Kanban is a visual workflow management system that originated from Toyota's manufacturing processes and has become an essential tool in the Lean Six Sigma Control Phase. The term 'Kanban' comes from Japanese, meaning 'visual signal' or 'card,' which reflects its core purpose of providing clear visu…Kanban is a visual workflow management system that originated from Toyota's manufacturing processes and has become an essential tool in the Lean Six Sigma Control Phase. The term 'Kanban' comes from Japanese, meaning 'visual signal' or 'card,' which reflects its core purpose of providing clear visual cues for process management.
In the Control Phase of DMAIC, Kanban serves as a powerful mechanism to sustain improvements and maintain process stability. The system uses visual boards divided into columns representing different stages of work, such as 'To Do,' 'In Progress,' and 'Completed.' Cards or sticky notes represent individual work items that move across the board as tasks progress.
The fundamental principles of Kanban include limiting Work in Progress (WIP), which prevents team overload and reduces bottlenecks. By setting maximum limits for each column, teams can identify constraints quickly and address them before they impact overall performance. This pull-based system ensures that new work enters the process only when capacity becomes available.
Key benefits of implementing Kanban in the Control Phase include enhanced visibility of workflow status, improved communication among team members, reduced cycle times, and better identification of process inefficiencies. The system promotes continuous flow and helps teams respond to changing priorities while maintaining quality standards.
Kanban boards can be physical boards placed in work areas or digital platforms accessible to distributed teams. The visual nature makes it easy to spot when processes deviate from expected performance levels, enabling quick corrective actions.
For Green Belt practitioners, Kanban provides a straightforward yet effective method to monitor and control improved processes. It supports the standardization of work procedures and helps embed lasting behavioral changes within the organization. When combined with other Control Phase tools like Statistical Process Control charts, Kanban creates a robust framework for sustaining the gains achieved during improvement initiatives.
Kanban System: A Complete Guide for Six Sigma Green Belt
What is a Kanban System?
A Kanban system is a visual workflow management method that originated from the Toyota Production System. The word 'Kanban' is Japanese for 'visual signal' or 'card.' It is a pull-based scheduling system that controls the flow of materials and information through a process by using visual signals to trigger action.
Why is Kanban Important in the Control Phase?
In the Control Phase of Six Sigma DMAIC, Kanban plays a crucial role because it:
• Maintains process improvements by creating visual controls that sustain gains • Reduces overproduction by producing only what is needed, when it is needed • Minimizes inventory costs through just-in-time delivery • Improves workflow visibility so teams can identify bottlenecks quickly • Enhances communication between upstream and downstream processes • Supports continuous improvement by making problems visible
How Does a Kanban System Work?
The Kanban system operates on several key principles:
1. Visual Signals (Cards) Physical or electronic cards represent work items. When a downstream process consumes an item, a Kanban card is sent upstream to signal the need for replenishment.
2. Work-in-Progress (WIP) Limits Each stage of the process has a maximum number of items allowed. This prevents overloading and maintains smooth flow.
3. Pull System Production is triggered by actual demand rather than forecasts. Work is 'pulled' through the system based on consumption.
4. Two-Bin System A common implementation where two containers hold inventory. When one is empty, it signals the need for replenishment while the second bin is used.
Types of Kanban
• Production Kanban: Authorizes the production of parts or products • Withdrawal Kanban: Authorizes the movement of parts between workstations • Supplier Kanban: Signals suppliers to deliver materials • Emergency Kanban: Used for defective parts or unexpected demand spikes
Calculating Kanban Quantity
The formula for determining the number of Kanban cards needed is:
Number of Kanbans = (Daily Demand × Lead Time × Safety Factor) / Container Size
Exam Tips: Answering Questions on Kanban System
1. Remember Key Characteristics Kanban is always a pull system, not a push system. If an answer suggests pushing work through based on schedules or forecasts, it is incorrect.
2. Focus on Visual Management Questions often test your understanding that Kanban relies on visual signals. Look for answers emphasizing visibility and signaling.
3. Know the Benefits Common exam questions ask about advantages: reduced inventory, improved flow, decreased lead times, and waste elimination.
4. Understand WIP Limits WIP limits are fundamental to Kanban. They prevent bottlenecks and ensure smooth workflow. Questions may ask how limiting WIP improves process performance.
5. Connect to Lean Principles Kanban supports just-in-time manufacturing and waste reduction. Expect questions linking Kanban to broader Lean concepts.
6. Recognize Application Scenarios When presented with scenarios, identify situations where demand variability exists, inventory needs reduction, or visual controls would benefit the process.
7. Differentiate from Push Systems Be prepared to distinguish Kanban (pull) from MRP or traditional scheduling systems (push). Pull systems respond to actual consumption; push systems respond to forecasts.
8. Remember the Formula Memorize the Kanban quantity calculation formula. Exam questions may require you to calculate the number of cards or bins needed.
Common Exam Question Formats
• Multiple choice asking for the primary purpose of Kanban • Scenario-based questions asking which tool would best control inventory • Calculation problems for determining Kanban quantities • True/false questions about pull versus push systems