Level out the workload (Heijunka)
Toyota Motor Corporation, 1999-2005
Heijunka is a Japanese word that has been frequently used in Toyota’s production system – and many other organizations that allow production systems that impact so much that inspire another to start a lean transformation – and it is ussually tranlated as «levelling». This concept implies that levelling the flow of the production over a concrete period of time, is very helpfull when it comes to eliminate production costs and deliver what is needed to your customer, and only what he needs, at the exact moment that he needs it.You can not apply heijunka without reducing waste.
These concepts are found very often at the Toyota Way manual, which defines its mindset and point of view about the process to level out the workflows.
As a result, Toyota managers and employees use the Japanese term Muda when talking about waste. But there are two others “Ms” that are just as important: Muri and Mura.The “3Ms: Muda, Muri, Mura”, are integrated in one system. In fact, focusing only on the eight types of Muda can be counterproductive. The Toyota Way and Toyota Production System refer to the “elimination of Muda, Muri, Mura”. The 3Ms are:
- Muda: Non-value adding actions. The most familiar M includes the eight types of waste: overproduction, inventory, overprocessing, defect, transport, motion, waiting, non-utilized talent.
- Muri: Overburden. The Mura forces people and technology to exceed the level of what is tolerable. Overloading people and technology results in problems of quality, stability and safety.
- Mura: Unevenness. Usually the consequence of the other two Ms. All the unevenness of delivery is not always the result of changing demand but of internal wastage resulting from Muda and Mura. This unevenness leads to having human equipment and technology available far beyond the real needs of the demand.
Heijunka as a key to lean transformation
In conclussion, Toyota is an example for lean manufacturing system in which production responds to demand. That is why many organizations are inmersed in a lean transformation, seeing Toyota’s success in perduring in time and creating value for its customers, which has led to the japanese multinational to be one of the largest on the automotive industry.
As we mentioned in the latest principles, the workflow needs to be continuous, and levelled-out when possible (heijunka). This not always easy but when applied correctly, limited lots allow greater flexibility and agility — which is fundamenta at a lean manufacturing system. Also, reducing inventory helps reduce, or even eliminate waste, and identify problems in order to solve them inmediately.