How do I do Job Shop Scheduling?

A job shop produces a sequence of jobs with varying quantities for a specific time period, e.g., a day or week.

Suggested Technique

Job Shop Scheduling

1. Create an arrival to a common starting activity, such as Start Job, that is connected from any entity.

2. Select Scheduled as the arrival Type and then click on the Define Schedule button to define the sequence of the jobs.

3. Create each job with an appropriate start time to cause them to be arranged in the right sequence. Don’t worry about the actual start time since this is determined by equipment availability.

4. In each arrival’s Action logic window (in the schedule dialog), name the entity appropriately using the NewName statement (see example below).

Example: A job shop can produce four different kinds of brackets. It receives an order for 100 PartA brackets, 175 PartB brackets, 430 PartC brackets, and 280 PartD brackets. The shop will produce the brackets in that order.

TO DO: Define the arrivals for each job as shown in the dialog above. In each arrival’s Action logic window, enter NewName(n) where n is the name of the entity (PartA, PartB, PartC, PartD).

Rather than using a generic named entity and renaming the entity in the Action Logic of each entry in the Scheduled Arrivals dialog, you could create each entity graphically and connect them to the same activity or storage using a Scheduled arrival connection for each entity type. Alternatively, you can use a Periodic arrival and specify zero (0) in the Repeat every field. Also note that if you don’t want the time spent waiting to start processing to be reflected in the entity cycle time statistics, enter CycleStart = Clock() in the Action logic of the first activity.

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