2-Box Principle

Short Description

The 2-box principle is the most powerful way of avoiding line stoppage due to material shortage. As the name implies, the fundamental idea is to provide two boxes of each material at the assembly line. Once a box is empty, it triggers the line feeder to supply new material to the line.

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Why do you have to implement a 2-Box Principle?

Avoid Line-stoppage due to Material Shortage

Mixed Model Production

The 2-box principle is the foundation of implementing a mixed model line

Reduce Inventory and Space

By defining the maximum line-side material storage by 2 boxes, all other material has to be moved to the supermarket or warehouse

Pull Process

Empty boxes act like a Kanban signal. Once material is consumed, the material handler has to refill whatever is consumed


As a dedicated number of full and empty boxes are inside your process, any deviation from that process becomes obvious


The 2-box principle is easy to be adapted and modified. Further products and models can be integrated easily

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without 2-Box Principle

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with 2-Box Principle

How do you implement a 2-Box Principle?

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As the empty box triggers the material handler to bring a new box to the material shelf, he has to place all the empties on a dedicated slot at the shelf.

To be able to place two boxes at the assembly line, the shelf must have at least two slots per part number with fixed locations and one additional slots for empty boxes. If the material handler’s cycle time is too high, increase from 2-boxes to 3-boxes.

Whenever the material handler removes an empty box from the line, he has to bring one full box to the line on his next cycle.

Enabler for:

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Training document – 2-Box Principle (pptx)
Training document – 2-Box Principle (PDF)