The Kanban system, likened to the nervous system of lean production or Kaizen, regulates material flow in response to customer demand. Derived from the Japanese for “card” or “sign,” Kanban employs physical or digital cards to indicate production requirements. By synchronizing processes and connecting the value stream to customer demand, it curtails overproduction and waste. Kanban facilitates leaner, more agile production by enforcing efficient inventory control, promoting continuous improvement, and adhering to the pull production principle, where production is initiated only in response to actual demand, ensuring resources are allocated effectively and waste is minimized.
The Pull System and Waste Reduction
The Kanban system operates on the principle of pull production, where upstream processes only produce enough units to replace those withdrawn by downstream processes. Workers retrieve parts from preceding processes in needed quantities and timing, initiating with a customer order. This pull system mirrors a supermarket, where shelves are restocked as products are purchased, reversing the traditional “push” method of producing products based on an estimate of expected sales. Pull systems enhance production flexibility, minimizing overproduction and striving towards zero kanban, eliminating work-in-process inventory. The ultimate goal is a pure continuous flow, driven by customer demand, embodying the spirit of continuous improvement in lean production.
In determining Kanban implementation, consider whether to implement it plant-wide or in pilot areas. Implementing it solely in pilots may limit its effectiveness in integrating processes and connecting them to the customer. However, starting with a pilot can still expose production flow issues.
As Kanban reduces problems like long changeover times and machine downtime become apparent, requiring lean methods like 5S and SMED. If committed to a pull system with established lean practices, plant-wide Kanban integration synchronizes production processes, revealing hidden bottlenecks and realizing lean production goals.
Benefits of Kanban:
- Eliminate overproduction and unnecessary WIP inventory.
- Increase flexibility to respond to customer demand.
- Coordinate production of small lots and wide product variety.
- Have a simplified procurement process.
- Integrate all processes and tie them to the customer.