CHAPTER 6
PROCESS SELECTION AND FACILITY LAYOUT
Teaching Notes
After design of product, a process type should be selected for it, mainly depending on the volume and
design. Facility Layout involves physical placement of departments and/or arrangement of equipment
within a plant or a service facility. A good layout will possibly lead to smooth flow of material, reduction
of inventories, effective utilization of space.
The material in this chapter can be divided into four areas:
1.
Process types, selection, design, and automation.
2.
Types of layouts.
3.
Line balancing.
4.
Designing process layouts.
Reading: Tour de Force
Answers to Questions:
1.
The Viper/Prowler assembly plant is much smaller than typical automobile assembly plants. The
plant covers 392,000 square feet of space as opposed to other typical auto assembly plants that
cover from 2 million square feet to 5 million square feet of space.
The production capacity of the Viper plant is much less than a typical automobile assembly line.
The Viper plant's daily production capacity is 13 Vipers and 20 Prowlers compared to large
automobile assembly plants that can manufacture 1000 vehicles per day.
While most large automobile plants require 2000 or more workers, the Viper plant employs only
260 employees.
The Viper plant employs skilled "craftsman" workers. Typical auto assembly plants use workers
to do repetitive work with little skill required.
There are no robots or automation in the Viper plant while most auto assembly plants have high
levels of automation.
The Viper plant uses early 20th century manual assembly techniques on two manual, parallel,
relatively short (12 work stations and 720 feet long) assembly lines with generous idle time built
in. Typical assembly lines usually involve the use of robots, large number of workstations and
very little idle time.
This assembly plant, speed of line is lower (45 minute stops at each work station vs. approx. 1
minute in most other assembly plants).
2.
The reasons for not having robots or other high level automation include the following:
There seems to be more customization here making it difficult to use robots. Also, robots are
usually used for welding, which is not used for aluminum bodies of Prowler and Viper.
Chrysler Corporation wants to portray a high quality image of two handcrafted automobile
models that is generally more expensive and appealing to high-income individuals. The personal
attention to the customers is part of the marketing package associated with both products.
The company also wants to draw attention to this facility and the two car models (Viper and
Prowler) manufactured at this facility because it is an unusual and attractive automobile
Instructor’s Manual, Chapter 6
77
manufacturing facility. Chrysler Corporation is hoping that not only will it draw attention to the
two hand-crafted automobile models produced within the facility but also possibly improve the
general goodwill associated with the company.
Answers to Discussion and Review Questions
1.
2.
3.
4.
78
Process selection refers to the ways organizations choose to produce or provide their goods and
services. It involves choice of technology, type of processing, and so on. These choices have
important implications for layout of facilities, equipment choices, and the design of work
systems.
There are five basic process types:
a. Job-shop: Job-shop is used when a low volume and a large variety of goods or services are
needed. Job-shop involves intermittent processing, high flexibility, skilled workers, relatively
large work-in-process inventories and general-purpose machinery. An example is a tool and
die shop that is able to produce a wide variety of tools.
b. Batch: Batch processing is used when a moderate volume of goods and services is demanded.
It is designed to handle a moderate variety in products. The processing is intermittent. The
flexibility of the process to produce a variety of goods, the skill of the workers, amount of
work-in-process inventories are all less than job shop. Typical examples of batch processing
are paint manufacturing and clothes making.
c. Repetitive: This type of a process involves higher volumes of more standardized goods or
services. The flexibility of the process to produce a variety of goods, the skill of the workers,
amount of work-in-process inventories are all less than batch process. Typical examples for
this type of process include appliances and automobiles assembling.
d. Continuous: This type of a process involves very high volume of highly standardized goods
or services. These systems have no flexibility in output or equipment. Workers are generally
low skilled and there is no work-in-process inventory. The machines are dedicated to perform
specified tasks. Typical examples include petroleum products, steel and sugar processing.
e. Project: Projects are designed to be used with non-routine, unusual tasks or activities. These
activities are generally not repeated. Equipment flexibility, level of worker skills and workin-process inventory can range from very low to very high. Examples include construction of
a dam or a bridge, conversion of the production system from job-shop to cellular
manufacturing, installing and implementing a new inventory and bar coding system.
Advantages: Highly uniform output, boredom and fatigue are not factors, machines don't go out
on strike, etc.
Disadvantages: Rigidity, expensive, setting up is hard.
Computerized numerically controlled (CNC) machines are programmed to follow a set of
processing instructions. Robots have movable arms that enable them to handle a wide variety of
tasks such as welding, loading and unloading machines, painting, and testing.
