This process is used to allocate production resources to fulfill planned orders and other non-productive activities necessary to ensure the continued availability of these resources.
After using this process a schedule covering the placement, timing, quantities, and priorities for assigning the necessary resources to fulfill planned manufacturing orders is set. Preventive maintenance and other necessary activities are also scheduled.
The process can be started when these prerequisites are met:
Order and work center scheduling includes all the activities required for detail scheduling manufacturing orders.
Detail production planning covers the following activities:
Order and work center scheduling involves planning in detail the sequence of when operations are carried out in work centers. This scheduling is important for several reasons, the most important being:
Order scheduling involves setting the order start and finish times, priorities and the sequence orders are to be produced. Work center scheduling involves setting start and finish dates for each operation for when the order is actually produced in each work center to minimize queues, setup times, lead time or maximize utilization of tools. Order scheduling can be done per shift or weekly, and work center scheduling is done whenever production on an order is to be started.
The list shows the most commonly used methods for order and work center scheduling.
Backward scheduling involves scheduling operations backward through the routing starting at the order finish date, taking into account the lead time (operation, queue, transit and setup times). Forward scheduling begins with the order start date, setting the first operation in the routing and scheduling forward in time to the last operation. The operation start and finish dates are used to sequence orders in order of priority and judge the order’s progress.
M3 uses either backward or forward scheduling whenever the planned order is released, that is when the manufacturing order is created. This can be done either considering or not considering finite loading.
Gantt charts help with graphical displays for scheduling and monitoring job scheduling across operations, evaluating load and capacity, and project scheduling. Gantt charts can be used in M3 in Work Center Scheduling Manufacturing Order. M3 can also be used with integrated external systems (with detail planning) for interactive scheduling using Gantt charts.
Simulation is the process where a model of the real system is used to evaluate various outcomes from possible solutions and decisions. This can be done by creating different versions of the requirement calculations or using an external scheduling system.
Finite loading is when the loading for all work centers is kept at or below 100%. When the orders are scheduled work center by work center, this is called vertical loading. Horizontal loading is another approach where all operations are scheduled, order by order, for all work centers.
Regardless of the method, set priority rules are used to determine the sequence orders are scheduled and weight factors are used for such considerations as the job’s urgency or importance.
Both vertical and horizontal loading can be used in M3 for forward or backward scheduling. This is done either when the order is released or in external scheduling systems integrated with M3. Vertical loading can also be carried out as forward scheduling in Work Center Scheduling Manufacturing Order.
A priority rule is a set of steps for assigning priorities to orders waiting to be processed in a work center. Using a priority rule ranks orders in a recommended sequence for production. M3 includes several different priority rules which can be used in Work Center Scheduling Manufacturing Order.
The work center schedule can be printed using (‘Work Center Schedule. Print I’ (PMS610) or (‘Work Center Schedule. Print II’ (PMS625). For the latter, the layout and specific information printed is user-defined. This is the same view as used in the work center schedule. See
MO documents can be printed when the order is released and transferred to the production database. Any selection of orders can be printed in (‘Manufact Order. Print Documents’ (PMS240). Documents for separate orders or per operation are printed in (‘Manufact Order. Print Separate Documents’ (PMS250). Documents can also be printed from other programs, such as (‘Work Center Schedule. Open’ (PMS230)). See Work Center Scheduling Manufacturing Order.
Salvage, rework or scrap can be done whenever the specifications of the scheduled order cannot be met (either in whole or in part). Scrap occurs when the product is no longer usable by the manufacturing system. Rework is when one or more operations are added to the order to bring it into compliance with the original specifications. Salvage is when the order is stopped so the material or components can still be used, but for another purpose.
An order for rework or salvage is scheduled like any order, but is completed only when capacity is available or a need for the salvage components arises. Also, an order can be split so the problem-free portion can be completed.
There are two kinds of maintenance: preventive and breakdown. Both types of maintenance belong under the control of the PAC system since they require the detailed allocation of personnel, material, tooling and machinery as with ordinary production.
Preventive maintenance can be separated into so-called in-process maintenance, carried out during production, and out-of-process, when the resource is unavailable for production. The latter is normally done using a work order similar to a regular order, which is included in detail scheduling. These are planned in advance to limit the risk for unscheduled downtime, and minimize the disruptive impact on capacity, allowing the reallocation of freed resources for normal orders.
In M3, maintenance is planned and carried out within the framework of the maintenance system. As of R10 this system is not integrated with PAC. A regular manufacturing order a must therefore be created to include a maintenance work order in detail scheduling.
Production resources can be allocated to other activities such as scheduled downtime or indirect labor. These activities are carried out to level current capacity utilization or reallocate available resources for other tasks such as indirect labor. This is done by reducing the capacity of the resource accordingly.