Bill of Material Type and Category 


In the Plant Maintenance (PM) component this involves either material master records or the bills of material of technical objects.

The technical BOM category for each newly-defined BOM is the "simple BOM". If you maintain a number of technical objects which are composed of similar or identical parts, you can extend the simple BOM to a variant or multiple BOM.


BOM type or category


Bills of Material for Technical Objects

Assignment of spare parts to technical objects

Material BOM

Mapping of assemblies and object types to be maintained

Variant BOM

Maintenance of objects which are mostly composed of the same parts

Multiple BOM

Production planning


Bill of material, type

Bills of Material for Technical Objects

Bills of material (BOMs) for technical objects are used to describe the structure of a piece of equipment or functional location and to allocate spare parts for maintenance purposes to it. BOMs for technical objects can be created individually for a specific technical object or for a group of technical objects.

A BOM can be linked to a technical object in two ways:

Direct allocation is performed by directly linking one or more master records to a BOM, without inserting a material master record. If all the technical objects are identical in terms of structure, the BOM items are valid for all the allocated technical objects.

If individual materials or assemblies are only valid for certain objects, a joint BOM can still be used. In this case, the object-specific differences can be documented using variant items.

Master records for technical objects can be indirectly allocated to a BOM if the master records are linked to a material master record which contains its own material BOM via the field Construction Type. This is the case when a company has several identical technical objects grouped under one material number. This is shown in the figure below:


The following rules apply to functional locations:

When the installation of pieces of equipment is allowed for the functional location, the material number entered in the functional location master record simply indicates that only pieces of equipment with this material number can be installed in the functional location.

If the installation of pieces of equipment is not allowed, the material number entered in the functional location master record indicates that this functional location is one of several similar functional locations that are combined under this material number. Only in this case can you use the material number for indirect allocation of BOMs.

Material BOM

It is created with a direct link to a material master record. The material master record contains, amongst others, descriptive data (for example, weight and dimensions) and control data (for example, material category and industry sector).

In maintenance, material BOMS are used to depict the structure of assemblies to be maintained and object types in a company.

For more information on Engineering Change Management, refer to the SAP documentation PP - Bill of Material.

Bill of material, category

Variant BOM

If you maintain technical objects containing mostly the same parts, you can combine the individual bills of material (BOMs) for these objects to form a variant BOM.

You want to depict several engines, which all have a very similar structure. However, there are a few significant differences, which also affect the bills of material (BOMs) for the individual motors.

Create a BOM for engine 1. It contains the highest number of components that are also contained in the other engines.

Now create BOMs for the other slightly different engines. These are the so-called variants. They contain

The BOM for engine 1 and all the variants together form the BOM group "Engines".

Several technical objects which are entered as variants of one variant BOM are stored under one BOM number. You can describe all variants of a variant BOM using the BOM group (in the BOM header).

Variant BOMs require less memory space, as the identical BOM items are only saved once on the database.

A change to a BOM item, which is identical in several variant BOMs, is simultaneously performed for all affected variant BOMs.

Multiple BOM

A technical object which consists of different combinations of material is represented by a number of alternative BOMs. These alternative bills of material differ only slightly, mostly in the quantity of certain materials in certain items or small variances in materials.

Multiple bills of material are used in production planning and have little or no use in plant maintenance.