Heijunka

The Heijunka concept was developed after World War II at the Japanese Toyota Motor Company and is still used today not only in the automotive industry, but also in the food and processing industry. Heijunka is also part of the Toyota Production System.

Heijunka comes from a Japanese word meaning “leveling.” In the concept of Lean Management, this term means leveling production to achieve a uniform, even production rhythm and avoid overloading.

Causes of production inequality:

• Different products require different steps, so the process can get longer or shorter.
• Different activities take different amounts of time.
• Each employee has a different productivity level – manual tasks will take more time for some employees and for others they will take less time.
• Each machine is different and the pace of operation will vary.
• Employees tend to put off tasks they don’t like doing until later. This, on the scale of a complete task pool, pushes some items beyond their expected completion date.
• Customer orders tend to be diverse and unstructured (variable demand).
• Stock shortages can force changes in production schedules.

Why is it important to level production?

As we have already mentioned, the implementation of Heijunka protects the production process from overloading (eliminates muri) and allows to improve the production flow. By leveling production, the product run time is reduced, quality and process efficiency are improved.

Heijunka is also a great tool for efficient use of available resources and production capacity, despite demand variability. Leveling production realistically reduces lead times and reduces inventory, which is one of the 7 types of waste in companies.

All of this also indirectly increases customer satisfaction and better ability to meet customer needs.

In the Logistics course on our platform you will find information on how to level production in practice.

Example of leveled production

Before:

After:

Heijunka and one piece flow

Heijunka’s goal is to have a flow of one piece along the production line. The one-piece flow requires a very flexible production line, a state-of-the-art system and modern machine park. All this generates high costs. To reconcile the concept of one-piece flow with Heijunka, companies choose to produce in small batches based on actual customer demand. This way step production, which is the enemy of Heijunka, is prevented.

Heijunka conditions

Heijunka functions best in an environment characterized by qualities such as flexibility, predictability and stability.

Advantages and disadvantages of Heijunka

Heijunka is a tool that has many advantages. Among the biggest benefits we can mention:

• Speeding up production (reducing lead times).
• Load balancing between operations in production.
• Reducing the 3 basic types of waste: muda, mura and muri.
• Increasing flexibility and efficiency.
• Avoiding step production (due to seasonality or trend).
• Using available resources efficiently.
• High level of stability of enterprise development.
• Reducing work routine – employees perform more varied operations than in large-scale mass production.
• Ability to respond more quickly when quality problems arise (and potentially less waste due to poor quality).

However, it is not a tool without disadvantages. You need to know that the implementation of Heijunka involves:

• maintaining constant discipline, which can be stressful for employees.
• putting pressure on dynamic decision-making and quick problem-solving.
• extremely efficient and frequent machine changeovers (knowledge of SMED is essential here).
• increased responsibility of suppliers (delivery delays are not allowed, Just in Time applies).
• more precise production planning and quick response to customer needs.