BOM ( Bill of a material )

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  • Phantom Assemblies
    • BOM Explosion with Phantom Assemblies
    • Costing
  • BOM attributes 
    • BOM Status
    • Discontinued Parts
    • BOM Items Relevant for Production
    • Alternative Items
    • Multiple BOMs
    • BOM Explosion Number (Fixed Key Date)
    • Period/Area of Validity of BOMs
    • BOM Usage
    • BOM application 
  • Sales BOM
  • BOM Explosion and Determining Dependent Requirements
  • Data model 
  • Tools for mass changes
    • Engineering workbench (CEWB)
    • CS20


Phantom Assemblies

SAP phantom assemblies reduce master data maintenance. Since several items are grouped by a phantom assembly, we do not need to maintain all these items again and again. Also, changes in items can be done inside BOM of the phantom assembly, so that changes are applicable to the high-level BOMs where this phantom assembly is used. 

The phantom assembly represents a logical grouping of materials . These materials are grouped together from the construction point of view and are all maintained together. From the production point of view, however, these materials are normally not assembled .

BOM Explosion with Phantom Assemblies

You have entered a special procurement key for Phantom assembly (50) in the Special procurement field in the material master ( MRP 1 view) for the assembly.

If a BOM item is a phantom assembly , the dependent requirements of the higher-level assembly are directly passed on to the components of the phantom assembly . The phantom assembly itself is still not taken into account.

(!) We can stop the phantom assembly behavior at the BOM item level by using phantom assembly off indicator. This will override the special procurement type 50 setting and will make it behave as a normal assembly. This business function can be used in cases where the same assembly acts as a phantom item in some of the final assemblies and as a normal assembly in some other final assemblies.

Costing

During costing, SAP system explodes BOM and calculates the planned costs for all the material components in the phantom assembly. Phantom assembly’s material components are displayed and updated in the cost estimate of the higher-level material. The results of the cost estimate will be updated with a reference to the phantom assembly.

No BOM explosion or costs and requirements for phantom assembly

Final confirmation is executed for the production order， but the reservation of phantom component remains. You can see the unexpected reservation in t-code MD04.

Create a production order with phantom assembly as component and release the order in t-code CO01.
Execute final confirmation for the order in t-code CO11N.
Check if the reservation of phantom assembly exist in t-code MD04.

You can use report CORU_PHANT_REDUCT to clear the reservation for phantom assembly. This report adjusts the withdrawal quantity of the parent phantom according to the component's withdrawal quantity.


Using phantom assemblies in PP-PI

A phantom assembly should have exactly one alternative BOM. The usage of several alternative BOMs in a phantom assembly is not supported in PP-PI in the explosion.

BOM attributes 

BOM Status

The BOM status specifies whether a bill of material is active or inactive for different organizational areas.

Discontinued Parts

You can determine in engineering/design that a material is to be replaced by another one at a certain point in time. When replacing a component with another , however, the stock of the old material should be used up before the new one is introduced in order to avoid dead stock.
It may be necessary to replace one part for another if:
  • one part is replaced by a more technically advanced part
  • an expensive part is replaced by a less expensive part

BOM Items Relevant for Production

In order to indicate the relevance of an item for production, choose the tab index Status/lng text in the item overview screen of the BOM and select the Production relevant field.

Alternative Items

If you would like to use one or several alternative components in an assembly, you can enter these in the bill of material and combine them by grouping the alternative items . These alternative items can then be taken into account when exploding the BOM during the planning run.

Prerequisites
  • You have entered the materials that can be used as alternatives within an assembly in the BOM as components.
  • You have entered the same grouping key for all alternative items in the item data in the Alternative item group field, thus combining the alternatives (see below).
  • You have entered the usage probability on the Alternative Item Data screen. This percentage specifies the probability with which the component will be used for the assembly.
The alternative items can be taken into account in MRP according to the defined usage probability or can be defined in the BOM purely for information purposes for the employee.

Multiple BOMs

For multiple BOMs, you must specify which alternative BOM should be selected by the system during the planning run.

You have determined the procedure to be used for selection for an assembly in the material master ( MRP 4 view) in the Selection method field.
  • Selection using order quantity (lot size)
    • During the planning run, the system checks whether a valid alternative BOM exists for the order quantity (lot size) in the planned order. The valid alternative is exploded and dependent requirements are created for the components.
  • Selection using explosion date
    • If the system does not find a valid or an appropriate alternative BOM for the explosion date, it uses the BOM with the appropriate lot size.
  • Selection using production version
    • During the planning run, the system checks whether a production version matches the quantity and the date of the planned order. If it finds a valid production version, the BOM with the respective usage and alternative is exploded and dependent requirements are created for the components.

BOM Explosion Number (Fixed Key Date)

If you want to ensure that for a certain production unit, the BOM structure is always exploded with the same date , you can allocate a BOM explosion number to the planned order (or for make-to-order production it can be directly allocated to the sales order).
Prerequistes:
  • You have created a BOM explosion number.
  • You have entered the BOM explosion number in the sales order, or entered it when creating the planned independent requirements or when manually creating/changing planned orders.
By means of the BOM explosion number , you can define a common explosion date ( fixed key date ) for all BOM levels. BOM explosion is then carried out with this fixed key date for all levels.

Period/Area of Validity of BOMs

During the planning run, the system tries to determine the valid bill of material that is suitable for the planning situation.

Area of Validity
For material requirements planning, the BOM must be maintained in the planning plant . If production is carried out in a different plant from the planning plant, then the BOM must also be maintained in this other plant.

