2.2 Bill of material

In SAP ERP, a bill of material (BOM) is a structured collection of elements. As these elements can be very different, SAP recognizes various categories of bill of material. It is not the type of presentation that determines the differentiation, but the content or use of the list. In the SAP system, the following BOM categories are available:

• Material BOM
• Document structure
• Order BOM
• Project BOM

A material BOM describes the structure of a material made from individual components or other assemblies, and represents the most frequently used category of BOM. A document structure structures complex documents. For example, the documentation for a system can consist of a manual with electrical and hydraulic circuit diagrams, as well as technical drawings that have all been stored individually. Order BOMs and project BOMs are usually lists of materials that are valid only for a specific order or project respectively. They can be used to record special features (e.g., customer-specific adjustments to the product) without changing the fundamental BOM.

A bill of material consists of the header and one or more items. The former contains basic information, such as the base quantity of the bill of material or the engineering group (laboratory/office) responsible, as well as a description of the alternative BOM and its status (active or inactive).

Every BOM item contains exactly one component. The quantity and item category (e.g., stock item or text item) of the component required to create the base quantity are also stored here, as well as other control parameters required for special applications.

You can find these control parameters in the detailed view of the BOM item. Here, on four tabs, you can enter values such as component scrap, the removal storage location, or extended texts. You can also link documents to the respective BOM item. These can be design drawings or handling instructions.

As described in Section 1.3, both the bicycle and the complete frame are new materials. In the previous section, we created the material masters and now we will define the bills of material in the ERP system. To do this, we call up transaction CS01: SAP Menu • Logistics • Production • Master Data • Bills of Material • Bill of Material • Material BOM, and enter the material number of the bicycle (ET-F-WT500), the number of the plant (1200), and the bill of material usage (1 for “production”). Next, start the transaction by pressing “Enter”. In the item overview that appears, for every BOM item, we maintain the material number of the component, item type L for a stocked material, and the quantity required for our example (see Figure 2.11). The ERP system reads the quantity unit automatically from the material master data of the component once we press “Enter”. The checkmark in the A (assembly) column shows that there is a bill of material for this item itself—the item is therefore a further assembly. By double-clicking the checkmark, we can go to this bill of material. First, however, we want to look at the header data of the new bill of material. To do this, we click the icon .

Figure 2.11: Material BOM—Item Overview

We now check that the base quantity (i.e., the number of bicycles manufactured with the quantities of the BOM items) is exactly 1 (see Figure 2.12), because that is what we drew up the bill of material for. We do not restrict the batch size range valid for this bill of material any further. In the BOM Text field, we enter Bicycle WT500 in the Dresden plant and in the Plant field, we enter 1200 for Dresden. We can then save and exit the bill of material by clicking .

Figure 2.12: Material BOM—Header Overview