What is a Kanban system and how does it work in warehousing?
A Kanban system is a method of controlled material supply, originally derived from the Toyota production philosophy. It was developed by Taiichi Ohno to ensure a smooth, demand-driven material flow, entirely without unnecessary inventory or waiting times.
In warehousing, Kanban operates via so-called Kanban cards or digital signals that indicate when an item needs to be replenished. The basic idea: a storage location is only refilled once material has been withdrawn, the so-called pull principle.
Basic principles of the Kanban system according to Toyota and Taiichi Ohno
The Kanban system is based on three essential pillars:
- Pull principle instead of push logic: production and logistics are driven by consumption, not by stockpiling
- Visualisation: information on demand and inventory is made visible, traditionally through Kanban cards, today often through electronic systems
- Standardisation and continuity: Kanban is part of continuous optimisation
The goal is a smooth material flow that avoids unnecessary storage, overproduction, and bottlenecks.
The pull principle: how Kanban controls the material flow
In a Kanban-controlled warehouse, replenishment only takes place when a defined inventory is undershot, for example through withdrawal from a container. The system then issues a signal: please supply replenishment.
Replenishment is just-in-time and directly coupled to consumption. This keeps inventory costs low while minimising supply bottlenecks.
Difference between production Kanban and transport Kanban
Both are part of the same control loop, but govern different production stages.
What prerequisites are necessary to apply a Kanban system in the warehouse?
Not every item is suitable for Kanban. Prerequisites are:
- Continuous consumption (for example C-parts, screws, standard parts)
- Stable processes
- Manageable variety of variants
- Suitable containers and shelving systems
- Defined minimum and maximum stocks
Suitable items and containers for Kanban control
A functioning Kanban system requires that items and containers are consistently assigned and controlled. Ideal candidates are:
- Small and C-parts
- Wear materials
- Consumable items with predictable throughput
The containers must be standardised, whether stacking containers, visual storage bins, or pallets. It is decisive that they are clearly identifiable and traceable.
Handling demand fluctuations and variant variety
Kanban works best with steady demand. For fluctuating consumption or high variant variety, the following is required:
- Flexible adjustment of Kanban quantities
- Dynamic scaling of storage locations
- If necessary, a combination with other control methods (for example MRP)
Preventing bottlenecks in production and logistics
Bottlenecks arise when replenishment does not arrive in time. What helps:
- Transparent inventories
- Clear Kanban rules
- Reliable supplier integration
- Reserve containers (buffer Kanban) as emergency strategy
How can you practically set up and optimise a Kanban stock?
Design of an efficient shelving system for Kanban-controlled storage locations
A Kanban stock is usually set up in two stages: a supply container at the back, a withdrawal container at the front. As soon as the front one is empty, the rear one is used and a Kanban signal triggers the replenishment order.
The rule applies: each item has its defined storage location, every movement follows standardised rules.
Calculation of the optimal inventory for Kanban items
The Kanban inventory is derived from: consumption x lead time + safety buffer.
Example: if an item is needed at 100 units per day and replenishment takes 2 days, this yields a minimum inventory of 200 units. With a 20 % safety buffer: 240 units, split into 2 to 3 containers.
Transparency and dynamic adjustment of inventories
The Kanban system is not static. Changes in consumption, production capacity, or lead times require adjustment of Kanban quantities, this is part of continuous improvement.
Which types of Kanban signals exist and what is most efficient?
Manual Kanban cards: handling and practical implementation
The classical system is based on physical Kanban cards attached to containers. When the container is withdrawn, the card travels to the replenishment source.
Advantage: simple implementation without IT. Disadvantage: error-prone with many items or at high throughput.
Electronic Kanban system for more efficiency in logistics
Digital variants (for example via barcode scanning, RFID, or ERP connection) offer:
- Faster signal processing
- Automated replenishment control
- Better analysis and traceability
Especially in more complex warehouse systems, electronic Kanban is more efficient and scalable.
How does a Kanban system improve efficiency between warehouse and production?
- Inventories drop significantly because production and delivery only occur on demand
- Warehouse management becomes simpler, as replenishment is triggered automatically
- Production stoppages due to missing material are minimised
- Transparency increases, as it is visible at any time where demand exists
- Flexibility increases because the system can respond quickly to changes in consumption
Which challenges can arise when implementing a Kanban system?
Integration of suppliers into the Kanban system
Suppliers must:
- Accept Kanban signals
- Deliver just-in-time
- Organise container cycles
If the willingness or capability is missing, the system can falter.
Handling upstream processes and their optimisation
Upstream processes, for example internal manufacturing stages or purchasing, must also be synchronised. Misaligned upstream production planning can undermine the Kanban logic.