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Oracle Manufacturing Scheduling User's Guide
Release 12.1
Part Number E15190-03
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Rescheduling Discrete Jobs

This chapter covers the following topics:

Overview of Rescheduling Discrete Jobs

When rescheduling jobs you can perform the following tasks:

Some updates and changes made to jobs automatically launch the reschedule process. This includes changes to:

All other changes such as updates to the job heading, routing, bill of material, require that you manually launch the reschedule process. Refresh the Gantt chart to view these changes.

Note: When Scheduling All or Pending jobs, the scheduling engine does not schedule jobs with past due dates, or jobs outside of the scheduling horizon.

Rescheduling All Jobs

You can access the concurrent program to reschedule all jobs on the shop floor in two ways. You can navigate to the Schedule Discrete Jobs window, or access the Scheduling Parameters window directly from the Workbench. When accessed from the workbench, the workbench passes organization and discrete job information, and you only need to provide two other fields.

To reschedule all jobs:

  1. Navigate to the Schedule Discrete Jobs window.

    The Parameters window appears.

  2. Select an organization.

  3. In the Work Orders field select All Jobs.

    The scheduling engine selects jobs with a status of Released, Unreleased, On Hold that are within the scheduling horizon.

  4. In the Scheduling Mode field, select either Forwards from start date or Backwards from completion date.

  5. In the Use Alternate Resources field select either Yes or No. The default is Yes.

  6. In the Work Order Type field, select either Discrete job or Maintenance job.

    This field defaults to the type of the organization specified in the Organization field.

  7. Choose OK. The Schedule Discrete Jobs window appears.

    See: Submitting a Request, Oracle Applications User's Guide.

  8. Choose Submit.

    A Decision window appears which indicates the request identification number. You can record this number for future reference.

To reschedule all jobs directly from the workbench:

  1. Select Schedule Multiple Work Orders from the Schedule menu.

    The Scheduling Parameters window displays.

  2. Select scheduling method in the Scheduling Direction field.

    Your choices are Forward from start date, or Backwards from completion date.

  3. In the Use Alternate Resources field, select Yes if you want to consider alternates in the scheduling run, or No if you want current required resources to be used regardless of constraint.

  4. Choose Submit to start the concurrent program.

    A Request identifications number displays at the bottom of the Scheduler Workbench. When the program is complete, a confirmation window displays.

Scheduling Horizon

When scheduling all jobs, the scheduling engine does not schedule jobs with past due dates, or jobs outside of the scheduling horizon.

In automatic mode, if you grab and drag to the right (forward) or left (backward). beyond the end of the horizon, you will not be able to schedule the job. An error message displays when you choose Schedule on the Automatic Reschedule window, stating that you must either change the schedule date or cancel the transaction.

See Also

Defining Work in Process Parameters

Automatically Rescheduling Jobs and Operations

Backward and Forward Scheduling

Manufacturing Scheduling supports multiple scheduling methods including backward and forward scheduling at the job level, and midpoint forward scheduling at the operation level.

The Scheduling tab of the Resources window is where you define resource scheduling. The values are Yes, Prior, or Next. If you select Prior, you are including this resource when scheduling the previous operation. If you select Next, you are including this resource when scheduling the next operation. Finite scheduling also considers prior and next operation resources, for example, with fixed setups and teardowns. See: Defining WIP Resource Definition.

Backward and forward scheduling parameters differ depending on whether you are:

Scheduling Dates on the Discrete Jobs Window

The Discrete Jobs window has two areas holding scheduling date information: the Dates region on the main region of the window, and the date fields on the Scheduling tab. These date fields are employed in different ways.

Dates Region

When you initially create a job, you select production dates in the Dates region.

You can forward schedule by specifying a Start date. The constraint-based scheduling engine begins when the record is saved and moves the job forward to the first available time slot as resources and material are available.

You can backward schedule by specifying a Completion date. The constraint-based scheduling engine begins when the record is saved and schedules the job to complete as close as possible to that date. It calculates a production start date, according to resource and material availability.

The values in the Date region may change when the record is saved and scheduling dates are calculated. When the record is saved, these date values and other parameters (such as whether the job has an assembly routing or not, and is standard or non-standard) are used for the date calculation. See: Defining Discrete Jobs Manually, Oracle Work in Process User's Guide. If you are using manufacturing scheduling, the resource and material constraints are used in the date calculations.

Scheduling Tab Date fields

The dates on the Scheduling tab are the desired, or target, dates you want for scheduling. When you first create a job, the requested date defaults to date entered in the Date Region. After you select a Requested Start Date or Requested Due Date, the scheduling engine uses that date and scheduling constraints, and attempts to meet the request.

The constraint-based scheduling engine uses the Requested Start Date value to schedule the job from that starting point for forward scheduling, or the Requested Due Date value to schedule the job from that ending point for backward scheduling.

The dates in the Date region may change when the record is saved and scheduling dates are calculated. But the requested dates only change when you manually enter new values.

Rescheduling the Entire Shop Floor

When you reschedule all jobs on the shop floor from the Scheduler Workbench, the constraint-based scheduling engine considers:

See Also

Scheduling Dates on the Discrete Jobs Window

Defining WIP Scheduling Priority

Scheduling Objectives

You can select the primary goal of scheduling. The choice of objective determines the scheduling algorithm used and is used to maximize ontime completion, decrease the number of changeovers, or minimize slack time between job operations. Scheduling algorithms use penalty factors and machine and resource setup models. The scheduling objective is defined in the WIP Parameters window. See: Defining Work in Process Parameters, and Setting Up Scheduling Objectives.

Note: When jobs on the shop floor have varying scheduling priorities, scheduling logic looks at jobs having the same priority when determining the order operations selected for scheduling. The group of jobs with the highest priority is scheduled first, then the next highest priority group is scheduled next, until all jobs are scheduled.

Rescheduling a Single Job or Operation

Rescheduling a single job or operation on the Gantt chart using constraint-based scheduling uses the same scheduling logic as finite scheduling. The scheduling attempts to meet the due date of the job or operation, setups are sequenced, and slack is minimized. The difference in rescheduling a single job or operation is that no other jobs or operations are moved, this can effect your objectives. Start or end dates can be rescheduled both manually and automatically. You can:

Automatically Rescheduling Jobs and Operations

The Automatic Reschedule window enables you to specify the start and end dates, forward or backward schedule a job, and schedule an operation using the midpoint or midpoint forward scheduling method. The required resource and material are used as the determining factor.

Select Automatic Scheduling from the menu or toolbar, and use the pointer to automatically forward or backward reschedule a job.You can forward schedule by selecting the right of the job or operation bar. Or backward schedule by selecting the left of the job or operation bar.

The constraint-based scheduling engine uses the selected date or searches for the first available time slot as resources and material are available. The job's operations and resources move with the job.

See: Automatically Rescheduling Jobs and Operations

Manually Rescheduling Jobs, Operation, and Resources

You can forward or backward schedule using the pointer or the Edit Schedule window, enabling you to manually reschedule any job, operation, or resource without regard for constraints or scheduling rules.

You can forward schedule by selecting the right of the job, operation, or resource. Or backward schedule by o the left of the job, operation, or resource.

Or you can use the Edit Schedule window to enter new start or end dates for the required job or operation. The required resource and material are used as the determining factor.

See: Manually Rescheduling Start and End Dates

Alternate Resources

Alternate resource functionality only employs backward scheduling, because alternate resources do not use start dates: