Infinite scheduling is the process used to schedule shop orders for sites that do not use Constraint Based Scheduling (CBS). If you choose forward scheduling, the system calculates the end date for the shop order based on the start date that you specified. With backward scheduling, the system calculates the start date based on the specified end date.
The system can handle multiple shop orders, but it always treats each shop order as if it is the only one in the system, with few constraints on resources or capacity. The system calculates the schedule for shop order operations using the least loaded resource for the work center used by each operation.
Shop order infinite scheduling considers only the following constraints:
All rescheduling of individual shop orders is performed immediately. The only time shop order operation scheduling is done in the background is when:
When scheduling the following rules are used:
Work Center Utilization: The utilization is the percentage of effective work hours per day (out of the total work hours for the day in the work center calendar). The default value is 100.
For example, if utilization is defined as 50 for a work center which uses an eight hour day calendar (8:00
A.M. to 4:00 P.M.), the effective work hours will be from 8:00 A.M. to 12:00 noon. The shop order scheduler will schedule a two-hour operation from 8:00
A.M. to 10:00 A.M. if the scheduling direction is forward and from 10:00 A.M. to 12:00 noon if the scheduling direction is backward.
The utilization percentage has no effect on scheduling if operations are scheduled by CBS or the Advanced Planning Board.
Operation Efficiency: The operation efficiency affects only the run time, not the setup time. When operation efficiency is set to less than 100% (default value) the remaining run time for machine and labor will be increased. This will result in an increased value for remaining manufacturing hours which could affect the scheduled start and/or stop date of the operation. When changing the operation efficiency, the change will also affect the standard cost of the operation. Changing the operation efficiency can be done on specific operations, if there is running-in periods for a while, which temporarily will affect the performance of the operation.
Work Center Resource Efficiency:
The resource efficiency affects both run time and setup time. If the resource efficiency is less than 100% (default value), the operation will be scheduled during a longer time period, because the setup and run time will increase. Only scheduling is affected (start and finish date on the operation), not remaining manufacturing hours. Changing resource efficiency can be done if there are different machines (resources) operating in the same work center with different capabilities.
The Advanced Planning Board (APB) allows you to perform finite scheduling (constraint based scheduling) of shop order operations on sites that do not use the Scheduling Server or have the Scheduling Server disabled. For more information, see the topic description on Constraint Based Scheduling Using the Advanced Planning Board.
Constraint based scheduling (CBS) via the Scheduling Server is far more powerful and considers many additional constraints, including constraints on resources, capacity, and tools. Furthermore, changes made on a site that uses the Scheduling Server are updated online and therefore the Scheduling Server and the schedule are always up to date, unlike with infinite scheduling or the APB. For more information about CBS, see the topic descriptions on Constraint Based Scheduling Using the Scheduling Server and Constraint Based Scheduling Using the Advanced Planning Board.