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Batch and Collect Tutorial

An introduction to splitting and assembling work items

Step 1: Understanding Batching

Batching in SIMUL8 is the term given to situations where you split up a work item into more than one work item. For example, if a piece of sheet metal arrives at a factory, it is one work item, but at an Activity you may cut this up into, say, 2 separate pieces. You now have 2 work items rather than one, and it is important to represent this in your simulation.

This can be represented in the following way;

Before you run, there are 100 objects

After you run, those 100 objects have each been split into 2, giving 200 objects after the Activity.

To set this up, build the ‘Before’ model above, making sure to set a Start Up value of 100 work items in the first Queue;

Next, set the batch size of the Activity. The default setting is that one work item in = one work item out. Select the Activity, then Routing Out, and the Batching button (below).

The next dialog asks you to enter the ‘Batch size leaving this object’; this is the number of work items which will leave the Activity for every one which enters.

In this example, we want two work items to leave for every one work item which enters, so the batch size will be 2.

Step 2: Understanding collecting

To assemble several items together in an Activity in order to create one individual item as an output, use the Collect feature.

In the example below, we will set up the simulation to ‘collect’ one Car Body and four Wheels, in order to output one car.

First, build the structure above, remembering to prepopulate the 2 queues on the left with 100 work items each. The next step is to configure Activity 1 so that it knows how many work items to collect from each bin in order to output one car.

Select Activity 1, and go to ‘Routing In’ from the ribbon (collecting is to do with what you bring into an Activity).

Next, choose the ‘Collect’ discipline from the list on the left hand side of the dialog.

You can now tell your simulation how many work items to collect from each location in order to output one work item. Configure this so that you require 1 Car Body and 4 Wheels.

Before you run the simulation

How many ‘cars’ should you be able to create? Run your simulation and check whether this matches with your estimate.

Your simulation should look like the below; we have created 25 cars, but one is still in progress (but stuck in Activity 1 because we have run out of wheels).

To avoid moving work items if all required parts are not present, use the ‘Do not collect until all available’ option on the Routing In dialog.

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