Visit Kanban is an operational and visual tool for Lean Management, which takes its name from the two Japanese characters : Kan (map or visual signal) and Ban (table). Developed by Toyota, it is the key element for implementing the Pull System in an environment of Series Production.
In-depth definition : Kanban is a signalling system which regulates production and the supply of materials. Its role is to trigger the manufacture or delivery of a part only when the downstream workstation (the internal customer) needs it. The Kanban card or signal circulates between workstations: when the stock of a component reaches a predefined minimum level (the replenishment point), the card is sent to the upstream workstation (the internal supplier) to authorize production or delivery of the exact number of parts consumed. The aim is to strictly limit the work in progress (WIP - Work In Progress) and avoid overproduction (the most dangerous waste, Muda).
The Fundamental Principles and Golden Rules of Kanban
For a Kanban system to be effective and support the’Operational Excellence, four rules must be scrupulously observed:
- Produce/Deliver only what is Withdrawn : The upstream station must only produce the parts indicated by the kanban signal. This ensures that production is drawn by real demand, not push through theoretical planning (MRP).
- One Kanban per container (or batch): Each container or batch of parts must have an associated Kanban card. The return of this card is the replenishment signal.
- No Part Without Kanban : No part may be produced, transported or stored unless it is attached to a Kanban signal. This rule disciplines the workshop and ensures strict control of the WIP.
- Check Quality at each Stage: Kanban makes the workshop very sensitive to problems of Quality. If a fault occurs, the downstream station stops firing, and the problem immediately recurs, forcing the downstream station to stop firing. Root Cause Analysis (RCA) and the’Continuous Improvement (KAIZEN) at the upstream station.
Kanban and Industrial Performance
The implementation of Kanban by Industrial Engineering is a prerequisite for transforming a Flux Poussé into a system of Pulled Flow performing :
- Drastic inventory reduction : Kanban is designed to run the business with the minimum safety stock necessary to cover variations in demand and replenishment lead times. This frees up capital (working capital) and space.
- Identifying Problems (Bottlenecks) : By limiting WIP, Kanban makes problems visible. If a Bottleneck slows down a step, the upstream queue quickly empties, and the other stations stop, clearly exposing the source of the blockage (one of the main objectives of the Visual Management).
- Lean management : The company is constantly looking for ways to reduce the number of Kanban cards, and therefore inventory. Each successful reduction exposes the next problem or waste to be eliminated, fuelling the cycle. PDCA.
Digital Kanban (e-Kanban) and Industry 4.0
In the age of Industrial Digitization, Kanban has evolved:
- e-Kanban : Physical cards are replaced by electronic signals. Barcode scanners or sensors, for example IoT detect consumption and send an automatic signal to the system MES (Manufacturing Execution System) or the’ERP (Enterprise Resource Planning) to generate a production or purchase order.
- Kanban and AI: Visit Machine Learning can help dynamically optimize lot size (the number of parts per kanban) and trigger point to better respond to variations in demand and supply. Takt Time.
The essence of Kanban remains the same: visualize the flow, limit WIP, and drive production by real demand. It is the control mechanism that gives the plant its flexibility and efficiency. Pulled Flow.