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What is an APS?

APS is one of the famous LTA (three letters acronyms) of business software and operations management and it has two different translations: Advanced Planning and Scheduling and Advanced Planning System. APS are software systems that started spreading in mid '90 and they have overtaken some of the limitations of ERP system with respect to manufacturing and operations planning. ERP systems have a transactional nature and give a minimal graphical representation to resources' load, purchase orders, stock levels, etc. Instead the production planning process needs a lot of fast computations and, at the same time, both analytical and sintetic views about the purchasing and production plan. APS systems has three distinctive features with respect to the production planning modules of ERP systems:

  • computing speed
  • better graphical representation of the plan
  • a greater modeling power (especially useful for their finite capacity scheduling engines)
  • APS systems differ one from another about several characteristics, often related to their origin: some of them are large applications developed by big players of the business software industry; others evolved from simulation packages of the '80 and have feature almost confined to those of a finite capacity scheduler (i.e. programs that create order sequences for the production resources). A complete APS must support the following processes:
  • independent demand management
  • infinite capacity planning
  • purchase planning
  • finite capacity scheduling
  • performance monitoring
  • integration with other systems
  • Now we will see what this means in further detail.

    Independent demand management

    Independent demand is made of sales forecasts and customer orders. Managing independent demand means determining resources that need to be forecasted, computing the future quantities, matching them with the sales orders to adjust the production plan.

    Infinite capacity planning

    The infinite capacity planning is the activity traditionally accomplished by the MRP and CRP procedures. They create a plan which considers the production resources (machines and personnel) is available in infinite amount. This type of elaboration, that may seem limited at first sight, has a great value for mid-term and long-term plannig because it gives evidence to mismatches between capacity and load when there is still time to forefront them.

    Purchase planning

    A purchase plan is created after the stock levels and the production plan requirements. Both production and purchase planning are constrained by the availability of technical specifications or decisions associated to the life cycle of products and components (materials that must be used up to their stockout, materials that must be dismissed for new regulatory reasons and so on). Many APS are able to manage also these issues.

    Finite capacity scheduling

    This is an activity and a computations that concerns the short-term and it consists in creating sequences of production orders for the machines and people of the productions system. We talk about finite capacity with the meaning that the (finite) number of hours of available capacity in a day or other time bucket is considered a constraint (capacity is hardly modifiable in the short run while in the long term it can be varied with the introduction of new resources).

    Performance monitoring

    The great computing power of APS systems allow us to compare different production and purchase plans. On the other hand is important to be able to verify if the production system have executed the plan or if it has changed it for some reason, even the fact that the production model is not well suited.

    Integration with other systems

    APS systems usual import and elaborate data usually created on other systems (bill of materials, stocks, etc), so it is fundamental that they can easily communicate by means of different technologies with these systems (dbms, spredsheet, file systems, web services, etc).

    If you want to introduce successfully an APS system in your company it is fundamental the expertise of your software provider and integrator. Probably the importance of this kind of factor will decrease both for the great integration flexibility and user-frienliness of the systems and the presence of power users inside companies. Another fundamental aspect related to the success of the implementation in the long term is the possibility to parameterize and customize the application easily to make it fit better to the new scenarios. Not all systems allow to do that with an acceptable cost and in a fast way.