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Master Data 183

Figure 6-2: Single- and multi-level BOMs

In contrast, the BOM for a Boeing 747 aircraft is exceedingly complex, con-
taining more than 6 million materials. In addition, BOMs can be either single
level or multi-level. A single-level BOM contains only one level in the hierar-
chy, whereas a multi-level BOM has more than one. An aircraft, for example,
may have more than 50 levels in its BOM.
BOMs in SAP ERP are defi ned as single level. However, SAP ERP can
construct multi-level BOMs by nesting several single-level BOMs. Nesting
refers to a hierarchy in which a component in a bill of material has its own
bill of material. This structure is illustrated in Figure 6-2, where a multi-level
BOM is comprised of three single-level BOMs. The BOM for the fi nished
good shows three items: two semifi nished goods and one raw material. In turn,
each semifi nished good has a BOM consisting of one or more raw materials.
(The raw materials have no BOM and are acquired from an external source.)
Signifi cantly, a BOM is defi ned for a material at the plant level. In other
words, different plants may use a different BOM to produce the same mate-
rial. This is the case when some of the materials used in producing the material
are different. For example, one plant may use a slightly different bolt than
another plant in making a fi nished good.
Recall from Chapter 1 that GBI makes deluxe and professional tour-
ing bikes. The BOM for the touring bikes (Figure 6-3) displays the materi-
als required to assemble the bikes. The professional touring bikes include a
professional wheel assembly made from aluminum wheels, while the deluxe
touring bikes include a deluxe wheel assembly made from carbon composite
wheels. The frames for both the professional and deluxe bikes are made of
carbon composite material and come in three colors—red, black, and silver.
GBI also manufactures men’s and women’s off-road bikes using alumi-
num frames and aluminum wheels. The frame for the men’s bikes is a differ-
ent size than the frame for the women’s bikes. The BOM for off-road bikes is
shown in Figure 6-4.
Figure 6-3 and Figure 6-4 represent multi-level BOMs. In both fi gures,
the wheel assembly is a semifi nished good that is manufactured using three
raw materials. The other component materials are all raw materials. Should

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