He-Niukazen, also known as visual production control or levelling, is a lean manufacturing concept that emerged after the Second World War in Japan as part of the Toyota Production System. The main goal of he-junka - or HejuNka - is to "level" or reduce fluctuations in production output throughout the day or even the week.

When a plant maintains a constant volume of products every hour, each unit remains in equilibrium, allowing for smoother workflow for employees and reduced strain on equipment. However, most manufacturers encounter variations in production needs - either in the volume or type of product - which can make efficient production lines look like jagged lines due to constant starts and stops.

Imagine working on an assembly line where production flows in a saw-tooth pattern. There are periods where employees have little to do, resulting in laid-backness, and then there is a long, frenzied stretch where they are working extremely hard, inducing fatigue and stress at the end of the shift.

By applying he-ju-nka techniques, factories can achieve stability in production. This not only saves on unnecessary labor expenses, but also keeps equipment in good working condition. Furthermore, stabilized manufacturing enables easier planning, optimization. Labor resources can be managed more effectively and, at the same time, create better opportunities for Quality analysis.