236
Chapter Six Process Selection and Facility Layout
Inputs
Outputs
FIGURE 6.1
Process selection and capacity
planning influence system
design
Forecasting
Facilities and
equipment
Capacity
Planning
Product and
service design
Layout
Process
Selection
Technological
change
Work
design
INTRODUCTION
Process selection refers to deciding on the way production of goods or services will be orga-
nized. It has major implications for capacity planning, layout of facilities, equipment, and
design of work systems. Process selection occurs as a matter of course when new products or
services are being planned. However, it also occurs periodically due to technological changes
in products or equipment, as well as competitive pressures. Figure 6.1 provides an overview
of where process selection and capacity planning fit into system design. Forecasts, product
and service design, and technological considerations all influence capacity planning and pro-
cess selection. Moreover, capacity and process selection are interrelated, and are often done in
concert. They, in turn, affect facility and equipment choices, layout, and work design.
How an organization approaches process selection is determined by the organization's pro-
cess strategy. Key aspects include
Capital intensity: the mix of equipment and labor that will be used by the organization.
Process flexibility: the degree to which the system can be adjusted to changes in process-
ing requirements due to such factors as changes in product or service design, changes in
volume processed and changes in technology.
PROCESS SELECTION
Process choice is demand driven. Three primary questions bear on process selection:
1. How much variety in products or services will the system need to handle?
2. What degree of equipment flexibility will be needed?
3. What is the expected volume of output?
Answers to these questions will serve as a guide to selecting an appropriate process.
Process pes
There are five basic process types: job shop, batch, repetitive, continuous, and project.
Job Shop. A job shop usually operates on a relatively small scale. It is used when a low
volume of high-variety goods or services will be needed. Processing is intermittent; work
includes small jobs, each with somewhat different processing requirements. High flexibility
using general-purpose equipment and skilled workers are important characteristics of a job
shop. A manufacturing example of a job shop is a tool and die shop that is able to produce
Chapter Six Process Selection and Facility Layout
237
A job shop process: A midwestern hospital medical team
performs a diagnostic procedure involving a cardiac
catheterization
A batch process: Menu items are prepared in batches, in the
kitchen of the Spago Restaurant in the Forum at Caesar's
Palace, Las Vegas, Nevada
A repetitive process: Motorcycles on an assembly line with
parts added in a sequential order:
A continuous process: An oil refinery performs a continuous
process, mixing and separating crude oil into gas, fuel oil,
chemicals, and many other products.
one-of-a-kind tools. A service example is a veterinarian's office, which is able to process a
variety of animals and a variety of injuries and diseases.
Batch. Batch processing is used when a moderate volume of goods or services is desired,
and it can handle a moderate variety in products or services. The equipment need not be as
flexible as in a job shop, but processing is still intermittent. The skill level of workers doesn
need to be as high as in a job shop because there is less variety in the jobs being processed.
Examples of batch systems include bakeries, which make bread, cakes, or cookies in batches;
movie theaters, which show movies to groups (batches) of people, and airlines, which carry
planeloads (batches) of people from airport to airport. Other examples of products that lend
themselves to batch production are paint, ice cream, soft drinks, beer, magazines, and books.
Other examples of services include plays, concerts, music videos, radio and television pro-
grams, and public address announcements.
238
Chapter Six Process Selection and Facility Layout
Repetitive. When higher volumes of more standardized goods or services are needed, repet-
itive processing is used. The standardized output means only slight flexibility of equipment is
needed. Skill of workers is generally low. Examples of this type of system include production
lines and assembly lines. In fact, this type of process is sometimes referred to as assembly.
Familiar products made by these systems include automobiles, television sets, pencils, and
computers. An example of a service system is an automatic carwash. Other examples of ser-
vice include cafeteria lines and ticket collectors at sports events and concerts. Also, mass
customization is an option.
