Supersession Chains for PP/DS
Definition
Chain of products that can replace each other.
Use
Based on a supersession chain,
Production Planning and Detailed Scheduling
(PP/DS) can take the limited time validity of a product and its substitution by other products into consideration during planning and order processing.
Structure
Structure of a Supersession Chain for PP/DS
PP/DS only supports linear supersession chains. In a linear supersession chain, each product in the supersession chain can have only one predecessor and one successor. The products in a supersession chain are therefore linked by 1:1 relationships. Supersession chains in which a product has several successor products (1:N), or several products have one successor product (N:1) are not permitted. Substitution rules, which contain conditions for substitutions, are not relevant to PP/DS. Restricted interchangeability is therefore not supported. In addition, the supersession chain and its products have to fulfill the following prerequisites:
The products in the supersession chain have to be different; that is, a supersession chain such as A
B
A is not permitted
The supersession chain may not contain any assemblies.
A product can only be contained in one supersession chain
The base unit of measure must be the same for all products in a supersession chain
A supersession chain may not contain any configurable products
The shelf life data must be the same for all products in a supersession chain.
At every point in time, exactly one product in the supersession chain is valid. Each product is only valid until a specific date – the discontinuation date – and is then replaced by its successor product. The system may no longer procure a product after its discontinuation date. However, there may still be uncovered requirements or surplus stock and fixed receipts for the discontinued product. PP/DS planning has to use up the surplus stock and fixed receipts – if this is permitted – and forward the uncovered product requirements to the valid successor product (see use-up strategy ).
To define a supersession chain, you have to create an interchangeability group with the group type
supersession chain
and define the direction of interchangeability between the products in the chain.
For example, in the case of a supersession chain with the form A
B
C, you have to create the direction of interchangeability A
B and B
C.
You define the discontinuation date of a product indirectly by specifying the date as of which the successor product is valid.
Therefore, in the substitution relationship A
B you enter the validity start date of B.
Direction of interchangeability
Between a product and its successor product, the interchangeability directions
forward interchangeable
or
fully interchangeable
are available.For the interchangeability direction
forward interchangeable (A
B), the substitution can only be made in one direction.
Therefore, if there is a requirement for product A, this can also be covered by product B.The reverse is not true, however: Product A cannot replace product B if there is a requirement for B.For the interchangeability direction
fully interchangeable
(A B), substitution is possible in both directions, meaning that product B can replace product A, and vice versa.
Integration
In order that the system can forward stock, fixed receipts, and requirements for a discontinued product to a valid successor product, if necessary, it must always plan all products in a supersession chain together during procurement planning. If, in SAP APO, you assign an interchangeability group for a supersession chain to a location, the system automatically creates a planning package (planning package type 001) for these products. The system enters this planning package in the location product masters of the products involved. This makes necessary the common planning of the products in the MRP planning run.
The system generates the planning-relevant event
Change the product master in SAP APO
for this change to the location product master. The system also generates this event if you change the supersession chain and thus also the planning package.