Flexible manufacturing systems (FMS) are groups of CNC machines that have a supervisory
computer, automatic material handling, and automatic processing. Systems usually range from 3
machines to a dozen. They are designed to handle a variety of processing requirements (similar to
intermittent systems) with some of the benefits of automation.
Computer-integrated manufacturing (CIM) is a system for linking manufacturing activities
through an integrated computer. These include engineering design, flexible manufacturing
systems, and production planning and control.
Operations Management, 2/ce
5.
6.
7.
8.
9.
10.
11.
(See question #4 above for description.) FMS is usually used as an automated manufacturing cell
working on a family of similar parts.
Process selection decisions often include aspects that require highly technical knowledge. Many
managers do not possess such expertise. However, if those decisions are delegated to engineers or
others who do have the expertise, there is the danger that managerial issues will suffer. The
solution is for managers to increase their knowledge of technological advances. In the meantime,
managers must be prepared to ask questions and impress upon technical experts their goals and
objectives.
A process flowchart or diagram is a graphical representation of steps of process (operations,
delays, etc.)
The trade-offs between product layout and process layout include the following:
a. Process layout has more equipment flexibility.
b. Process layout generally has higher skilled workers.
c. Product layout involves higher volume manufacturing.
d. Process layout benefits from high flexibility to be able to produce a variety of products,
while product layout benefits from large volume manufacturing at low cost.
e. The major goal of process layout is to minimize the transportation and material handling
costs while the primary objective of the product layout is to minimize idle time and maximize
efficiency of the process.
f. The utilization of process layout generally results in higher levels of work-in-process
inventory than the product layout.
g. For a product layout, the flow of work is straight, while for process layout, the flow of work
is mixed depending on the product produced.
h. There is more dependency between workstations for product layout than for a process layout.
i. The preventive maintenance and machine reliability are more important in a product layout
than process layout because equipment breakdown may involve shutting down a work station
which may in turn result in shutting down downstream work stations.
j. Routing and scheduling is much less complicated for processes with product layout than
processes with process layout.
- Estimate space requirements. Is there enough space available?
- Determine the roads and rail access to the site.
- Draw a process flowchart and superimpose it on the map of shop floor, starting from receiving
and ending in shipping.
- Allow space for material handling.
- Rearragne the layout seeking feedback from affected workers.
- Mark out line of machines on the shop floor.
Product layouts are generally characterized by specialized labour and equipment designed for
continuous processing. The layout is often arranged on the basis of processing sequence. Process
layouts are more general in nature, in terms of labour, processing equipment and material
handling equipment. Process layouts often feature machine groups or departments. Items
processed in process layouts tend to follow differing paths through the system.
The main advantages of product layouts include:
a. A potentially high rate of output.
b. Low unit costs.
c. Low training costs and wide span of supervision due to specialization.
Instructor’s Manual, Chapter 6
79
12.
13.
14.
15.
80
d. Low unit cost for material handling.
e. High utilization of labour and equipment.
f. Routing and scheduling are built into the design.
g. Accounting, purchasing and inventory control are fairly routine.
The main disadvantages of product layouts include:
a. Specialization can mean dull, repetitive jobs with little opportunity for personal satisfaction
or creativity.
b. Workers may have little interest in maintaining equipment or in the quality of output.
c. The system is not particularly adaptable to changes in process design or changes in the
volume of output.
d. The system is highly susceptible to shutdowns caused by equipment failure or excessive
absenteeism.
e. Preventive maintenance costs and the capacity for quick repairs are necessary to ensure high
utilization.
f. Incentive plans tied to individual output are impractical.
The main advantages of process layouts are:
a. They can handle a variety of processing requirements.
b. The system is less vulnerable to equipment failures than product layouts.
c. The general purpose equipment used is often less costly than the specialized equipment used
in product layouts. It is also usually easier and less costly to maintain and repair.
d. Individual incentive systems are possible.
The main disadvantages of process layouts are:
a. In-process inventory costs can be high (manufacturing).
b. Routing and scheduling must be done for each new job.
c. Equipment utilization rates are usually low.
d. Material handling is slower, less efficient, and more costly per unit than with a product
layout.
e. There is often a lower span of supervision compared to a product layout.
f. Unit costs tend to be higher than comparable output produced with a product layout.
g. Accounting, inventory control and purchasing are generally more involved than with a
product layout.
The main goal of line balancing is to achieve a set of task groupings at work stations in the line
that have equal time requirements in order to get a high utilization of labour and equipment.
Unbalanced lines have bottlenecks at some work stations and idle time at others. The resulting
output is lower than it would be if the line were balanced.
