APS (advanced planning and scheduling) is software for production planning, the main feature of which is the ability to build a schedule of equipment throughout the enterprise.
Structurally, the simultaneous planning method can be divided into two parts:
- Production and supply planning
- Production dispatching
The algorithm of the first part is similar to the algorithm of MRP II, but it has important features: the planning takes into account such constraints as the available capacity in the enterprise (equipment, personnel, etc.) and available production resources (raw materials, components, areas, etc.). These restrictions are taken into account directly in the formation of the production plan. This approach allows to immediately get a realistic plan, while in MRP II systems, planning processes for obtaining a feasible plan are carried out iteratively. As a consequence of this (as well as through the use of other mathematical models), plans calculation using APS is made by 1–2 orders of magnitude faster and takes several minutes, as opposed to several hours offered by standard MRP II systems. That is why the method implemented by APS is often called "simultaneous planning".
The second part of the APS method, production dispatching, is performed taking into account all the limitations and critical points. At the same time, in most APS systems, it is possible to impose additional restrictions on the process of operational production management. For example, you can require the combination of production batches to form a batch that is optimal for launch.
In addition to the simultaneous planning, APS systems are able to realize the following features:
- Optimization planning. Optimization in APS systems is carried out by using heuristics and/or complex mathematical models that are created for a specific industry or a particular enterprise.
- Rapid response to changes in the production environment (delay in delivery, equipment failure, etc.). The APS system allows to quickly obtain a new plan, adjusted to reflect the changes that have occurred.
- Distributed planning. Several people can participate in the development of a plan at the same time, but each of them is responsible for a certain planning zone (these are either separate machines or a certain planning horizon).
- Ability to use web-based technologies that provide remote work with plans.
- Effective visualization tools and report generator.
The concept of APS is not yet standardized and is interpreted differently by various organizations and suppliers of production planning systems, from a superstructure over MRP II planning to an independent approach to production planning.
In the IT-Enterprise system, the APS-plan is formed taking into account the limitations imposed by the permissible capacity utilization, the actual and forecast availability of materials and other production resources. As a result, detailed operational production plans are obtained for each work center with an optimal order of work.