Automatic Finite Scheduling (AFS) is the key to success for job shops

The acronym APS is well-known in the world of production scheduling. It stands for Advanced Planning and Scheduling.  But do you know what the acronym AFS means? It stands for Automatic Finite Scheduling. Both methods aim to calculate a production schedule for the planner and are based on data from resources, jobs, material availability, and routings. And do you know why is a scheduling system, based on the AFS method the significantly better alternative for SMB manufacturers who operate in a high-mix low-volume (HMLV) environment? Let me tell you that there are several reasons for this. 

The difference between APS and AFS

Both APS and AFS have the term "Scheduling" in their names. Hence it makes sense to define what “scheduling” is all about, in a first step.

The meaning of the term "scheduling" becomes easily clear when you confront it with the meaning of the term "planning". 

• In the scheduling process, the planning output is used as input data
• Scheduling defines the exact "when" and "by which finite resource" an operation should be processed 
• Scheduling boils down the rough - time bucket-related - plan into a concrete production order and resource sequence over the time scale
• Scheduling considers much more concrete restrictions than planning (e.g., finite capacity and material availability)
• Scheduling is focused much more on the short term

Now that you know the difference between "scheduling" and "planning," the next step is to describe what makes the APS different from the AFS.

Let's start with APS:

• APS schedules against finite capacities.
• APS provides automatic calculations considering multiple targets or multiple targets with a different user-configurable weighting of targets. Targets can be:
  - Job Priorities
  - On-time delivery
  - Materials availability
  - Capacity Utilization
  - Minimization of set-up costs
  - others ...
• A scheduling run considering all constraints and weighted targets needs a significant amount of time.

Let's turn to AFS:

• AFS schedules against finite capacities.
• AFS provides automatic calculations considering ONE particular target. This is usually OTD considering job priorities and material availability.
• A configuration of the weighting of targets is NOT part of the functionality. A scheduling run considering the less complex determinants needs comparably much less amount of time.

When to use which strategy?

Taking these differences as a basis, there are two determinants that ultimately decide whether the use of APS or AFS is more effective for the respective use case:

• Stability of processes

- A complex algorithm only makes sense if I have reasonably stable processes and the quality of my input data is good or can be reliably estimated. Accordingly, an APS is expedient(er)

- If this is not the case, then the long calculations and the more complex approach do not add any value. Accordingly, a quick calculation via AFS is expedient(er)

• Importance of cost-related constraints against OTD for the financial success of the business

- If there are additional cost-driving constraints that are more decisive for financial success (e.g. consideration of criteria for minimizing the set-up costs in one or multiple stages) than an early delivery date, hence when it is preferable to deliver jobs at a later date but produce it more cost-effectively, then the corresponding APS functionality provides added value.

- If this is not the case, AFS is dominant because it's faster and easier to handle.

If this is brought into a simple graph, then the recommended areas for implementing one of the two software solutions are as follows:

To sum it up

1. Both software solutions offer automatic scheduling and are therefore in the same operational area.
   
   
2. Which one of the two tools is preferable depends crucially on the respective use case: if the shop floor processes are stable and there are cost-driving constraints that have a decisive impact on the company's success, then the use of APS is a good choice. If such conditions do not exist and if the processes are not as stable but are subject to high dynamics and a very high level of customization, then an AFS is clearly preferable.
   
   

HMLV manufacturers choose AFS

Finally, it now makes sense to highlight the crucial particularities of HMLV manufacturers. Commonly these are:

• very high volatility of data due to low stability and continuity of shop floor processes
• a great challenge in quantifying exact cycle times for operations in advance due to the high level of customization
• on-time delivery and providing reliable delivery commitments are the core targets
• crucial cost-driving constraints rarely exist

Characterization of job shops - check out here: What is flow shop scheduling vs job shop scheduling?

Bringing together all these findings, it can be deduced that the use of an AFS is clearly preferable for HMLV manufacturers.

In addition, there is another decisive advantage that has so far been left out of the previous analysis: the costs of introducing and running the corresponding product. Due to the lower complexity, an AFS is both easier and therefore cheaper to implement and to use on an ongoing basis.