Overlapping Operation Processing - Scheduler

You define overlap on an operation to represent the number of run hours the previous operation must complete before this operation can start. When you run the Scheduling activity, the Scheduler splits the job with overlapping operations into smaller loads. This allows a resource to work on one smaller load at a time and complete it faster. The Scheduler generates split load sizes in terms of a number of items or a number of loads, based whether the operation is using fixed schedule hours, as follows:

If Use Fixed Schedule is...	The Scheduler splits the loads using this calculation
Selected	# loads = Fixed Sched Hours / Offset
Cleared	load size = Offset / Run Duration

Note: While the system will let you, we don't recommend defining offset with fixed time operations. Each split load will use the entire operation time if there is a fixed time defined. This will make the operation take much longer then it should.

Each load attempts to allocate the resource or resources associated with the operation according to the resource's selection rule. After allocating a resource and completing any setup and run time, the load moves immediately to the next operation without waiting for the original job's quantity to be completed.

Uneven Split Sizes

The job quantity may not be evenly divisible by the split size. If this occurs, the Scheduler processes the uneven remainder of parts by creating a new load.

For example, assume the job quantity is 100 and the load split size is 25. The number of whole loads is determined by dividing 100 by 25, which results in four loads of 25 each. But if the load split size were 30, there would be 3 whole loads of 30 and a remainder of 10. The Scheduler places the remaining items in a load of 10.

Setup Time Consideration

The Offset value begins when run time starts. Run time starts after Setup time is complete.

For example, suppose you have a load moving through Operation 10 and Operation 20. Operation 10 has 1 hour of setup time and 1 hour of run time. Operation 20 has an offset of 0.5 hours. This offset value will cause the order to split into two loads (2 loads = 1 hour run time / 0.5 offset hours per load). Operation 10 starts by processing load 1 through 1 hour of setup and then 0.5 hours of run. At this point, load 1 proceeds immediately to Operation 20 and load 2 starts at Operation 10.

Note: If Operation 20 also had setup time defined, load 1 would start undergoing setup time only after being completed at Operation 10. You cannot start the setup time on a subsequent operation before the load is completed at the previous operation.

Multiple Resources in Resource Group

If a resource group contains multiple resources, the loads can potentially allocate all resources and begin processing at the operation concurrently. For example, if you have 2 loads moving through Operation 10, where the required resource group contains 2 resources, each load can allocate one of the two resources (according to the selection rules).

How the Scheduler Recombines the Split Loads

The Scheduler combines the original load back together:

When, after processing an operation that allows overlapping, it encounters an operation that does not allow overlapping (that is, an operation with Use Offset Hrs=No).
When it reaches the last operation in a routing.

See Overlapping Operations Example for an illustration of a possible overlap situation.