Kanban vs. Heijunka: Demystifying Visual Workflow Management (Enhanced Dual-Card Loop & Cell-Level Optimization)
Ever feel like your production cells are constantly scrambling, or that inventory shortages are derailing your operations? You're not alone. In today's lean manufacturing environments, mastering visual workflow management at the cell level is crucial. That's where Kanban and Heijunka, working in tandem, can transform your operations.
Kanban: Cell-Level Inventory Control with Dual-Card Loop
Imagine each production cell equipped with its own Kanban board, ensuring real-time inventory visibility and replenishment, enhanced by a dual-card loop.
* Decentralized Kanban: Each cell manages its material flow using a dedicated Kanban board, tailored to its specific needs.
* Dual-Card System: Each inventory bin is associated with two identical Kanban cards.
* Both cards are dated and placed in the "Turned-In" slot when the bin is emptied.
* Due Date Assignment: Both cards are then dated with the expected delivery date, based on lead time.
* Card Separation:
* One card remains on the cell's Kanban board, placed in its corresponding due date slot, providing a clear visual of expected inventory arrival.
* The second card is sent back to the first process (e.g., the upstream supplier or the material handling department).
* Upstream Signaling: This second card acts as a direct signal, notifying the upstream process that more inventory is needed. It initiates the replenishment cycle.
* Cell-Level Tracking: The card that remains at the cell allows the team to visually track the expected arrival of the needed materials.
* Constraint/Late Slot: If either of the two cards due dates are missed, the card is moved to the constraint/late slot.
* Management Oversight and Problem Solving: Team leads, group leads, and management monitor the "Constraint/Late" slot for issues. They perform "5 Whys" analyses, update material information, redate the card, and return it to the board.
This dual-card loop system provides:
* Redundant signaling, minimizing the risk of missed replenishment.
* Clear visual tracking of expected inventory arrivals at the cell.
* Direct communication with upstream processes.
* Enhanced constraint management.
Production Scheduling: Level Loading at the Cell Level
Now, let's introduce cell-level scheduling boards, built on Heijunka principles, to ensure optimal production flow.
* Cell-Specific Scheduling: Each cell utilizes a scheduling board with "Current," "Current +1," "Current +2," "Current +3," and "Current +4" columns.
* Proactive Pulling: Cell operators proactively pull work from "Current +3" and "Current +4" into earlier periods, maintaining a consistent workload.
* Leveling "Lite" Days: By analyzing the scheduling board, operators identify "lite" days (e.g., days with fewer orders). They then pull forward orders to level out production, ensuring consistent output (e.g., maintaining 200 units per day).
* Spike Management: When anticipating order spikes, operators use the scheduling board to level load the increased demand across multiple days. This prevents overwhelming the cell on a single day and minimizes the need for overtime.
* Optimal Production: Maintaining a consistent daily output ensures that the cell is working at optimal levels.
Key Differences: Cell-Level Focus
* Kanban at the cell level focuses on localized inventory management and rapid replenishment using a dual card system.
* Scheduling boards at the cell level focus on proactive production leveling and spike management.
Real-World Application: Optimized Cell Performance
Imagine a manufacturing facility where each production cell has its own Kanban and scheduling boards. This decentralized approach empowers cell operators to:
* Maintain optimal inventory levels.
* Ensure consistent production flow.
* Proactively manage order spikes.
Tips for Implementation:
* Provide thorough training to cell operators on both Kanban and scheduling board management.
* Encourage regular cell-level meetings to review board status and adjust production schedules.
* Ensure clear communication between cells and material handling teams.
* Make sure that the Kanban board and the Heijunka scheduling board are located near one another.
* When using kanban for inventory management, make sure all team members are trained on how to properly update the kanban board. This will ensure that all information is accurate and up to date. Also, make sure that the kanban board is located in a central location where all team members can easily access it.
Conclusion:
By implementing cell-level Kanban with a dual-card loop and scheduling boards, you can achieve a highly responsive, efficient, and optimized production environment. This approach empowers your teams, reduces waste, and enhances overall operational excellence.
#LeanManufacturing #Kanban #Heijunka #VisualManagement #ProductionOptimization #OperationalExcellence #CellularManufacturing #InventoryControl
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