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192 CHAPTER 6 The Production Process

sequence, and many operations can be completed in a variety of sequences.
This routing, for example, displays a standard sequence, in which Operation 1 is
performed prior to Operation 2, and an alternate sequence, in which Operation
2 is performed fi rst.
The right side of Figure 6-10 shows the routing for GBI’s deluxe touring
bike. The routing indicates that operations needed to produce this bike can be
performed in only one possible (standard) sequence. For example, the seat is
attached to the frame fi rst, followed by the handle bar.
GBI uses prebuilt components such as the brake kit and pedal assembly
that it purchases from vendors. If GBI were to manufacture these two com-
ponents in-house, then it would have to assemble them from raw materials
before it attached them to the bike frame. Signifi cantly, GBI would not have to
build either of these components before the other. Instead, it could build them
simultaneously, or in parallel. This process is referred to as parallel sequences.
As with alternate sequences, parallel sequences are included in the routing.
Given all these options, when and how does a company decide which
approach to utilize? The answer is that it selects the appropriate sequence
when it actually carries out the production. It bases this decision on factors
such as the desired quantities of the product and the equipment and other
resources that are available at the time of production.
As we discussed in the previous section, operations are completed in
work centers. Thus, a work center must be assigned to an operation. Recall
that work centers have standard values keys and formulas to calculate the time
needed to complete the steps in each operation. There are three basic time
elements in the production process: setup time, processing time, and tear-
down time. Setup time involves confi guring the work center and equipment.
Processing time can refer both to machine time, which involves the use of a
machine for an operation, and to labor time, which is the human work needed
to perform the operation. Finally, during teardown time, workers return the
machines to their original state—that is, before setup.
Going further, these time elements can be either fi xed or variable. Fixed
time elements are independent of how many units of the material are produced,
whereas variable time elements represent the time needed to produce one
unit of the material. For example, material staging, the operation whereby the
component materials are moved from storage and prepared for use, takes
the same amount of time for 10 bikes as for 15 bikes. In contrast, the time needed
to build the wheel assembly depends on how many assemblies are being pro-
duced. Figure 6-11 illustrates the relationship between Operation 80 (test bike)
and INSP1000, the inspection work center. It indicates the setup, machine, and
labor times for the operation. Recall that INSP1000 has two capacities—machine
and labor (001 and 002 in the fi gure). When more than one capacity is available
in a work center, the company uses the scheduling basis to determine which
capacity it will utilize to complete the production order.
Figure 6-12 illustrates the routing for GBI’s deluxe wheel assembly. The
fi gure identifi es the required operations, the work center where the operation
will be completed, the times associated with the operation, and the compo-
nents assigned to each operation. The wheel assembly has three operations—
stage material, assemble components into wheel assemblies, and move to
storage—all of which are completed in work center ASSY1000. Wheels are
assembled in batches or lots of 50. It takes 5 minutes to stage the materials for
50 wheels, 3 minutes to assemble each wheel, and another 5 minutes to move

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