Supersession and Product Interchangeability

Supersession is actually a subset of of the broader functionality of product interchangeability, which you can read more about here.

http://www.scmfocus.com/sapplanning/2009/04/21/product-interchangeability-and-scm/

There are two different possible directions of interchangeability for supersession:

1. Forward interchangeability
2. Fully interchangeability

SPP uses two scenarios (supersession and form fit function classes) for location product interchangeability.

• Supersession is where items are replaced or substituted for one another.
• Form fit function classes are where several products can be substituted for one another if they have the same form fit and function.

The supersession in SPP is the same as that in the best of breed solutions that proceeded SPP. One way, two way, many to one, one to many. These are setup with boolean logic of “AND”, “OR”, etc..

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Business Corner

It can’t be emphasized enough how important the master data is for all forms of supersession. If the implementation of SPP is the first time the client has implemented a service parts planning solution, it is unlikely that the supersession database (the database of linkages) is good enough to run the planning engine. Its important that this issue be brought up as early as possible on the project. I have seem a client put emphasis on whether SPP would be ready from a functionality perspective with regards to supersession, without checking their supersession master data to see if it could support the SPP supersession functionality.
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Replacement Strategy

In SPP you can model supersession to create various replacement strategies. A replacement strategy is made up of a replacement type. In SPP it is possible to only partially replace a product, to replace several predecessor products with one sucessor product, or to replace a predecessor product with several alternative successor products. There are several replacement types that are available:

1. S_0L1L: 0:1 – Location substitution. Use this replacement type if a validity date is to be maintained for the predecessor location a location substitute chain.
2. S_0LP1LP: 0:1 – Location Product substitution. Use this replacement type if a validity date for the predecessor location product is to be maintained in the location product substitution chain.

There are of course many others – they are listed on page 361 of the SAP training material. However things like the following are covered:

• Assembly
• Group
• Location
• Location Product
• Location List

This configuration setup is described in this post under Maintain Replacement Types.

http://www.scmfocus.com/sapplanning/2010/09/05/spp-img-setup-supersession/

In order to plan with interchangeability in SNP and PPDS you need to create an interchangeability group of the group type supersession chain and assign it to one or more locations. You can create more than one supersession chain. No product may be included in more than one supersession chain at a time. Configurable products can not be used in substitution.

For each supersession chain a planning package is generated automatically for the location products and linked to their master records. This planning package contains the PPDS heuristic SAP_PP_I001 with which the products of the supersession chain are planned in the correct sequence.

During supersession planning the system plans according to the following process.

1. If you have not specified the group type orapplication relevance correctly, the system creates a message in the application log.
2. The system checks the start date of the discontinuation period and only calculates more date values if this date has already been reached. If the date still lies in thefuture, the system does not calculate the stock exhaustion date and planning date. If the datehas been reached, the system continues with the next step
3. The system calculates the stock exhaustion date. This date depends upon the entry location and specifics when the available stock of the predecessor product is likely used up.
4. The system carries out step 3 and 4 until it reaches the product planningdate of the successor product
5. On reaching the planning date, the system realigns thepredecessor product demand history for the successor product and begins forecasting, inventory planning, andDRP for the successor product.
6. The system checks daily whether the stock exhaustion date comes before the stock exhaustion warning date and therefore the stock of the predecessor product.

The replacement type is chosen on the interchangeability master.

The general settings for supersession contain parameters for the calcuation of the successor product planning date and stock exhaustion warning date.

Logic:

1. Wait till pending obsolescence date
2. Determine stock exhaustion date
3. Calculate backwards to determine successor product planning date. Considering lead times for the successor product from suppliers within network and safety.
4. Repeat step 3 until the successor product plan date is reached
5. Realign demand history and start forecast, inventory positioning, inventory planning and DRP for successor product

In SPP you can model supersession to create various replacement strategies. A replacement strategy is made up of a replacement type (for example one to many substitutions or many to one substututions.

1. Several products together replace one product (AND)
2. One product replaces several products (AND)
3. Several products replace one product (OR)
4. One product replaces several products (OR)

There are a number of replacement types defined in the standard system.

1. S_0L1L: 0:1
2. S_0LP1LP:0:1
3. ect… (one page 361 of 2nd SPP manual)

The general settings for supersession contains parameters for the calculation of the successor product planning date and the stock exhaustion date. The advantage of working with this type of product interchangeability is that you will be more likely to cover requirements that occur at one location without having to make any more new procurements. Even if a particular product is not available, you may be able to cover demand for this product by using another product with the same form fit function class.

The detail of the replacement types is maintained in SPRO.

After these are created we can assign to an interchangeability group.

Now we can see that the replacement type S_1P1P is assigned to the replacement strategy fro 1:1 supersession.

Now we will see the time buffer and the safety stock percentage.

Now we want to create the interchangeability master record needed for 1.1 product substitution. /INCMD/UI

There is actually a lot going on in this configuration screen. We get into more detail on it here.

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The configuration starts off by requesting the Group Type. The following options are given.

This screen is used for things other than supersession, which are basically different types of substitution. However, since we are focused on supersession for this post, we would select Supersession Chain.

You also need to select what the supersession chain is to be used for. (for Planning, for Planning and ATP or just ATP). I have to say, using the supersession chain for just ATP would not make a lot of sense to me.

Now we need to select the options that come up below for the Supersession Chain.

To learn a bit more about the Interchangeability Group, see this post.

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Now we will enter our product location data.

We also want to set the date as today and the validity date from today and direction as forward.

Next we want to click the release button (the green flag)

Now we will go an assign our supersession chain to the active model. /N/SAPAPO/INCMD_MODEL

Now we will create a supersession profile.

Now we need to define the planning profile.

Next we goto the DRP Matrix to look for substitution orders.

Conclusion

Supersession is a critical capability for service parts planning. SPP has the functionality to perform a number of complex supersession scenarios, and configuring this functionality, as well as maintaining it is a lot of work. SAP has created a number of screens and options, however I would have preferred a simply upload of a CVS file that had plain text headings for what the different supersession types should be. I am skeptical of company’s ability to maintain the configuration settings for supersession, and can see the functionality end up getting left out, and the supersession being done manually.