What is Heijunka and How Does Production Leveling Improve Factory Flow?

What is Heijunka?

Heijunka is a Lean manufacturing method used to level production volume and product mix over time.

Instead of allowing demand fluctuations to create highly uneven production schedules, the goal is to create a smoother and more predictable workload.

In simple terms

Imagine customer demand requires:

• Product A → 600 units/week
• Product B → 300 units/week
• Product C → 100 units/week

A factory could produce all of A first, then B, then C.

Heijunka encourages a more balanced sequence, such as producing smaller quantities of different products repeatedly.

Simple Example

Instead of:

AAAAAA → BBB → C

A leveled sequence could look more like:

A → A → B → A → C → A → B → A → A → B

The exact sequence depends on demand, batch size, changeover time, and available capacity.

Why It Matters

Uneven production can create:

• Large WIP fluctuations
• Material shortages
• Overtime
• Uneven manpower requirements
• Machine overload
• Long waiting times

Production leveling aims to make the workload more stable.

Important Insight

Heijunka does not mean producing the same quantity of every product.

It means distributing production according to the required product mix and demand, while considering the factory’s practical constraints.

How to Apply It

• Analyze customer demand.
• Determine required product quantities.
• Calculate available capacity.
• Understand changeover requirements.
• Create a suitable production sequence.
• Monitor actual production against the leveled plan.

Benefits

• Smoother production flow
• More stable workloads
• Better inventory control
• Reduced production variation
• Improved resource planning
• Better response to demand changes

Practical Insight

A production schedule should not only answer:

“What should we produce?”

It should also consider:

“How can we sequence production so that the factory remains stable?”

That is the real value of production leveling.