Validity Period
The validity period represents the time period during which the bill of material is valid. This time period is defined by entering a Valid from date and a Valid to date .

BOM Usage

By means of BOM usage, you can manage separate bills of material for various internal organizational areas ( engineering/design, production, costing , and so on). The main differences in the BOM structure result from the different responsibilities in the various organizational areas, which all process different item data.

In Customizing for MRP, you have defined a sequence for the possible BOM usages for each plant in the IMG activity Define BOM and routing selection using the BOM selection ID .

The system first searches for a valid BOM or alternative BOM for the BOM usage with the highest priority. If the system does not find a valid BOM or alternative BOM in the selected BOM usage, then the BOM usage with the next-lowest priority is selected. The system then looks for valid BOMs for this BOM usage.
  • The design BOM includes all the components of the product and their technical data from the design point of view. This BOM is generally not linked to any order.
  • The production BOM includes all the items required from the production and assembly point of view. To assemble a product, you only require items that are relevant to production, which contain process data.
  • The costing BOM describes the product structure and is used to automatically determine the costs of the materials required for a product. Items that are not relevant to costing are not included in the costing BOM.
Each area (for example, production) creates its own BOM that contains application-specific data, instead of using one BOM for the entire company. Each area can target the BOM explosion to find only the data that is relevant.
  • Priorität für Stücklistenauflösung über CS12 (Anwendung)
  • Regeln für die Stücklistenauswahl ( T-Code OPPQ) + SM30: V_TCS41
  • Diese Auswahl wird auch in der Stücklistenanwendung ( T-Code OPJM ) verwendet
  • Activate it in OS24 and in OS14 as it checks the permission to use the Usage for header and item levels

Types 

Sales BOM

When you enter the material number of a bill of materials that is relevant for sales order processing, the system displays the material that describes the whole bill of materials as a main item. The individual components are displayed as lower-level items.

We can control pricing, inventory and delivery related indicator either on main item level or sub item level. 

If we use ERLA item category group in finished goods material master data, it will control pricing and inventory at header level and sub items will work as text items. For sub item level control you use item category group LUMF.

If you want the system to carry out pricing, inventory control, and delivery processing at the component level, enter LUMF in the Item category group field of the Sales: sales org. 2 screen in the material master record of the finished product. In this case, only the components are relevant for delivery. During processing the system automatically creates a delivery group. The latest delivery date among all the components becomes the delivery date for the entire delivery group.

Use cases:
  • Free goods: in order to provide several free goods materials, we can use a Sales BOM. BOM usage 5.
    • Main item: Billing Relevance A, Structure scope A, Pricing X, Application SD01
    • Subitme: ------
  • Pricing at heder and item level
    • Sell a component or a material in a sales document
VDM CS_MODEL

BOM application 

BOM application is maintained in order type dependent parameter (T code OPL8). This setting is a combination of plant and order type which we will enter at the time of order creation.

Now if you see the cust setting of BOM application, you will get like this,

From this setting you will get the selection ID(T code OS30). Now as per the selection ID and priority the usage will be selected (T code OS31).



This is the way how the BOM will be selected with application.

This is valid for production order. If no value is maintained in order type dependent parameter, system will check the plant parameter and take the default value for selection (T code OPPQ).

BOM Explosion and Determining Dependent Requirements

Determining the Valid BOM

  1. The system checks which BOM usage in the plant has the highest priority (see BOM Usage).
  2. For this usage, the system then checks whether there is a valid BOM for the explosion date (see Period / Area of Validity of BOMs ). The explosion date is the planned start date of the planned order.
  3. If, for a particular production unit, you want to ensure that the total BOM structure is always exploded using the same explosion date and have assigned a BOM explosion number and fixed key date to the sales order, the planned independent requirement, or the planned order, the system chooses the BOM that is valid for this date (see BOM Explosion Number (Fixed Key Date)).
  4. The system checks whether the chosen BOM has the status active for MRP (see BOM Status).
  5. If a multiple BOM exists, the system checks which alternative BOM corresponds to the preconditions of the alternative selection.

2541704 - Wrong BOM selection in a Purchase Order

While creating subcontracting purchase order with transaction ME21N, the system does not allows to select the BOM. System defaults the first BOM and it´s not possible to change to an alternative BOM.

If several alternative BOMs exist, there is no possibility of selecting the desired BOM interactively.

Selection can be controlled via the following mechanisms:
  •  Selection by quantity: A lot size interval for which the BOM is valid can be entered in the BOM header. A prerequisite is that the Selection method indicator is not set in the material master record (MRP 4 view).
  • Selection by date: Can be set in the IMG under Production -> Basic Data -> Bill of Material -> Alternative Determination -> Define Alternative Determination for Multiple BOMs (transaction OS32). A prerequisite is that the Selection method indicator the is set to 1 in the material master record (MRP 4 view).
  • Selection by production version: Can be used if the same material has different BOMs with different suppliers. You create different production versions in the material master record of the assembly (pushbutton in MRP 4 view) and assign an alternative BOM to the versions on the detail screen. You then enter the valid production version in the info record in each case.


If no selection mechanism has been defined and several alternatives exist, the first one found is pulled.

Data model 

  • STKO BOM header
  • STZU Permanent BOM data
  • STPO BOM item
    • STLTY BOM category
    • STLNR Bill of material
    • STLKN BOM item node number
    • STPOZ Internal counter
  • STAS BOMs - Item Selection
  • STPU BOM Subitems
  • STPF Structure tree of the exploded BOM
  • STVB Billls of Material - Serialization of Posting
  • STPN BOM Follow-Up Control


Tools

Engineering workbench (CEWB)

CS20



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