Notes
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The cumulative flow diagram (CFD) is a helpful tool for managing queues.
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The diagram uses:
- Time as its horizontal axis;
- Cumulative quantity as its vertical axis;
- Cumulative arrivals at a process as one variable;
- Cumulative departure as a second variable.
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The vertical distance between the arrival line and the departure line is work that has arrived but not yet departed, the size of the queue at a time.
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The horizontal distance between the lines tells the cycle time through the process for an item of work.
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The total area between these two lines tells the size of the queue.
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The slope of the arrival line tells the arrival rate of the queue.
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The slope of the departure line tells the capacity of the process of emptying the queue.
Cumulative Flow Diagram (CFD)