Notes
204
The number ten represents ten items moving from one department
to another. The items could be pieces
of wood used to make furniture,
stock purchase transactions, or even people moving from one point to
another.
The matrix does not consider movements from department 1
to department 1,2 to2, and so on. These interdependent moves would
be considered as part of the layout within the department. As shown
in the matrix in Exhibit, product movement follows the same sequence
through the departments: 1-2-3-4-5. The flows
between any other pair
of departments or in any other sequence are zero. As a result, the layout
that minimizes the costs of moving between departments is simple—it
follows the product’s sequence of operations. This is why a continuous
flow process and assembly lines are said to have product-oriented layouts.
Even in cases where other minor product movement exists, the
dominant flow will govern the layout. It is only when these other flows
become significant that the process is no longer a continuous flow or an
assembly line. When many different paths or sequences occur,
the process
takes on characteristics typical of a job shop.
Because the layout for continuous flow processes follows the
product’s sequence of operations, the technical aspects of the process
selection ultimately dictate the layout. For example when crude oil is
refined to make various products, including gasoline, diesel fuel,
kerosene,
and heating oil, the process follows a sequence of steps.
In the first step, distillation, crude oil is heated to 700 degrees F.A
mixture of vapor and unvaporized oil passes from the heating furnace into
a fractioning column that contains perforated trays. The vapor condenses
at different trays, which means that different products come out of the
column at different levels. Gasoline is lighter than heating oil and therefore
condenses at a different (higher) level.
In
the next step, alteration, the remaining heavy oils, which have
little economic value, are processed so their chemical structure is altered.
These elements are recombined to make high-value products such as
gasoline. In the final step,
impurities, such as sulfur, are removed from
the products. The layout of the oil refinery should follow the processing
Notes
205
requirements so the equipment for distillation is close to the equipment
for alteration, which, in turn, is close to the equipment for purification. In
this way, material-handling costs are reduced.
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