Continuous. When a very high volume of nondiscrete, highly standardized output is
desired, a continuous system is used. These systems have almost no variety in output and,
hence, no need for equipment flexibility. Workers' skill requirements can range from low
to high, depending on the complexity of the system and the expertise workers need. Gener-
ally, if equipment is highly specialized worker skills can be lower. Examples of nondiscrete
products made in continuous systems include petroleum products, steel, sugar, flour, and
salt. Continuous services include air monitoring, supplying electricity to homes and busi-
nesses, and the Internet.
These process types are found in a wide range of manufacturing and service settings. The
ideal is to have process capabilities match product or service requirements. Failure to do so
can result in inefficiencies and higher costs than are necessary, perhaps creating a competitive
disadvantage. Table 6.1 provides a brief description of each process type along with advan-
tages and disadvantages of each.
Figure 6.2 provides an overview of these four process types in the form of a matrix, with
example for each process type. Note that job variety, process flexibility, and unit cost are
highest for a job shop and get progressively lower moving from job shop to continuous pro-
cessing. Conversely, volume of output is lowest for a job shop and gets progressively higher
moving from job shop to continuous processing. Note, too, that the examples fall along
the diagonal. The implication is that the diagonal represents the ideal choice of processing
system for a given set of circumstances. For example, if the goal is to be able to process a
small volume of jobs that will involve high variety, job shop processing is most appropriate.
For less variety and a higher volume, a batch system would be most appropriate, and so on.
Note that combinations far from the diagonal would not even be considered, such as using
job shop for high-volume, low-variety jobs, or continuous processing for low-volume,
an
TABLE 6.1
Types of processing
Job Shop
Repetitive/
Assembly
Batch
Continuous
Description
Customized
goods or
services
Standardized
goods or
services
Highly standardized
goods or services
Advantages
Able to handle a
wide variety
of work
Semi
standardized
goods or
services
Flexibility, easy
to add or
change
products or
services
Moderate cost
per unit,
moderate
scheduling
complexity
Low unit
cost, high
volume,
efficient
Very efficient, very
high volume
Disadvantages
Slow, high cost
per unit,
complex
planning and
scheduling
Low flexibility,
high cost of
downtime
Very rigid, lack of
variety, costly to
change, very high
cost of downtime
Chapter Six Process Selection and Facility Layout
239
Product or Service and Flexibility Variety and Equipment Flexibility
High
Moderate
Low
Very low
FIGURE 6.2
Volume, variety, and flexibility
of operations processes
Low or very
low volume
Job Shop
repair shop
emergency room
Moderate
volume
Batch
commercial bakery
classroom lecture
High volume
Repetitive
assembly line
automatic car wash|
Very high
volume
Continuous Flow
petroleum refining
water treatment
high-variety jobs, because that would result in either higher than necessary costs or lost
opportun
Another consideration is that products and services often go through life cycles that begin
with low volume, which increases as products or services become better known. When that
happens, a manager must know when to shift from one type of process (e.g., job shop) to the
next(e.g., batch). Of course, some operations remain at a certain level (e.g., magazine pub-
lishing), while others increase or decrease as markets become saturated) over time. Again, it
is important for a manager to assess his or her products and services and make a judgment on
whether to plan for changes in processing over time.
All of these process types (job shop, batch, repetitive, and continuous) are typically ongo-
ing operations. However, some situations are not ongoing but instead are of limited durations.
In such instances, the work is often organized as a project.
Project. A project is used for work that is nonroutine, with a unique set of objectives to be Project A nonrepetitive set
accomplished in a limited time frame. Examples range from simple to complicated, including of activities directed toward a
such things as putting on a play, consulting, making a motion picture, launching a new prod- unique goal within a limited time
uct or service, publishing a book, building a dam, and building a bridge. Equipment flexibility frame.
and worker skills can range from low to high.
The type of process or processes used by an organization influences a great many activities
of the organization. Table 6.2 briefly describes some of those influences.
Process type also impacts supply chain requirements. Repetitive and continuous pro-
cesses require steady inputs of high-volume goods and services. Delivery reliability
terms of quality and timing is essential. Job shop and batch processing may mean that
suppliers have to be able to deal with varying order quantities and timing of orders. In
some instances seasonality is a factor, so suppliers must be able to handle periodic large
demand.
