Production planning and control (PPS)

The aim of production control is to implement the production planning specifications in production in the best possible way and to integrate production plans into the daily production process. In order to continue the planning content, it is the task of production control to transfer this to specific work instructions and to ensure that orders are completed on time and in the required quality. This corresponds to task fulfillment and includes all measures that are necessary for production execution in order to control the material flow so that the orders pass through production without delay. Here, the availability of capacities is checked, production orders are released, production progress is monitored and, if necessary, adjustment measures are carried out in the event of deviations between target and actual values. In addition to order initiation, order monitoring plays a significant role in ensuring that targets are met.

Order initiation

The starting point for order initiation is the results of capacity scheduling, which are presented in the form of rough-cut planning for the production orders. The task of order initiation is to release the specific production orders for a certain planning period. As part of detailed planning, an availability check of required resources, a machine allocation plan and sequence planning for optimal order processing are also carried out. One challenge of order release is the objective of minimizing throughput time while maximizing capacity utilization. This means releasing production orders in such a way that capacity utilization is as high as possible and throughput time is as short as possible.

Availability check

Part of the availability check is checking the availability of materials, tools and employees to complete the scheduled orders. The production control tasks begin with the availability check for individual workshop orders. In this context, once the workshop orders have been scheduled and released, their feasibility in terms of materials and capacity is checked. The release note for detailed scheduling is only to be issued if the start date is ensured by the provision of materials based on throughput scheduling and capacity planning. If the materials are not available, the detailed scheduling or even the production program must be adjusted.

Sequence planning

Sequence planning defines a specific processing sequence for the production orders in which the operations are processed on the operating resources. Within a planning period, different production orders are available for processing at a capacity and thus generate a queue within the processing. In compliance with the required end dates, sequence planning aims to achieve an optimum processing sequence with the help of selected criteria. Possible criteria can be fixed selection criteria, such as priority rules, or cumulation criteria in the form of minimizing setup times. The production orders in the queue are re-sorted according to their scheduling urgency, identified by a priority number and thus assigned a new position in the processing sequence.

Order changes can be made until immediately before the order is released. Following on from the sequence planning, the work content is divided up and allocated to individual workstations. The result of sequence planning is a work distribution list, which is displayed in the form of a system-related schedule. As a result, production orders are assigned to individual machines or individual work steps in the machine allocation plan. After detailed scheduling and detailed resource planning, the order is released according to different procedures or rules. The release initiates the provision of resources with all associated material, wage and confirmation slips and activates the order in production. As soon as an order has been released, the orders are carried out in the specified sequence.

Order monitoring

The core task of order monitoring is to provide feedback information on order completion during production in order to compare the actual data with the target specifications and take corrective action if necessary. Order progress monitoring is usually decentralized in the individual production areas due to the high level of detail in the finely scheduled plans. Machine and employee-related data is collected for capacity monitoring. The basis for all order progress monitoring is production data acquisition (PDA) for monitoring both orders and capacities. The machine-processable operating data focuses on collecting and displaying order, machine, employee and material-related data. Order monitoring requires data on the start and end date of the operation, the time of interruption, the order quantity, the number of good and reject parts and the resumption of interrupted operations.

The results of order monitoring are forwarded to all adjacent PPS areas and are of an informal nature. In addition to order monitoring, it is also necessary to monitor the scheduled resources and constantly check their load situation. As soon as an under- or overload of the capacity limits is detected, changes are made to the detailed scheduling or sequence planning. On the material side, the reasons for delays must be checked. If disruptions occur, these must be adjusted to the original order specifications with the smallest deviation. In most cases, they are realized by building up inventory flexibility in the form of process, product and potential reserves. However, preventive measures should be taken to ensure production continuity and to achieve the PPS targets.