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200 Processing
Transportation and material handling
Kanban model
A Kanban system is modeled in ExtendSim by monitoring the queues between machines and having that information regulate processing. To do this, set the Queue block capacity to the number of kanbans and connect the F (full) output from the block back to the preceding Activ- ity’s SD (shutdown) output connector. When the queue has remaining capacity, its F connector will output 0 (zero) and the preceding Activity block will be authorized to produce parts. If the Queue block is full, its F connector will output 1 and the preceding machine will be shut down until the queue length is reduced.
Kanban model
If you run this model with animation on, the Activity blocks will be struck through in red while they are shut down.
Transportation and material handling
The following Item library blocks are used to represent transportation and material handling: • Transport
• ConveyItem
• Resource Item
The Convey Item and Transport blocks represent ovens, conveyors, and so forth to provide fixed-path routes with a specified travel time for items. The Resource Item and Transport blocks are used with the Batch and Unbatch blocks to simulate AGVs and other independently moving vehicles.
☞ The models discussed in this section can be found in the Examples\Discrete Event\Process- ing\Material Handling and Transportation folder.
Travel time
In a discrete event model, items move from block to block as dictated by the connections. These connections indicate the direction of movement, but they don’t provide any delay for the items. If travel time is significant, it is common to either:
• Increase the delay time of destination blocks to compensate for the travel time.
• Specify a minimum wait time in a Queue block’s Options tab to simulate travel time. • SetanexplicittraveltimeinaConveyItemorTransportblock,asshownbelow.
Discrete Event

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