Heijunka (Production Leveling)
Heijunka smooths production volume and mix over time to eliminate peaks and valleys. It creates a steady, predictable flow that reduces waste and stress throughout the value stream.
Heijunka (Japanese: 'leveling') distributes production evenly across the available time rather than producing in large batches. Instead of making 500 units of Product A on Monday and 500 of Product B on Tuesday, Heijunka produces a mix of both every day -- or even every hour.
The benefits cascade through the entire value stream: Suppliers receive steady, predictable orders instead of erratic spikes. Internal processes run at a constant pace. Finished goods inventory drops because products are made closer to when they are needed.
Heijunka requires short setup times (SMED) to be practical. If changeovers take hours, frequent switching between products is not feasible. That is why SMED is often a prerequisite for leveled production.
In practice, Heijunka is often implemented with a Heijunka box -- a physical or digital schedule that assigns specific products to specific time slots. This creates a repeating pattern (pitch) that everyone in the process can follow.
Practical Example
A furniture manufacturer produces 3 product lines. Previously: Batch production with week-long runs per product. After Heijunka: Each product is made daily in small quantities. Finished goods inventory drops from 3 weeks to 4 days. Delivery time to customers improves from 18 days to 6 days.
How Leanshift Helps
Leanshift's process recording captures actual production sequences and changeover frequencies. This data reveals current batch patterns and helps design the optimal Heijunka schedule for leveled production.
Frequently Asked Questions
Does Heijunka work with high product variety?
Yes, but it requires short changeover times. Start leveling with your highest-volume products first, then expand as setup times decrease. Even partial leveling delivers significant benefits.
Is Heijunka the same as a production schedule?
No. A traditional schedule optimizes for machine utilization (large batches). Heijunka optimizes for flow and customer responsiveness (small, mixed quantities). The goals and results are fundamentally different.
What is a Heijunka box?
A visual scheduling tool with rows for product types and columns for time intervals. Kanban cards are placed in slots to define what is produced when. It makes the leveled schedule visible and manageable for everyone.
Related Terms
Takt Time
Takt time is the pace at which a product must be completed to meet customer demand. It is determined by the market, not by the machine.
SMED (Single Minute Exchange of Die)
SMED is a method for drastically reducing setup times. Goal: Every changeover in under 10 minutes -- in the single-digit minute range.
Kanban
Kanban is a visual pull system that controls the flow of work and materials using signal cards. It limits work in process and ensures that production only happens when there is actual demand.