Planning Vs Programming: what is the role of the APS?

Do you know the role of APS? There are basically two major processes covered by APS, Planning and Scheduling. And with many advantages, due to the fact that it allows production plans to be made from short to long term, covering the entire production chain and taking into account practically all the variables and constraints of the production environment.Some terms may be related to the same subject, such as Fine Production Planning Software or Finite Scheduling Systems, as well as "Advanced Planning Systems" in English. See more about the origin of APS! If we analyze the main processes of Supply Chain Management, we will find the configuration below, in which it is possible to identify where solutions aimed at Planning and Scheduling fit in.[caption id="attachment_2686" align="aligncenter" width="1024"]

Supply Chain Management and APS[/caption]

Production Planning with APS

Many may think that an APS solution focuses exclusively on Detailed Production Scheduling processes (the first versions did not include Planning, or at least not with finite capacity, so the perception of the APS concept was only linked to the Fine Scheduling process), but a complete APS covers much more than this. The Production Planning process basically aims to define what to produce in each planning period and in what quantity, which is represented by the Master Production Plan. It is based on actual and/or forecast demand for each period of a horizon, which can vary from weeks to months, and the stock and fulfillment policies that each product has (these policies end up being used mainly by companies that produce for stock, but companies that produce on demand also need to do their Planning).This process is usually carried out using the ERP software itself, which, as we have already seen, has its limitations in terms of restricting production capacity to generate these production plans. As in Planning we work with a more macro and less detailed view of resources (it doesn't necessarily matter how that production will be carried out within each shift and each day, but rather how much will be produced that week for each product), these limitations are therefore less critical.Even so, if some business rule is required, if bottlenecks can be dynamic, or if the variety of SKU volumes is very high, other restrictions not easily managed by ERPs can arise. It is worth remembering that the Planning process (usually attributed to Master Scheduling), by definition, is subsequent to S&OP, Sales & Operations Planning. Even so, it can be closely related to APS for two reasons: firstly, because of S&OP's characteristic of using a long horizon, which generates a greater need to simulate scenarios in the face of future uncertainties; just like Resource Planning, which interacts with S&OP and needs to see productive capacity.As APS has all its dynamics based on this scenario generation and capacity management, it can greatly support collaborative sales and operations planning.The difference in how APS will act in each of these two processes basically consists of the level of granularity of each one, both in terms of its position in the Supply Chain process cycle and its objective.FeaturesAPS (Planning) -> S&OP

APS (Planning) -> MPS

Horizon

Horizon of 3, 12 or more months

Horizon 1 to 3-4 months

ObjectProduct families

SKU

Constraints ManagementOnly the most critical one(s)

More restrictions

While S&OP will look at a longer horizon to support the tactical and strategic level, probably by analyzing product families, MPS will work with a horizon linked to the maximum accumulated supply lead time (i.e. the longest path in time between the purchase, production and delivery of a product).If we were talking about Production Planning to support an S&OP process, we could afford to look at only the most critical constraints and work with sales forecasts by family, which would then be broken down into SKUs (Stock Keeping Unit, or simply a product). If we're looking to support the MPS (Master Schedule) itself, we'll look at the finished level per SKU, which generates the formal MPS, and then we'll explode this demand into the other levels of the product structures to define what should be produced and purchased, assessing the capacity impacts we may have in each planning period and taking action to adjust capacity and demand in that period. In this process, simplifications that were made in S&OP can come to light here, highlighting restrictions and idleness that may have gone unnoticed and which will have significant impacts on the operation.The explosion of material requirements, characterized by MRP/MRPII in the traditional bibliography, could be here only at the planning level. However, we understand that, due to the dynamism of materials management today, we can no longer think of MRP, even with finite capacity, without considering that it must support a short/medium-term process, recalculating needs based on the plan revisions that Fine Programming carries out. It is therefore included in both solutions.

Production Scheduling with APS

The Production Detailed Scheduling process starts from the volumes to be produced previously defined in the MPS, or simply from continuous customer order demands for the MTO (make-to-order) industry, with the aim of defining in detail when each demand will be produced and (this is the main critical point of this process) "how". Here, each of the operations necessary to manufacture a finished product will be sequenced, or at least the main ones, if the bottlenecks in these processes are stable and defined. Since APS increases the degree of precision of this process, we call it Fine Scheduling. First of all, it's important to know what will be programmed, what we call the Programming Object. Each company has its own way of managing it, but the most standard nomenclature is the Production Order (PO) or Manufacturing. It was created from the MPS we saw earlier, or even from MRP. However, a PO is not just a reflection of the net requirements from MPS and MRP. Production policies must be applied here, such as information on the minimum, multiple and maximum batches allowed by the industrial area for the execution of each process. In other words, the MPS can generate a production requirement of 5000 units of a product for a given period, but if the maximum batch is 2500 units, we will have two Production Orders. If the APS receives a Production Order of 5000 and we need it to split it up, it is entirely feasible to do this. However, the complexity of managing the integrity of the information between systems, needing to explain to the production control system or to the ERP itself that the order has been split and now each one can follow a different path and needs to be managed individually, makes it more efficient to carry out this split at its source, i.e. when generating the PO itself (in whichever system).Ideally, scheduling allocates demands in the form of production orders to production resources (a machine or workstation itself), according to different heuristics and simulations, depending on the objective (why heuristics and not optimization?). As a result, each resource receives its list of orders to produce, with the exact sequence to be followed. The main characteristics of the classic APS for Fine-Grained Programming are:

• Finite capacity: in this case, the real capacities of the resources are taken into account, i.e. work is allocated to the resources only up to their limit;
• Finite constraints: in order to faithfully portray production, scheduling takes into account all the operational constraints that exist in production, such as limitations on tools, operators, dies, gauges, electricity, among others;
• Sequence-dependent use of capacity: the way in which capacity will be consumed must vary according to the sequence, from the variation in Internal Setup times to the distinction in efficiency between machines capable of carrying out the same operation;
• Materials management: the interdependence between production and the availability of materials needs to be considered, looking at the stocks available for allocation to the production orders that will consume them, as well as the expected arrivals of more materials and the allocation restrictions and priorities they may have;
• Relationship between orders: production orders can be linked statically or dynamically, thus ensuring better control over production;
• Rescheduling: due to unforeseen events and changes in production, these systems allow instant rescheduling to keep the entire company up to date. This can be either a weekly review of what will be produced in agreement with the other areas of the company, through S&OE, or a one-off change due to an emergency;
• Scenario simulations: by demonstrating the reality of the company's production, it is possible to simulate performance analyses and the costs involved with the use of overtime, outsourcing, equipment purchases, batch divisions, etc;

Comparative summary of the two parts of an APS solution

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APS Planning and Scheduling[/caption]Looking at the whole picture, we understand that today we have enough technology to make a process increasingly integrated. There is no reason to carry out an MPS looking at finite capacity in terms of the finished product, considering only one chosen bottleneck, and then exploding the other needs by MRP, without looking at other restrictions. We must also understand that changes in demand and supply will occur and the need to feed the flow quickly and assertively is growing. We did this in the 80s and 90s because there weren't enough effective alternatives. Today is different. This evolution is not a quick process, but it is essential for anyone looking for agile and efficient supply chain management. So, would you like to know more about Supply Chain, APS and other content? Follow the NEO Blog Enjoy and follow us on LinkedIn and other social networks to keep up with more news.[noptin-form id=2822]