The scheduling direction is fundamental to the scheduling process. Production can be scheduled forward or backward from any date, depending on timing and scheduling needs.

• Forward from scheduling date– Scheduling the production as early as possible. This is also known as the push method, as the production is hurried or pushed through. It can be started today, tomorrow, or from any given date in the future. The production is scheduled to start at the earliest date possible and is planned forward in time to the earliest possible end date.

• Backward from scheduling date– Scheduling the production to begin as late as possible. This also is known as the pull method, as the production is driven by the due date and pulled through the production process to its end date. It is based on the date that the production must be completed and counts backward to the latest possible date that the production can be started without missing its target deadline.

Scheduling is dependent on the availability of the work centers required to complete production. If there is not enough capacity, production can be delayed or even stopped.

Optimizing can be based on the way that capacity on the work center is calculated. If Finite capacity(or limited capacity) is applied to the operation scheduling, production is scheduled around existing reservations made on the work centers. As soon as capacity is available, production begins. The production is scheduled in the most efficient way, based on the availability of the work centers.

Operations scheduling takes each operation in the production route in the order that it is specified by date. Since the time it takes to actually run the operation also is recorded on the production route, and, if a work center group is specified for an Operation, the operation scheduling run will reserve capacity on the group. The capacity of the work center group is the sum of available capacity on all the work centers. The work center group capacity is used in connection with Finite capacity.

Scheduling also is dependent on the availability of the materials required for production. Insufficient parts or components also result in production delays. Optimizing also can be based on the use of materials. Indicating that materials available for production are critical, as opposed to non-critical, is called optimizing on materials. By selecting limited materials, the production is scheduled in the most efficient way, based on whether or not materials are available.

Note
When optimizing on both capacity and materials, production is calculated to meet both restrictions. The availability of capacity and materials is calculated until both are available at the same time in the quantities needed.

References or subproductions can be scheduled into the overall plan. You also can select to have references synchronized with the production. If this option is selected, the dates of the subproductions are moved around when changes are made to the production schedule.

If a production has one or more subproductions, you might want to schedule these together with the main production, since the main production cannot be started until the related subproductions have finished.

• Identify alternative work center– You can identify and define a number of alternate work centers at the same time that you set up your work centers. If alternative work centers are available when you schedule your production, they are used when capacity is limited and the primary work center is not available. In addition, the effectiveness of each work center can be accounted for as a percentage of full capacity, which is 100 percent.

• Efficiency percentage applicable to work center–You also use efficiency percentages that are set up when you create work centers. Efficiency percentages reduce or increase the time that is reserved for the work center, and the lead time also is increased or decreased.