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Process 153

check will determine the earliest possible delivery date. The decision to con-
duct an availability check, as well as the type and scope of the check, is based
on settings in the material master. For example, the system can be confi g-
ured to calculate availability based on current stock levels as well as planned
receipts of material from either procurement or production. In addition, the
system can create a material reservation, which reserves the needed materials
so they cannot be used to fulfi ll any other requirements.
The availability check must also take into account the amount of time
needed to perform relevant activities such as material staging, transportation
planning, loading, and goods issue. Material staging refers to preparing the
material for shipment. It involves picking the materials from their storage
locations and packing them in suitable containers. Transportation planning is
the process whereby fi rms determine how best to transport the materials to the
customer based on weight, volume, transportation mode (e.g., truck, rail), and
other variables. Loading involves moving the materials from the plant onto the
truck. Goods issue is largely concerned with recording the fi nancial impact of
shipping goods. We will discuss goods issue later in the shipping step. The time
needed to complete these steps is calculated using backward scheduling, in
which the company begins with the required delivery date and then works in
reverse order to determine when each process step must be performed. Figure
5-27 diagrams the backward scheduling process. Note that loading is preceded
by picking/packing and transportation planning, which in turn are preceded by
material staging. Signifi cantly, these steps can overlap, as the fi gure illustrates.
Consequently, the greater of these two times (transportation lead time and
pick/pack time) is included in the calculation.
Finally, creating a sales order can generate a transfer of requirements
to the material planning process. These data are used by the material planning
process to plan materials procurement and production.

Figure 5-27: Backward scheduling

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