SAP APO - Planning and Scheduling using Resource Networks

Posted by Raghava Itharaj on 06-Sep-2017 20:30:30

A high-level insight on Resource Networks was provided in one of our earlier blogs entitled “Semi-Finished Goods Scheduling within SAP APO”. In this blog, I intend to provide a more detailed insight on how Resource Networks can be utilised in both SAP APO Planning and Scheduling scenarios.

A Resource Network is best described by the physical connection between Resources of different production lines. It models the flow of materials through these lines from one Resource to another. Some scenarios include:

  • Scheduling across the allowable connections between packaging lines and semi-finished goods lines
  • Recognising the prioritisation across multiple semi-finished goods lines feeding into a packaging line
  • Providing flexibility to switch between alternative input resources in the case of capacity constraints

In the ever-increasing drive towards full production efficiency, Resource Networks can be used to manage and utilize production assets to their maximum extent, ensuring the input/output of material flows between resources is optimised.

Industries where this maybe applicable include FMCG, Chemical, Pharmaceutical and Food & Beverage. Resources at different stages of production are required to interact with each other through physical connections to supply raw materials or semi-finished goods to the downstream Resources. By using SAP Resource Network functionality, businesses can achieve effective automated planning and scheduling of the right orders on the right machine at the right time. This leads to improved production efficiency and less reliance on manual scheduling updates.

Customer Use Case

As an example, Olivehorse implemented PP/DS Resource Networks for an FMCG customer (toothpaste and shampoo/lotions manufacturing facilities). In both manufacturing facilities, there were two levels of manufacturing: Finished Goods (FG) and Semi-Finished Goods (SFG). Multiple SFG mixers could feed SFG material into the FG packaging line and there were also intermediate storage tanks that held the SFG material for a defined period as an intermediate material staging.

SFG to FG.jpg

In general, the storage tank capacity was based on the batch size of the SFG material produced on the SFG mixer. Modelling the capacity of the intermediate storage tanks was done using Min/Max stock levels of tanks which was respected by the planning algorithm and could be visualised graphically (see previous blog on Scheduling SFG).

The key challenge for scheduling the mixers was that multiple SFG mixers could feed a single FG packaging line and the mixers should be selected by priority and availability.

The PP/DS scheduling solution therefore needed to take all these constraints into account.

What Benefits Were Achieved?

  • Overall Equipment Effectiveness was increased due to reduced waiting time of SFG mixers to fill the intermediate storage tanks and an increase in resource utilisation at the FG and SFG levels.
  • The solution achieved advanced automation with minimal manual intervention in re-scheduling
  • The solution generated a more reliable production plan through better anticipation of SFG demand by FG orders by handling the bottle neck resources efficiently

Overview of Resource Networks

Below is a simple schematic of a Resource Network showing the relationships between FG packaging lines and SFG mixers.

Resource Network.jpg 

The arrows indicate the flows from SFG to FG lines, with the red arrows indicating the highest priority of the Resource Network and all others represent lower priorities. Every FG packaging line is connected to one or more SFG mixer line and every FG packaging line has a preferred SFG mixer line from which to source the SFG material from.

Resource Networks provide the scheduling flexibility to utilize the priorities for sourcing SFG material from alternative mixers in case of capacity over load, down time and other scheduling constraints.

The prioritization in the Resource Network will be triggered by the requirement of SFG material by FG orders. The machine operators and planners play a key role in deciding which FG resources need to be connected to which SFG resource. So, the design will be made based on numerous factors on the shop floor such as compatibility of the resource, distance between the resource, resource grouping based on homogenous products etc.

Practical Challenges

Resource Networks can grow in complexity as the number of machines involved increases. The more complex it becomes; the more challenges and constraints will arise for the businesses to handle.

  • PDS mode priority of the SFG material will differ from the Resource Network priority (i.e. the packing line requirement will influence which SFG mixing line should be used)
  • Finite resource capacities, overload and downtimes need to be considered during SFG and FG order scheduling
  • Alternative SFG mixer priorities, intermediate storage capacities and bottle neck resources need to be considered
  • Lot sizes (fixed and lot for lot) logic needs to be determined to make the models work effectively

Planning and Scheduling Techniques

To apply Resource Network logic onto a scheduling model, there are different techniques available via PP/DS Heuristics or PP/DS Optimiser. Both methods require certain system prerequisites

  • Resource Network together with the prioritisation logic
  • Routings/Recipes in ECC with alternate sequences
  • Multiple PDS modes on the SFG mixers so they can be scheduled dynamically across alternative resources

PP/DS Heuristics

The heuristic method will first generate the SFG planned orders infinitely onto the primary PDS. This will lead to an initial scheduling solution which shows overloads on the primary SFG mixer. As a secondary step, a Rescheduling Heuristic runs which shifts the overloads whilst respecting the Resource Network logic so that the SFG orders are now positioned onto the allowable, prioritised mixers.

Planning and Scheduling Techniques

The PP/DS Optimiser can also be used for generating SFG orders as well as scheduling using Resource Network logic. The PPDS Optimiser considers different weightings such as overall make span, total setup time / cost, total delay cost to arrive at an optimised plan for both FG and SFG.

Optimisation with Resource Network Costs

As per the standard PP/DS optimiser, cost parameters will not be considered for Resource Network priorities. Olivehorse however have developed enhanced functionality by adding costs for Resource networks and running PP/DS optimiser to consider these costs during optimised scheduling. Weightings will be added to the Optimiser logic to consider priorities and costs of Resource Networks along with other standard weightings.

Conclusion

At Olivehorse, we have seen first-hand how PP/DS Resource Network functionality has provided real advantages to businesses where multi-level manufacturing is a requirement. We have gained extensive experience in handling and implementing complex planning and scheduling scenarios and would be happy to discuss any specific requirements.

Raghava Itharaj

SCM Consultant, Olivehorse Consulting

Download Optimise your Optimiser Report

Read more on: SAP APO, SCM Optimisation, PP/DS, snp, supply network planning, resource networks