The processes discussed do not always exist in their “pure" forms. It is not unusual to
find hybrid processesprocesses that have elements of other process types embedded
in them. For instance, companies that operate primarily in a repetitive mode, or a con-
tinuous mode, will often have repair shops (i.e., job shops) to fix or make new parts for
equipment that fails. Also, if volume increases for some items, an operation that began,
say, in a job shop or as a batch mode may evolve into a batch or repetitive operation.
This may result in having some operations in a job shop or batch mode, and others in a
repetitive mode.
SUPPLY CHAIN
240
Chapter Six Process Selection and Facility Layout
TABLE 6.2 Process choice affects numerous activities/functions
Activity
Function
Job Shop
Batch
Repetitive
Continuous
Projects
Routine
Cost estimation
Cost per unit
Equipment used
Fixed costs
Variable costs
Labor skills
Marketing
Difficult
High
General purpose
Low
High
High
Promote
capabilities
Somewhat routine
Moderate
General purpose
Moderate
Moderate
Moderate
Promote
capabilities, semi-
standardized goods
and services
Moderately complex
Routine
Low
Special purpose
High
Low
Low
Promote
standardized
goods/services
Low
Special purpose
Very high
Very low
Low to high
Promote
standardized
goods/services
Simple to complex
Very high
Varied
Varied
High
Low to high
Promote
capabilities
Scheduling
Complex
Routine
Routine
Complex, subject to
change
Varied
High
High
Low
Low
Work-in-process
inventory
Morton Salt
OPERATIONS TOUR
Introduction
The salt is stored in silos until it is needed for production, or it
Morton Salt is a subsidiary of Morton International, a manufac-
is shipped in bulk to industrial customers. Conveyors move the salt
turer of specialty chemicals, air bags, and salt products. The Mor-
to each of the four dedicated production areas, one of which is
ton salt-processing facility in Silver Springs, New York, between round can production. (See diagram.) The discussion here focuses
Buffalo and Rochester
, is one of six similar Morton salt-processing exclusively on round can production.
facilities in the United States. The Silver Springs plant employs
about 200 people, ranging from unskilled to skilled. It produces salt Round Can Production
products for water conditioning, grocery, industrial, and agricul- Annual round can production averages roughly 3.8 million cans.
tural markets. The grocery business consists of 26-oz. round cans Approximately 70 percent of the output is for the Morton label,
of iodized salt. Although the grocery business represents a rela- and the rest is for private label. There are two parallel, high-
tively small portion of the total output (approximately 15 percent), speed production lines. The two lines share common processes
it is the most profitable.
at the beginning of the lines, and then branch out into two iden-
tical lines. Each line is capable of producing 9,600 cans per hour
Salt Production
(160 cans per minute). The equipment is not flexible, so the pro-
The basic raw material, salt, is obtained by injecting water into duction rate is fixed. The operations are completely standard-
salt caverns that are located some 2,400 feet below surface. ized; the only variable is the brand label that applied. One line
There, the salt deposits dissolve in the water. The resulting brine requires 12 production workers, while both lines together can
is pumped to the surface where it is converted into salt crystals. be operated by 18 workers because of the common processes.
The brine is boiled, and much of the liquid evaporates, leaving Workers on the line perform low-skilled, repetitive tasks.
salt crystals and some residual moisture, which is removed in The plant produces both the salt and the cans the salt is pack-
a drying process. This process is run continuously for about six aged in. The cans are essentially a cylinder with a top and a bot-
weeks at a time. Initially, salt is produced at the rate of 45 tons tom; they are made of cardboard, except for a plastic pour spout
per hour. But the rate of output decreases due to scale buildup, in the top. The cylinder portion is formed from two sheets of chip
so that by the sixth week, output is only 75 percent of the initial board that are glued together and then rolled into a continuous
rate. At that point, the process is halted to perform maintenance tube. The glue not only binds the material, it also provides a mois-
on the equipment and remove the scale, after which, salt produc- ture barrier. The tube is cut in a two-step process: it is first cut
tion resumes.
(continued)
Purchase answer to see full
attachment