Routing and scheduling are continual problems in a process layout because a variety of jobs pass
through the system, and they tend to differ in terms of routing and schedule requirements. In
contrast, product layouts typically handle items with little or no variety—all have the same or
similar routing and scheduling requirements.
With a product layout, equipment breakdown has serious implications because the separate pieces
of equipment are closely tied together. If one piece of equipment fails, the line will quickly come
to a halt. Consequently, preventive maintenance to reduce the failure rate is advisable. In contrast,
a process layout often contains duplicate equipment so that if one particular piece of equipment
fails, the work can usually be shifted to another piece of equipment. Consequently, there is less
need for preventive maintenance, and less need for repair of equipment when it does break down.
Operations Management, 2/ce
16.
17.
18.
19.
20.
21.
22.
23.
Moreover, process layouts utilize more skilled workers who tend to take better care of the
equipment than their lower skilled counterparts in a product layout system.
Job processing sequence usually determines the arrangement of equipment in a product layout. In
a process layout, job processing sequences vary, so there is much less influence on equipment
arrangement. Because of differences in job requirements, sequencing is a continual task in a
process layout.
The subway system is essentially a fixed-path arrangement—a product layout. Its advantages are
often low operating cost, more efficient handling, and low cost per unit moved. On the other
hand, a bus system is more flexible in terms of varying routes. This can be desirable if there are
shifts in where potential riders are coming from and going to. For example, a new bus route could
easily be established to service a new shopping area, a new apartment complex, or a large
industrial facility. Other considerations are initial cost (high for subway and relatively low for
bus), severity of difficulties that would arise from a breakdown (high for subway, low for bus),
the possibility of alternative uses (none for subway, private groups, etc., for bus during off times),
and possible disruptions caused by weather (higher risk for bus than subway—e.g., snowstorms
stall highway traffic).
Fixed-path material handling equipment in supermarkets includes the belts at the checkouts which
move items up to the cashier, the roller conveyors which transport boxes of groceries outside to
pickup areas, conveyors in the meat department to move carcasses from storage to cutting tables,
roller conveyors to off-load goods from trucks and move them to storage. Variable-path material
handling equipment includes grocery carts, "trucks" and palletjacks used to transport goods from
storage to display shelves, and movable racks to transport baked goods from ovens or from
deliveries to the bakery counter.
Heuristic approaches are rules designed to guide decision makers to satisfactory decisions by
reducing the number of alternatives that must be considered. They do not necessarily yield
optimal solutions. They are usually employed when there is a problem involving an exceedingly
large number of potential solutions.
Nonmanufacturing environments do not usually lend themselves to product layouts because they
tend to involve more processing variety than many manufacturing environments. One exception
is a cafeteria.
The original car was one of a large number of similar cars produced on an assembly line, which
was set up to speed the flow of work. That is, inventories of parts were on hand, specialized
machinery, workers and material handling equipment were arranged specifically for the job. As
well, parts and components are made in large batches reducing the unit cost. As a result of this,
the unit cost of the car was relatively low. In contrast, constructing a car from “scratch” is
essentially a cross between job shop and a project, with none of the economies of mass
production. A list of the parts must be assembled. Some might be available locally, but others
would have to be shipped individually from suppliers. The parts would have to be held until all
were on hand. Workers would not be highly familiar with this particular car. Consequently, the
work would progress at a fairly slow rate, and probably with a certain amount of back-tracking.
Obviously, construction of a replacement would be considerably more costly than the initial car.
Layout can lead to high productivity if it contributes to a smooth flow of work with high
utilization of labour and equipment. This requires careful consideration of work requirements to
determine what will be needed and a certain amount of effort to obtain an optimal (or
satisfactory) layout. A poor layout will hinder productivity with bottlenecks, lower utilization of
labour and equipment than is necessary, and require more handling or movement between work
stations than is necessary (particularly in process layouts).
In cellular manufacturing, machines are grouped into a cell. The basis for grouping can be
operations needed to process a group of similar items or part families. Advantages of such
Instructor’s Manual, Chapter 6
81
24.
25.
26.
systems include relatively short throughput time, reduced material handling, less work-in-process
inventory, and reduced setup time.
Group technology involves selecting items that have similar design or processing requirements
and grouping them into part families for cellular manufacturing. It also includes a coding system
for items.
Although, we treated the task times as fixed in balancing assembly lines, it is more realistic to
assume variable task times whenever humans are involved. The lower the level of automation, the
higher the variability of tasks. If the assembly line consists of tasks with variable times, it will be
more difficult to balance the line. In order to deal with variability of task times, we can require a
minimum amount of idle time to be available at each workstation. As the variability of task times
increase we can increase the minimum idle time available at each workstation. In addition
workstation idle time can also be used for slower or less experienced workers who take longer
than normal to complete a task.
Factors such as opportunity to use available, less expensive equipment, familiarity with machines
and equipment, expertise of workers, space minitations, choice of alternate materials, and
strategic implications of this process.
Memo Writing Exercises
1.
In most cases it is not feasible to perfectly balance a production line. First, there are
technological constraints dealing with precedence and incompatibility issues. In other words,
certain tasks have to be performed before others (precedence) and two tasks may not be
performed at the same station due to their incompatibility (space and nature of operation
considerations). Secondly, there are output constraints. Since most task times vary, output
constraint determines whether an otherwise eligible task will fit at a work station because sum of
the task times assigned to a station can not exceed the cycle time. As a result of both
technological and output constraints, it is extremely difficult to achieve a perfectly balanced
production line. The larger the number of tasks, the more difficult to achieve perfect balance.
2.
Producing two products on the same assembly line allows the company to utilize the same
workstations to produce the common parts and available to them. This results in reduced labour
and capital costs. If one of the products is new, the company can shorten the period of time from
design to actual production, and reduce the cost of manufacturing in the long run.
3.
Fixed automation is utilized in a continuous flow/mass production environment. It enables the
firm to manufacture a single or a few products at high volume and low cost. However, it is not
flexible enough to produce a variety of parts and it is very costly to make changes to the process.
Flexible automation is utilized in a batch environment, where a wide variety of products can be
produced without significant changeover (setup) time/cost. Flexible machinery is not designed for
high volume (mass) production.
82
Operations Management, 2/ce
Solutions
1.
OT = 450 minutes
a. Minimum cycle time = length of longest task, which is 2.4 minutes.
Maximum cycle time =  task times = 18 minutes.
b. Range of output:
450
Maximum: @ 2.4 min.:
= 187.5 units
2.4
450
Minimum: @ 18 min.:
= 25 units
18
c.
187.5(18)
D x t
N=
=
= 7.5, Which rounds to 8
OT
450
d.
OT
450
Output =
Solving for CT, CT =
= 3.6 minutes per cycle.
CT
125
e. Output:
OT
450
(1) CT = 9 min.:
=
= 50 units
CT
9
450
(2) CT = 15 min.:
= 30 units
15
[2, 1.6]
2.
0.6
[7, 6]
1.4
[No. of followers, positional weight]
c
[1, 1]
0.5
[6, 4.6]
0.5
[2, 2.2]
0.7
f
[0, 15]
0.5
b
d
[1, 1.5]
1.0
h
[2, 2.3]
0.8
g
a
e
Desired output = 33.33 units per hour
Operating time = 60 minutes per hour
CT =
Operating time
60 minutes per hr.
=
= 1.80 minutes per unit
Desired output
33.33 units per hr.
Instructor’s Manual, Chapter 6
83
Solutions (continued)
a.
Station
1
2
3
4
Time left
1.8
0.4
1.8
1.3
0.5
1.8
1.1
0.5
1.8
0.8
0.3
b. Efficiency = 1 –
3.
Eligible
a
b
b
c, d, e
c, d
c, d
c, g
g, f
g
h
Will fit
a
-b
c, d, e
-c, d
c, g
f
g
h
Assign
(time)
a (1.4)
Idle
0.4
b (0.5)
e (0.8)
0.5
d (0.7)
c (0.6)
f (0.5)
g (1.0)
h (0.5)
--
0.3
1.2
Total idle time
=1–
CT x no. of stations
[4, 23]
3
1.2
= 83.3%
7.2
[3, 18]
4
[3, 20]
2
a
b
c
[3, 25]
7
[2, 18]
4
[1, 14]
9
[0, 5]
5
d
e
h
i
[3, 24]
6
[4, 29]
5
g
f
Desired output = 4
Operating time = 56 minutes
CT =
84
Operating time
Desired output
=
56 minutes per hr.
4 units per hr.
= 14 minutes per unit
Operations Management, 2/ce
Solutions (continued)
a.
Station
1
2
3
4
Time left
14
9
6
14
7
5
1
14
10
1
14
9
Eligible
A, d, f
A, d, g
D, g, b
D, b
B, e
E, c
C
C
H
I
I
Time left
14
9
2
14
8
5
3
14
10
6
14
5
Eligible
A, d, f
A, d, g
a, g
A, g
A, e
E, b
E, c
E, c
C
H
H
I
Will fit
A, d, f
A, d, g
G, b
D, b
B, e
E, c
-C
H
-I
2
3
4
Idle
0
1
C (4)
H (9)
1
I (5)
9
11
b.
Station
1
Assign
(time)
F (5)
A (3)
G (6)
D (7)
B (2)
E (4)
Will fit
A, d, f
A, d, g
Assign
(time)
F (5)
D (7)
Idle
2
A, g
A, e
E, b
-E, c
C
-H
I
G (6)
A (3)
B (2)
-E (4)
C (4)
3
6
4 (9)
I (5)
0
11
idle time
45

 80.36%
CT x no. of stations 56
Total idle time
11
11
 80.4%
CT x no. of stations
56
c. Efficiency =
4.
c
a.1.
a
d
b
e
Instructor’s Manual, Chapter 6
f
h
g
85
Solutions (continued)
2. Mininum Ct = 1.3 minutes
Task
a
b
c
d
e
f
g
h
Station
I
II
III
IV
3.
4.
86
Following tasks
4
3
3
2
3
2
1
0
Will
Eligible
fit
Time
remaining
1.3
1.1
.7
.4
.3
1.3
.5
1.3
a, c, e
b, c, e
c, e
e, d
d, f
f
g
h
Idle percent:
Output:
OT
CT
a, c,
b,ec,
c,e e
e
d, f
f
g
h
Assign
Time
a
b
c
e
d
.2
.4
.3
1
1.3
.8
.3
1.2
g
h
Idle
time
0.3
0.0
0.2
0.1
0.6
.6
(idle time)
=
= 11.54 percent
N x CT
4(1.3)
420 min./day
=
= 323.1 units/day
1.3 min./cycle
Operations Management, 2/ce
Solutions (continued)
Total time
4.6
=
= 2.3 minutes.
N
2
Assign a, b, c, d, and e to station 1: 2.3 minutes
Assign f, g, and h to station 2: 2.3 minutes
2. No idle time.
OT
420
3. Output =
=
= 182.6 units per day.
CT
2.3
b. 1.
5.
Total time = 4.6 min., CT =
a.
.2 [4]
a
1.2
.2 [2]
c
.4 [3]
b
[1]
f
1.0
[0]
g
1.2
.4
d
b. CT =
c. N =
OT
=
output
t
=
CT
Time
Left
d. Station
1
3
4
e. Idle percent 
6.
a.
[2]
[1]
480 min/day
= 2 minutes
240 units/day
4.6
= 2.3 (round to 3) stations
2.0
Assign
Eligible Will Fit (time)
2
1.8
1.4
1.0
.8
2
.8
2
.8
2
1
2
e
A, d
D, b
D, c
C, e
E, f
E, f
F
F
G
g
A, d
D, b
D, c
C
-E, f
E (1.2)
F
F (1.2)
g
G (1)
Idle
time
A (.2)
B (.4)
D (.4)
C (.2)
.8
.8
.8
1.0
3.4
3.4
3.4

 42.5%
(4)(2) 8.0
Task times
0.1
0.2
0.9
0.6
a
b
c
d
(3.9)
(3.8)
(3.6)
(2.7)
Positional weights in
parentheses.
Instructor’s Manual, Chapter 6
0.1
0.2
0.4
0.1
0.2
0.7
e
f
g
h
i
j
(2.2)
(2.1)
(1.9)
(1.5)
(1.4)
(1.2)
(0.5)
k
0.3
(0.2)
l
0.2
87
Solutions (continued)
b.
Time
Station Remaining Eligible
1
1.5
a, e
1.4
e, b
1.2
e, c
.3
e, d
.2
d
2
1.5
d
.9
f
.7
g
.3
h
.2
i
3
1.5
j
.8
k
.5
l
c.
7.
% idle time =
d
f
g
h
i
j
k
l
d (.6)
f (.2)
g (.4)
h (.1)
i (.2)
j (.7)
k (.3)
l (.2)
Idle Time
2
.5
x 100 = 11.1%
3 (1.5)
a.
0
.3
.5
12
G
45
A
11
B
9
C
50
26
D
b. CT
=
c. N
=
88
Will Fit
a, e
e, b
e, c
e
Assign
(task)
a (.1)
b (.2)
c (.9)
e (.1)
OT
=
D
t
CT
E
7(60)
500
=
10
H
9
I
10
J
11
F
= .84 minutes = 50.4 seconds
193
50.4
= 3.83 or 4 stations
Operations Management, 2/ce
Solutions (continued)
d.
Task
Number of followers
A
6
B
5
C
4
D
4
E
3
F
2
G
2
H
2
I
1
J
0
*Positional weight
*PW
106
61
50
106
56
30
31
29
19
10
CT = 50 seconds
Station
1
2
3
4
5
e.
I
Time Left
50
5
50
50
39
13
4
50
38
27
17
8
50
40
Eligible
A, D
D, B
D, B
B, E
E, C
C, F
F, G, H
F, G, H
F, H
H
I
J
J
Will Fit
A, D
-D, B
B, E
E, C
C, F
-F, G, H
F, H
H
I
-J
Assign Task
(time)
A (45)
D( 50)
B (11)
E (26)
C (9)
Idle
5
0
4
G (12)
F (11)
H (10)
I (9)
8
J (10)
40
57
57
 22.8%
(50)(5)
Instructor’s Manual, Chapter 6
89
Solutions (continued)
8.
.5
a
1.4
b
1.2
c
.5
e
.7
1.0
f
d
b. CT =
c.
Tasks
a
b
c
d
e
f
g
h
i
j
k
m
Station
1
2
3
4
5
c.
90
.4
g
.3
h
.8
j
.3
.9
k
m
.5
i
200
= 2.0 minutes
400
Positional Number of
Weight Followers
8.5
11
4.6
6
4.4
6
4.2
5
3.2
5
3.5
4
1.9
3
1.5
2
2.5
3
2.0
2
1.2
1
.3
0
Time Left
2.0
1.5
.1
2.0
.8
.1
2.0
1.5
.5
2.0
1.6
.8
.5
2.0
1.1
.8
Balance delay:
Eligible
a
b, c, d
c, d
c, d
d, e
e, f
e, f
f, g
g, i
g, j
j, h
h
k
k
m
Will Fit
a
b, c, d
-c, d
d, e
-e, f
f, g
g, i
g, j
j, h
h
-k
m
Assign (time)
a (.5)
b (1.4)
Idle
.1
c (1.2)
d (.7)
.1
e (.5)
f (1.0)
i (.5)
g (.4)
j (.8)
h (.3)
0
.5
k (.9)
m (.3)
.8
1.5
1.5
= 15%
5(2)
Operations Management, 2/ce
Solutions (continued)
10.
9.
1
4
1
2
5
4
2
6
5
3
1
6
2
A
X
o
11.
1
II
# of A neighbours
2
I
1
1
3
IIII
4
II
5
IIII
8
3
4
5
3
6
5
4
7
II
4
8
IIII
o
o
A
o
o
o
o
o
o
5
A
6
8
6
II
o
o
3
7
2
2
3

3
3

4
3
5
8
7
2
5
1
6
1
6
1
6
x:
1
2
4
7
12.
1
2
# of A neighbours
4
3

7
4

8
3

5
1
2
1
2
1
7
5
3
3
2
1
3
2
7
7
8
4
8
8
3
2
4
8
5
1
7
6
7
4
x:
5
1
6
3
2
8
4
6
8
4
7
13.
# of A neighbours
1
III

2
3
III II

4
II

3
(a)
8
4
5
8
II
9
III

3
(d)
2
9
8
Instructor’s Manual, Chapter 6
1
2
6
8
7
4
5
(e)
1
7
7
8
7
IIII I

(c)
1
2
6
II
3
(b)
1
9
5
III

9
7
5
4
2
4
1
4
8
2
6
6
3
5
7
9
5
9
91
Solutions (continued)
3
1
8
9
7
4
5
2
6
14.
3
5
8
6
9
One approach is to first combine the from-to number of trips into a single ‘between’ table. That
is, add the trips from I to j to the number of trips from j to i.
1
1
2
2
3
4
10
20
80
40
90
3
55
4
0
Then rank the ‘between’ trips between departments:
1.
2.
3.
4.
2, 4:
1, 4:
3, 4:
2, 3:
90
80
55
40
Next, rank the locations from closest pair down:
A, B:
B, C:
B, D:
C, D:
A, D:
A, F:
40 metres
40 metres
50 metres
60 metres
70 metres
80 metres
2?
4?
A
Finally, assign the pair with highest number of trips between them as close as
possible on the floor plan. If there is a tie, use a question mark in front of the
assignment, but mark alternate locations. In this case, 2,4 have the highest
trip, and they can be in A,B or B,C.
D
The next high number of trips are for department 1,4. Given that 2 and 5 can only
occupy either the pair of locations A,B or B,C, it follows that department 1 should
occupy either A or C. Therefore, department 3 should be assigned to D. The 4th
highest number of trips is between 2 and 3. The next closest locations are C and D.
Therefore, 2 should be located in C:
92
2?
1?
C
4
B
1
4
2
3
Operations Management, 2/ce
Solutions (continued)
15.
Pair of
departments
1, 2
1, 3
1, 4
1, 5
1, 6
1, 7
1, 8
2, 3
2, 4
2, 5
2, 6
2, 7
2, 8
3, 4
3, 5
3, 6
3, 7
3, 8
4, 5
4, 6
4, 7
4, 8
5, 6
5, 7
5, 8
6, 7
6, 8
7, 8
No. of Trips / day
(Two ways)
10
5
90
370
135
125
0
360
120
40
115
45
120
350
110
40
20
200
190
70
50
190
10
40
10
50
20
20
Rank
1
7
8
2
9
11
10
3
12
4
5
6
Assign by rank:
1
5?
5?
1
3
5?
5?
3
1
5?
1
5?
5?
2?
4?
5?
2?
4?
3
8
2?
4?
3
2?
4?
Instructor’s Manual, Chapter 6
1
5?
5?
1
4
3
5?
6?
8
2
5?
6?
1
5?
6?
4
3
5?
6?
4
8
2
7
8
1
5
3
6
4
3
2
7
8
2
93
Solutions (continued)
16.
The distances are ranked as:
A, B
All other neighbour pairs
All pairs next to neighbours
..
.
20 ft.
40 ft.
60 ft.
..
.
Assign 3,5 as close as possible. The next highest number of trips is between 2 and 6. There are
many choices: C, D, E, F.
2?
3? 5?
6?
6?
2?
3? 5?
2?
4?
6?
6?
The next highest number of trips is between 1 and 4. So:
5?
3?
3?
5?
6?
2? 2?
6? 4? 1?
2? 6?
1?
4?
6? 2?
1? 4?
4? 1?
The next highest number of trips is between 4 and 6. This narrows the choices to:
5?
3?
3?
2? 6?
1?
4?
2?
5?
6?
4?
1?
The next highest number of trips is 1 and 5. This fixes all departments:
3
2
5
17.
94
1
4
6
Because the opposite trip needs to go around the hall, complementing it, and because the distance
of going around the hall is the same, it follows that a reasonable approach ill use the absolute
value of difference between loads in the opposite direction.
Operations Management, 2/ce
1
1
(Difference
in loads)
2
40
2
3
4
3
49
4
14
5
17
6
1
7
19
8
8
9
1
10
25
33
14
23
5
14
6
8
24
2
6
6
50
10
11
34
35
14
6
18
21
9
20
4
5
17
5
13
44
49
15
12
27
40
41
15
5
6
7
8
9
17
10
Now rank these:
1,7
1,3
6,8
8,9
1,2
7,10
6,9
4,5
3,10
2,3
7,9
1,10
2,10
2,5
4,9
5,6
..
.
50
49
44
41
40
40
39
35
34
33
27
25
24
23
21
20
..
.
Instructor’s Manual, Chapter 6
3? 7?
1
7? 3?
6? 9?
2
8
6? 9?
95
Solutions (continued)
-
7
Assign 3 & 7 close to 1.
Assign 6 & 9 close to 8.
Assign 10 close to 7:
10 goes in C, which fixes
7 to B, and 3 to J.
1
3
10
6? 9?
2
8
-
Assign 4 & 5 in G & H.
Assign 7 & 9 close together.
This fixes 9 to D, and 6 to F.
Assign 2 & 5 close together.
This fixes 5 to H and 4 to G.
5? 4?
6? 9?
4? 5?
7
1
3
10
9
2
8
5
6
96
4
Operations Management, 2/ce
Solutions (continued)
18.
Station
1
2
Time Left
50
50
5
50
24
13
2
50
41
29
19
10
3
4
19.
Eligible
A, D
A, E
E, B
E, B
B, F
F, C
C
C
G, H
H
I
J
Will fit
A, D
A, E
-E, B
B, F
F, C
-C
G,H
H
I
J
Assign Task
(time)
D (50)
A (45)
Idle Time
0
5
E (26)
B (11)
F (11)
2
C (9)
G (12)
H (10)
I (9)
J (10)
0
7
a.
Customer
arrives
Wait
Use a “float”
as a teller
Loss of
Goodwill
All
Servers
Busy
Possible
Failure
Specifies
need
Teller asks coworkers / manager
Teller
knows how to
satisfy
need?
Possible
Failure
Resulting delays
loss of Goodwill
Customer receives
receipt, etc. & leaves
Instructor’s Manual, Chapter 6
97
Solutions (continued)
b.
1. Customer
arrives
1.1
Customer
arrives
1.1
2. Contact
with teller
1.2
Customer
waits
1.2
2.1
3. Customer
leaves
2.1
Customer
states needs
2.2
Teller performs
necessary actions
2.2.1 Teller
identifies type of
transaction needed
3.1
Customer
receives
receipt, etc.
2.2.2 Teller follows
procedure for the
identified transaction
3.1
3.2
Customer
leaves
3.2
20.
Customer
arrives
Hostess greets
& determines
table
Hostess
seats
customer
Waiter greets, gives
menu, & takes
beverage order
Kitchen
produces
order
Waiter
returns
with food
Waiter checks back
after 5 min. to see if
food is good
Waiter returns
with beverage &
takes food order
Waiter checks back after
30 min. to take plates;
takes dessert order
98
Waiter
returns with
desserts
Waiter returns
with bill after
10 min.
Bartender
produces
order
Customer
pays and
leaves
Operations Management, 2/ce
Reading: Jubilee Ford
Answers to Questions:
1.
Customer
calls &
books appt.
Car
Car brought in in
the morning of
appointment day
Service advisor obtains customer
personal info and customer need. If
there is a problem to be diagnosed, this
info is also written on work order
Customer signs
work order
authorization
and leaves
Work Order
Car
Work
order
2.
3.
Car
waits
for
service.
Tower dispatcher
assigns and
sequences the job
Technician
does the work
and reports
back to
dispatcher;
comments
written on
work order.
Car
Waits
outside
Work
order
Service advisor
calls customer
that car is ready
Customer
comes, payes,
and takes the
car.
Process type for service department is job shop: many types of customized service by various
technicians.
Dispatcher performs the job scheduling function (see Chapter 17). It is important because its
efficiency directly affects technician utilization and customer service.
Operations Tour: Redpath Sugar
Answer to questions
1.
Capacity of shed is 65,000 tonnes. The capacity of production is 100 tonnes/hour, working 24
hours a day, 5 days a week. Therefore, raw sugar is enough for:
= 65,000 / (100*24*5) = 5.4 weeks.
Assuming that a full ship arrives when the shed is half full and just before the St. Lawrence
Seaway freeze, there may be enough raw sugar for 2 months, which is not enough.
Instructor’s Manual, Chapter 6
99
2.
Water
Docked
ship
Crushed
sugar cane
Mix
Water
Centrifuge
Shed
Sugar
crystals
Charcoal
Filters
(cistern)
Hot water
Steam
Sweetland
Press
(cloth filters)
Melter
Mix
Strainer
Water
Evaporate
Vacuum Pan
(boil)
(re-crystallization)
Solids
(impurities)
Calcium
carbonate
Water
Tumble
Dryer
Centrifuge
Hot air
Screens
(sizing)
Packaging
Store
Distribute
Solid particles
Overfill
silos
Reading: Tour De Force
Answer to questions
1.
The Viper/Prowler assembly plant is much smaller than typical automobile assembly plants. The
plant covers 392,000 square feet of space as opposed to other typical auto assembly plants that
cover from 2 million square feet to 5 million square feet of space.
The production capacity of the Viper plant is much less than a typical automobile assembly line.
The Viper plant's daily production capacity is 13 Vipers and 20 Prowlers compared to large
automobile assembly plants that can manufacture 1000 vehicles per day.
While most large automobile plants require 2000 or more workers, the Viper plant employs only
260 employees.
The Viper plant employs skilled "craftsman" workers. Typical auto assembly plants use workers
to do repetitive work with little skill required.
There are no robots or automation in the Viper plant while most auto assembly plants have high
levels of automation.
100
Operations Management, 2/ce
2.
The Viper plant uses early 20th century manual assembly techniques on two manual, parallel,
relatively short (12 work stations and 720 feet long) assembly lines with generous idle time built
in. Typical assembly lines usually involve the use of robots, large number of workstations and
very little idle time.
The reasons for not having robots or other high level automation include the following:
Chrysler Corporation wants to portray a high quality image of two handcrafted automobile
models that is generally more expensive and appealing to high-income individuals. The personal
attention to the customers is part of the marketing package associated with both products.
Operations Tour: Hi-Bek Precision Spring Co. Ltd.
Answers to questions
1.
2.
3.
Job shop, because every job is different and production is based on customer order of their
specific design. However, the process flows are rather similar for all the jobs..
Because Hi-Bek carries inventories of various types and gauges of raw material (wires), and a
large amount of WIP in order to efficiently schedule and use its equipment and workers.
Yes, the layout groups various machines of the same type together. Most jobs follow the
sequences shown on the layout below. As it can be observed, the movement of material is
usually minimized (especially if WIP is stored for a while, given that inventory is kept in the
middle). However, for Job B, requiring grinding and then finishing, there is excessive material
handling. The location of grinding is chosen so that the dust from it is contained in the corner of
the shop. Perhaps finishing operations can be moved closer to the shipping gates in order to
reduce material handling and throughput time.
Job
B
Instructor’s Manual, Chapter 6
Job
A
Job
C
101