials or information from outside, and will generate a product or service that will also be passed on to an external customer.
To produce in “just in time”, it is then necessary to involve the players throughout the flow (and therefore suppliers and customers).

The key takeaway from Just-in-Time is a production management method that aims to produce the necessary quantities of products at the precise moment they are requested by customers, without having excessive stocks of raw materials, components or finished products.
To do this, Lean tools were used to achieve the final objective: to align the “takt time” with the production time of a part.

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