In many processes, work items will be "assembled" (or 'collected') at some point. This could be as simple as putting a component inside a box on a production line. In the simulation model, the box is one type of work item, and the component is another type. In simulation terms, we are converting the 2 work items into 1.

This short exercise demonstrates how to assemble items. First, change your simulation to look like the example above by linking a Queue to Activity 1.

Select your new Queue, and use the 'Start Up' button on the Queue's 'Advanced' tab to set a Start Up condition. This places a set number of parts in the Queue at the start time of the simulation. Add 100 items to this Queue for the Start Up value.

Click on Activity 1 and select the Routing In option from the toolbar. Select the 'Collect' option. This assembles parts; so 2 parts will enter the Activity but only 1 will leave. Work will not start until all the parts required are present.

What happens to your simulation when the Stocks Queue is empty?