In the last blog about Variant Configuration, we talked about the variant BOM (or BOM group), which is shared by many materials. There is, however, another construct in SAP which has a similar name but a different purpose: the group BOM. In the following article, you will learn what it is used for and how it is created and maintained.
Let’s return to our simple scenario at Super Awesome Bikes (to review the scenario in my last article, click here). Suppose that the Wayfarer, their road bike model, has become incredibly popular. Given the increase in both their budget and the demand for this model, a new plant is built and staffed to exclusively produce more Wayfarers. As you can guess, this is a situation where components would have to be extended to another plant and a BOM would have to exist for the material and plant combination. This is a basic example. but companies usually manage a lot of plant and products. If the person in charge of the BOMs creates a new BOM copy for each combination, it could potentially make maintenance tedious should a component need to be changed. Indeed, the BOM for each plant would have to be individually maintained, just like the BOM for each individual material variant had to be maintained in my last article’s example.
Instead of creating one BOM for each material and plant combination, it would be much wiser for example to simply assign the existing Wayfarer's BOM to the other plant, without creating copies of it. In that case, that would make it a group BOM, and maintaining it would change the BOM in all assigned plants at once. In the last article, we saw that the variant BOM (or BOM group) is useful when producing several variants of a material for which many components are shared. The group BOM of a material, however, is useful when producing that material with the exact same components in different plants.
NOTE: In SAP, you will see the term BOM group rather than variant BOM. However, there is also the concept of group BOM in SAP (which we are viewing now). Since BOM group and group BOM are easily confused and have different applications, I personally prefer to use the term variant BOM when talking about BOM groups.
Creating a group BOM
In order to create a group BOM, which is in fact assigning a BOM to other plants, transaction CS07 (create plant assignment) is to be used. Note that you can change BOM plant assignments using CS08 and view them via CS09. The reason why CS07 is used rather than CS01 is that no new copy of the BOM needs to be created. Instead, we are simply assigning the same BOM (and all of its components) to another plant. Returning to the Super Awesome Bikes scenario, let’s take care of the BOM maintenance in order to be able to manufacture the Wayfarer in the newly built plant. Creating a new plant assignment is as simple as firing up the transaction, entering the material, plant and usage and selecting which new plant to assign it to (if the components in the BOM have already been extended to the plant). In this example, we select the BOM for the Wayfarer in plant EL01 and choose to assign it to plant EL02. For a detailed hands-on video about group BOM creation and usage, please scroll to the bottom of the article.
Group BOMs and variant BOMs (BOM groups) do mix
As explained earlier, the group BOM and the variant BOM serve different purposes. That does not mean, however, that group BOMs and variant BOMs don’t mix. In my last article, we created a variant BOM for Super Awesome Bikes which had components shared among all three bike models (and also some parts specific to each). This variant BOM had been created for plant EL01. We have already taken care of extending the specific BOM of the Wayfarer in plant EL01 to plant EL02. In doing so, we now have a BOM that is both a variant BOM and a group BOM! It is a variant BOM because accessing BOM group BIKES via CS05 allows to maintain components shared among the Mountaineer, Wayfarer and Slowpoke bikes in plant EL01. However, it is also a group BOM because the BOM of one of the bike variants, the Wayfarer, has been shared by plants EL01 and EL02 via transaction CS07.
Following this two-part article series, you can probably see that there is more to Bills of Materials than just a single material, plant and usage combination. Variant BOMs can be created to provide flexibility and ease of maintenance when producing similar product variants, while group BOMs are used to have a BOM tied to more than one plant with no additional BOM creation. By using these constructs on their own or together, you can reduce the clutter in your data and save time in your BOM maintenance.
For a video guide, please see the video below: