What is Part Supersession?
Supersession is one of the most important functions in any service parts planning system. Supersession is used to both:
- Substitute one part for another part
- Obsolesce parts due to engineering changes driven by PLM (Product Lifecycle Management) that need to be replaced by newer versions
The supersession configuration in service parts planning systems allows this to be performed automatically during the planning. In MCA SPO this supersession is handled by configuring whether the part is subject to supersession and the type of supersession (One Way or Two Way that applies). We will use the description of supersession in the MCA Service Parts Optimizer Glossary of Terms:
Supersession in MCA
Used to specify that a Part should be replaced with a different Part (referred to as a Planned Part). Supersession processes are part of the forecasting batch process. They transform demand, population and inventory data to reflect it on the currently planned versions of the Part. Three types of supersession processes are performed on data within SPO: Demand Supersession, Contract Population Supersession and Inventory Supersession – MCA Glossary
Indicates the type of Supersession applicable to a Part. This value (ONE-WAY or TWO-WAY) is used to determine if inventory of the superseded Part can be used for satisfying demands for the superseding Part. Inventory of TWO-WAY superseded Parts is added to the inventory of their superseding Parts, whereas inventory of ONE-WAY superseded. – MCA Glossary
Supersession in SAP
When an external system that is specialized for service parts planning tells SAP what to do, SAP can simply execute the recommendations made by the external system. However, the question arises what SAP ECC’s capabilities are with supersession.
According to SAP web sources, supersession resides in:
- Advanced Planning and Scheduling (in SCM)
- Supply Chain Management
- Service Parts Management (within SCM)
- In ECC
Supersession in SAP SCM/APO
SAP documentation states that its SCM module has supersession capability. However, the SAP Service Parts Planning solution is so lightly installed (as of mid 2007) that it does not well represent the supersession capability on a typical SAP install, specificially SAP ECC. However, outside of SPP, APO has supersession (called substitution or interchangability outside of service parts). The way to arrive at it as of SCM 5.0 is to goto
APO – Master Data – Application-Specific master data – Product and Location Interchangeability – Maintain Interchangeability group
You can apply the substitution here or if you are using CTM, in the CTM profile. (see our sister blog for an explanation of CTM)
This is fairly simple, you can see from the screenshot that we have populated the following information:
- The Group Type (supersession chain)
- The Group name – SNAPP_GROUP
- The Group description
- What the supersession is relevant for (for both planning and ATP)
- Next set the preceding part and the succeeding part
Finally we save this and we will have just created an Interchangeable Group.
Next I need to assign a location. What this means is we can create supersession relationships that just apply for particular locations but not for others.
We have not been able to verify this, (as we presently lack access to a SCM 2007 aka SCM 5.1 system), however the functionality of supersession – interchangability has been enhanced and is now located at:
Advanced Planning and Optimization (SAP APO) – Service Parts Planning (SPP) – Master Data and General Functions for SPP – Product Interchangeability in SPP
The enhancement relates to the ability to use form fit function classes in addition to product supersession. “That is you can define a product as the leading product for each subgroup of a form fit function class. DRP then consolidates the demands and stock of the location products by adding the demand and stock of the non-leading location products with substitute orders to the demand and stock of the leading location product. – SAP SCM 2007 Release Notes
Supersession in SAP ERP
Within SAP ECC, supersession is approximated by the Material Determination functionality. However, within SCM, SAP states that the rule based Available to Promise check does provide this functionality. In ECC product substitution functionality is called Material Determination (MD). The SAP definition of Material Determination is:
“Material determination enables the automatic substitution of materials in sales documents during sales order processing. For example, during the course of a sales promotion, the system can, during sales order entry, automatically substitute a material that has promotional packaging. A consumer product may have a special wrapper for, for example, the Christmas season. Using material determination, the system substitutes the material only during the specified period. Material determination is used for:
- Customer-specific product numbers with your own material numbers
- International Article Numbers (EANs) with your own material numbers
- Substituting discontinued materials with newer materials” – SAP Help
Interesting features of material determination
- MD happens during the sales order process
- Sales document types (A&D Contract, Repair Quotation, etc.) can be set for MD
This screen shows the connection settings between the Sales Doc Type and Material Determination
Where Should Supersession be Performed?
Supersession logic can be maintained in both the planning system and the execution system. That is both in MCA and SAP. They can be for different purposes however. A few options are:
- Planning supersession can be performed in MCA, while execution supersession can be performed in SAP ECC (for sustainment, production supersession is a different matter).
- Planning supersession can be performed in MCA with no sustainment supersession data maintained in SAP ECC. However inventory planners can still use MCA’s user interface to determine the superseeded part, and then execute the supersession in SAP.
In either case SAP will respect the supersession that is performed in SAP as it would be inherent in the New Buy List that came from MCA. The basic questions are:
- Is having the execution supersession available in SAP (allowing automated supersession within SAP ECC) worth the additional effort in configuring MD and in the continual maintenance of this supersession list in SAP?
- Is the MD functionality capable of providing similar functionality as comes with MCA? That is, is the substution functionality, which is fairly basic, and which would provide automated supersession worth maintaining instead of looking at the MCA user interface and reading supersession relationships from MCA?
Supersession in SAP Documentation
The document below from SAP is light on details.
The best write up on supersession in SAP that we have seen is at: