PRODUCT AND SERVICE DESIGN

CHPTER THREE
DESIGN OF THE OPERATION SYSTEM
PRODUCT AND SERVICE
DESIGN

 product design is the process of deciding on
the unique characteristics and features of the
company’s product.

PRODUCT AND SERVICE DESIGN
 What does Product and service
design do?
 The various activities and
responsibilities of Product and service
design include
 Translate the customer wants and
needs into product and service
requirements
 Refine existing products and services
(marketing)

PRODUCT ANDSERVICE DESIGN
 Develop new products and/or services(
marketing and operation)
 Formulate quality goals ( marketing and
operation)
 Formulate cost targets (accounting ,finance
and operations)
 Construct and test prototype ( marketing ,
operations, engineering)

REASONS FOR PRODUCT AND SERVICE DESIGNOR REDESIGN
 Product and service design has typically had
strategic implications for the success and
prosperity of an organization .
 Organization become involved in Product
and service design or redesign for a variety
of reasons
 The main forces that initiate design or
redesign are marketing opportunities and
threats

REASONS FOR PRODUCT AND SERVICE DESIGNOR REDESIGN
 The factors that give rise to market
opportunities and threats can be one or more
changes

VALUE ANALYSIS
 Refers to an examination of the function of
parts and materials in an effort to reduce cost
and improve performance of a product.

OBJECTIVES OF PRODUCT ANDSERVICE DESIGN
 The main focus of Product and service
design is customers satisfaction.
 Hence ,it is essential for designers to
understand what the customer wants and
design with that in mind.
 Secondary focuses in Product and service
design relate to function, cost, potential
profit, quality, appearance, forecasted value

 Ease of production, ease of assembly and
ease of maintenance or service.
 In general ,design ,operations and marketing
must work closely together ,keeping each
other informed and taking in to account the
wants and needs of the customer.

 In addition , legal, environmental and ethical
considerations can influence the design
function.

OTHER ISSUES IN PRODUCT AND SERVICE
DESIGN
 Aside from legal, environmental and ethical
consideration , designers must also take into
account
 Products or services life cycles
 How much standardization to incorporated
 Product or service reliability

LIFE CYCLES
 Many new product and service go though a
life cycles in terms of demand.
 When an item is introduced, it may be
treated as a curiosity
 Demand is generally low because potential
buyers are not yet familiar with the item
 Many potential buyers recognize that all of
the bugs have probably not been worked out

LIFE CYCLES
 And that the price drop after the introductory
period
 Capacity and processing are design for low
volume
 With the passage of time, design
improvements usually create a more
reliable and less costly output.
 Demand then grows for these reasons,

LIFE CYCLES
 And because of increasing awareness of
the product or service
 High volume will involve different methods
and contribute to low costs.
 At the next stage in the life cycle, product or
service reaches maturity: there are few, if
any, design changes and demand levels off

LIFE CYCLES
 Eventually ,the markets becomes saturated,
which leads to a decline in demand

STANDARDIZATION
 Standardization is
 Extent to which there is absence of variety in
a product, services or process
 Standardized products are made in large
quantities of identical items
 Standardization carries a number of
important benefits as well as certain
disadvantage

STANDARDIZATION
 Standardized products are immediately
available to customers
 Standardized products mean
interchangeable parts, which greatly lower
the cost of production higher
 While increase productivity and making
replacement or repair relatively easy
compared with that of customized
 Design costs are generally lower

STANDARDIZATION
 Another benefit of Standardization is
reduced time and cost to train employees
and reduced time to design jobs.
 Lack of Standardization is at times leads to
serious difficulties and competitive struggles
 High cost of design changes increases
resistance to improvements
 Decreased variety results in less consumer
appeal

DESIGNING FOR MASS
CUSTOMIZATION
 Companies like standardization because it
enables them to produce high volumes of
relatively low-cost products, albeit product
with little variety
 Customers, on the other hand,
 Typically prefer more variety , although they
like the low cost.

DESIGNING FOR MASS
CUSTOMIZATION
 The question for producers is to resolve
these issues without
1) Losing the benefits standardisation and
2) Incurring a host of problems that are often
linked to variety
These include increasing the resource needed
to achieve design variety

DESIGNING FOR MASS
CUSTOMIZATION
 increasing variety in production process,
which would add to the skills necessary to
produce the products
 Causing a decrease in productivity
 The answer , at least for some mass
customization, a strategy of producing
standardized goods or services, but
incorporating some degree of customization

PHASES IN PRODUCT DESIGN AND
DEVELOPMENT
 product design and development generally
proceeds in a series of phases
Idea generation
 Product development begins with Idea
generation
 Ideals can come from a variety sources.
They can be

IDEA GENERATION
 Supply chain based
 Competitor based
 Research based
 a Supply chain can be a rich source of ideas.
 Customers, suppliers, distributors,
employees, and maintenance and repair
personnel can provide valuable insight.

IDEA GENERATION
 One of the strongest motivators for new and
improved products or services is competitors'
product and services
 by studying a competitors' product and
services and how the competitor operates
 Pricing policies, return policies, warranties.
Location strategies etc an organization can
glean many ideals

IDEA GENERATION
 Some companies purchase a competitor’s
product and then carefully dismantle and
inspect it, searching for ways to improve their
own product, this is called reverse
engineering

FEASIBILITY ANALYSIS
 Feasibility analysis: entail
 marketing analysis(demand),
 economic analysis (development cost and
production cost ,profit potential and
 Technical analysis, capacity requirements
and availability and the skills needed

2 PRODUCT SPECIFICATIONS
 This involves detailed descriptions of what is
needed to meet(or exceed) customer wants
 3 process specifications
 Once Product specifications have been set,
attention turns to specifications for the
process that will be needed to produce the
product

CONT---
 Alternatives must be weighted in terms of
cost, Availability of resource, potential profit
and quality
 This involves collaboration between
accounting and operations
 4 prototype development.
 With Product and process specifications
complete,

CONT---
 One( or a few) units are made to see if
there are any problems With the Product
or process specifications
 5 Design review
 Make any necessary changes or abandon
 involves collaboration among marketing,
engineering, design, accounting and
operations

6 MARKET TEST
 A market test is used to determine the extent
of customer acceptance.
 If unsuccessful return to the Design review.
This phase is handled by marketing
 7 product introduction. Promote the product.
 This phase is handled by marketing
 8 follow-up evaluation

PROCESS SELECTION
 Technology
 Technology and Technological innovation
often have a major influence on business
organization
 Technological innovation refers to the
discovery and development of new or
improved product or services or process for
producing or providing them

CONT--
 Processes converts inputs into output
 Process selection refers to deciding on the
way production of goods or services will be
organized
 It has a major implication for capacity
planning, layout of facilities, equipments and
design of work systems

 Process selection occurs as a matter of
course when new products or services are
being planning.
 However ,it also occurs periodically due to
changes in product or equipments , as well
as competitive pressure

 Forecasting , product or service design and
technological consideration all influence
capacity planning and process selection.
 How an organization approaches process
selection is determined by the organization’s
process strategy. Key aspect include
 Capital intensity

Forecasting
Product and
Service Design
Technological
Change
Capacity
Planning
Process
Selection
Facilities and
Equipment
Layout
Work
Design
PROCESS SELECTION AND SYSTEM DESIGN

 Technology
 The application of scientific discoveries to the
development and improvement of product
and services and operations processes
 There are different kinds technology.
Operations management is primary
concerned with three technology

 1product and service technology is the
discoveries and development of new product
and services.
 This is done mainly by researchers and
engineers, who use the scientific approach to
develop new knowledge and translate that
into commercial application

 Process technology
 Information technology

PROCESS SELECTION
 The three questions bear on Process
selection
1) how much variety in products or services
will the system need to handle
2) what degree of the equipment flexibility will
be needed
3 what is the expected volume of out put
 Answers to these questions will serve as a
guide to selecting an appropriate process

PROCESS TYPES
 There are five basic process types
 Job shop
 Batch
 Repetitive
 Continuous and project

JOB SHOP
 Usually operated in small scale
 It is used when low volume
 High variety goods or services will be
needed
 Process is intermittent
 Work includes small jobs, each with
somewhat different processing requirements.

BATCH
 Batch processing is used when moderate
volume of goods or services is desired and
 It can handle a moderate variety in goods or
services
 The equipment need not be as flexible as in
job shop, but processing is still intermittent
 The skill level of work doesn’t need to be as
high as a job shop because there is less
variety

BATCH
 In the jobs being processed
 Examples of batch systems include bakeries,
which make bread, cakes in batches,
 movie theatres, which show movies to
groups(batches) of people and
 Airlines , which carry planeloads(batches) of
from airport to airport

BATCH
 Soft drinks
 Beer, magazines and books

REPETITIVE
 When higher volumes of more standardized
goods or services are needed, Repetitive
processing is used.
 The standardized output means only slight
flexibility of equipment is needed
 Skill of workers is generally low
 Examples of this types of system include
 Production line and assembly lines

CONTINUOUS
 When a higher volumes of non-discrete,
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
 Worker skill ranges

STRATEGIC CAPACITY PLANNING
 Capacity refers to upper limit or ceiling
on the load that an operating unit can
handle.
 The load might be in terms of the
number of physical units produced (e.g.-
, bicycles assembled) or the number of
services performed (e.g., computers
upgraded per hours)

 The goal of Strategic Capacity Planning
is to achieve a match between the long-
term supply capabilities of an
organization and the predicted level of
long-term demand.
 Organizations become involved in
Capacity Planning for various reasons.
 Among the chief reasons are:

REASONS FOR STRATEGIC CAPACITY
PLANNING
 Changes in demand
 Changes in technology
 Changes in environment and
 Perceived Threats or opportunities
A gap between current and desired
capacity will result in capacity that is out
of balance.

 Overcapacity cause operating costs
that are too high
 While under capacity causes
strained resources and possible
loss of customers.
 Some basic questions in Capacity
Planning are the following

QUESTIONS IN CAPACITY PLANNING
 What kind of capacity is needed?
 How much is needed?
 When is it needed?
 The question What kind of capacity is
needed depends on the products and
services that management intends to
produce or provide.

QUESTIONS IN CAPACITY PLANNING
 Forecasts are key inputs used to
answer questions How much is
needed and when is it needed

CAPACITY DECISIONS ARE STRATEGIC
 For a number of reasons, Capacity decisions
are among the most fundamental of all the
design decisions that managers must make
 Capacity decisions can be critical for an
organization
1) Capacity decisions have real impact on the
ability of the organization to meet future
demand for products or services

2) Capacity decisions affects operating costs
3) Capacity is usually a major determinant of
initial cost
4) Capacity decisions often involve long-term
commitment of resources and the fact that,
once they are implemented, those decisions
may be difficult or impossible to modify
without incurring major costs

5)Capacity decisions can affect
competitiveness
6)Capacity affects the ease of management

DEFINING AND MEASURING
CAPACITY
 No single measure of capacity will be
appropriate in every situation .rather ,the
measure of capacity must be tailored to the
situation.
 Commonly used measure of capacity are:
 Design capacity
 The maximum output rate or service capacity
an operation, process, or facility is designed
for

MEASURING CAPACITY
 Effective capacity
 Design capacity minus allowances such as
personal time, maintenance and scrap
 Design capacity is the maximum output rate
achieved under ideal conditions
 Effective capacity is usually less than design
capacity owing to realities of changing
product mix, the need for periodic
maintenance of

MEASURING CAPACITY
 Equipment ,lunch breaks, coffee breaks,
problems in scheduling and balancing
operations and similar circumstances.
 Actual output cannot exceed effective
capacity and is often less than because of
machine breakdowns, absenteeism,
shortages of materials and quality problems ,
as well as factors that are outside the control
of the operations managers

MEASURING CAPACITY
 These different measures of capacity are
useful in defining two measures of system
effectiveness:
 Efficiency and utilization
 Efficiency=actual output
 effective capacity
 Utilization=actual output
design capacity

MEASURING CAPACITY
 Both measures are expressed as
percentages
 Given the following information, compute the
Efficiency and the utilization of the vehicle
repair department
 Design capacity= 50 trucks per day
 Effective capacity= 40 trucks day
 Actual output =36 trucks per day


DETERMINANT OF EFFECTIVE
CAPACITY
 Facilities
 The design Facilities, including size and
provision for expansion, is key.
 Location factors, such tra.c,distance to
mkt,labour s. energey sources and room for
expansion
 Layout, env’ta factors
 Product and service factors
 Product or service design can have tremendous
influence on capacity.

DETERMINANT OF EFFECTIVE
CAPACITY
 Process factors
 The quantity capacity of a process is an
obvious determinant of capacity
 Eg. If the quality of output does not meet
standards , the rate of output will be slowed
by the need for inspection and rework
activities
 Productivity also affects capacity

 Process improvements that increase quality
and Productivity can result in increased
capacity
 Human factor
 Policy factor
 Management policy can affect capacity by
allowing or not allowing capacity options
such as over time, second or third shifts

STEPS IN THE CAPACITY PLANNING PROCESS
1. Estimate future capacity requirements
2. Evaluate existing capacity and facilities and
identify gaps
3. Identify alternatives for meeting
requirements
4. Conduct financial analyses of each
alternatives
5. Assess key qualitative issues for each
alternatives

6.Select the alternative to pursue that will be
best in the long term
7.Impement the selected alternative
8. Monitoring results

FORECASTING CAPACITY REQUIREMENTS
 Capacity planning decisions involve long –
term and short-term considerations
 involve long –term considerations relate to
overall level of capacity, such as facility size
 involve short-term considerations relate to
probable variations in capacity requirements
created by such things as seasonal, random
and irregular fluctuations in demand

 long –term capacity needs require
forecasting demand over a time horizon and
then converting those forecasts into capacity
requirements
 Some basic demand patterns that might to
identified by a forecast.
 In addition to basic patterns there are more
complex patterns, such as combinations of
cycles and trend

 When trends are identified, the fundamental
issues are
1. How long the trend might persist, because
few things last forever and
2. The slope of the trend
If cycles are identified, interest focus on
1) The approximate length of the cycles
2) The amplitude of the cycles(i.e deviation from
the average)

CALCULATING PROCESSING REQUIREMENTS
 A necessary piece of information is the
capacity requirements of products that will be
processed.
 To get this information, one must have
reasonable accurate demand forecasts for
each product and
 know the standard processing time per unit
for each product, the number of workdays
per year

 And the number of shifts that will be used .
 A department works one 8-hours shifts, 250
days a year, and has these figures for usage
of a machine that is currently being
considered.

product Annual
demand
Standard
processi
ng time
per
unit(hr)
Processi
ng time
needed(
Hr)
1 400 5 2,000
2 300 8 2,400
3 700 2 1,400
5,800

 Working one 8-hours shifts 250 days a year
provides an annual capacity of 8 *250=2,000
hours per year.
 We can see that three of these machines
would be needed to handle the required
volume:
 5800 hours = 2.9 machines
2000 hours/machine

THE CHALLENGES OF PLANNING SERVICE
CAPACITY
 It is important to note that capacity planning
for services can present special challenges
due to its nature of services
 Three very important factors in planning
services capacity are
1) The need to be near customers
2) The inability to store services
3) The degree of volatility of demand

MAKE OR BUY
 Once capacity have been determined, the
organization must be decided whether to
produce a good or provided a service itself,
or to outsource(buy) from another
organization.
 Many organizations buy parts or contract out
services, for a variety of reasons.
 Among those factors are
 1 available capacity

MAKE OR BUY
 2) Expertise. If a firm lacks the Expertise to
do a job satisfactorily, buying might be a
reasonable alternative
 3)quality considerations
 4) the nature of demand
 5) cost
 6) risk. Outsourcing may involve certain
risks. One is loss of control over operations.

MAKE OR BUY
 Another is the need to disclose proprietary
information

DEVELOPING CAPACITY ALTERNATIVES
 Aside from the general considerations about
the development of alternatives (i.e .,conduct
a reasonable search for possible
alternatives, take care not over-look
nonquantitative factors),there are other
things that can be done to enhance capacity
management.

1. Design flexibility in to the system
The long-term nature of many capacity
decisions and the risk inherent in long-term
forecasts suggest potential benefits from
reigning flexible systems.
2. Take stage of life cycle into account.
Capacity requirements are often closely linked
to the stage of life cycle that a service or
product is in

DEVELOPING CAPACITY
ALTERNATIVES
 At the introduction phase, it can be difficult to
determine both the size of the market and
the organization’s eventual share of that
market.
 Therefore, organizations should be careful in
making large and /or inflexible capacity
investments
 In the growth phase the overall market may
experience rapid growth.

 In the maturity phase the size of market levels
off, and organizations tend to have stable
market shares
 Organizations may still be able to increase
profitability reducing costs and making full use
capacity
 However, some Organizations may still try to
increase profitability by increasing capacity if the
believe this stage will be fairly long, or the cost
to increase capacity is relatively small.

 In the decline phase Organization is faced
with underutilization of capacity due to
declining demand
 Organizations may eliminate the excess
capacity by selling it or by introducing new
products or services.
 An option that is sometimes used in
manufacturing is

 To transfer capacity to a location that has
lower labour costs, which allows the
Organization to continue to make a profit on
the product for a while longer.
 3 take a ‘’big-picture’’(i.e. systems) approach
to capacity changes.
 When Developing capacity alternatives , it is
important to consider how parts of the
system interrelate.

 For example ,when making a decision to
increase the number of rooms in a motel,
one should also take into account probable
increased in demand for parking,
entertainment, and food, housekeeping. This
is a ‘’big-picture’’ approach
 The risk in not taking a big-picture approach
is that the system will be unbalanced.

 Evidence of unbalanced system is the existence
of a bottleneck operation.
 A bottleneck operation is an operation in a
sequence of operations whose capacity lower
than the capacities in other operations in the
sequence
 As a consequence, the capacity of the
bottleneck operation limits the system capacity.
 The capacity of the system is reduced to the
capacity of the bottleneck operation .

 4. prepare to deal with capacity ‘’ chunks’’
 Capacity increases are often acquired in
fairly large chunks rather than smooth
increments, making it difficult to achieve a
match between desired capacity and feasible
capacity
 For instance, the desired capacity of a
certain operation maybe 55 units per hour,
but

 Suppose that machines used for his
operation are able to produce 40 units
per hour each
 One machine by itself would cause
capacity to be 15 units per hour short of
what is needed
 But two machines would result in an
excess of capacity of 25 units per hour

DEVELOPING CAPACITY
ALTERNATIVES
 5 attempt to smooth out capacity requirements.
 Unevenness in capacity requirements also
create certain problems
6 Identify the optimal the operating level
Production units typically have an ideal or optimal
level operation in terms of unit cost of output.
At the ideal ,cost per unit is the lowest for that
production unit

EVALUATING ALTERNATIVES
 Cost –volume analysis. manager has the
option of purchasing one, two, or three
machines. fixed cost and potential volumes
are as follows
 Num of total annual
corresponding
 Machines fixed costs range of
o/t
 1 $9600 0 to 300
 2 15,000 301to 600

EVALUATING ALTERNATIVES
 Variable cost is $10 per unit and revenue is
$40 per unit
 A)Determine the break even point for each
range
 B)if the projected annual demand is between
580 and 660 units, how many machines
should the manager purchase

FACILITY LOCATION & LAYOUT
 Layout refers to the configuration of
departments, work centers ,and equipment ,
with particular emphasis on movement of
work(customers or materials) though the
system.
 As in other areas of system design, layout
decisions are important for three basic
reasons

FACILITIES LAYOUT
1) They require substantial investments of
money and effort
2) They involve long term commitments, which
makes mistakes difficult to overcomes
3) They have a significant impact on the cost
and efficiency of the operations

FACILITIES LAYOUT
 The need for layout planning arises both in
the process of designing new facilities and in
redesigning existing facilities
 The most common reasons for redesign of
layouts include inefficient operations (e.g
high cost, bottlenecks),accidents or safety
hazards,
 Changes in the design of products or
services

FACILITIES LAYOUT
 Introduction of products or services
 Changes in the volume of output or mix
 Changes in methods or equipments
 Changes in environmental or other legal
requirements and
 Morale problems ( e.g lack of face to face
contact)

FACILITIES LAYOUT
 Poor layout design can adversely affect
system performance.
 The basic objective of layout design is to
facilitate a smooth flow of work, material ,and
information through the system .
 Supporting objectives generally involve the
following

FACILITIES LAYOUT
 To facilitate attainment of products or services
quality
 To use workers and space efficiently
 To avoid bottlenecks
 To minimize material handing cost
 To eliminate unnecessary movement of workers
or materials
 To minimize production time or customer service
time
 To design for safety

FACILITIES LAYOUT
 The Three basic types of layout are
 Product
 Process and
 Fixed-position
 Product layouts are most conducive to repetitive
processing
 Process are used for intermittent Processing
and Fixed-position are used when projects
require layout.

REPETITIVE PROCESSING: PRODUCT LAYOUTS
 is one in which equipment or work
processes are arranged according to the
progressive steps by which the product is
made.
 Product layouts are used to achieve a
smooth and rapid flow of large volumes of
goods or customers through a system.

 This is made possible by highly standardized
goods or services that allow highly
standardized , repetitive processing.
 The work is divided into a series of
standardized tasks, Permitting specialization
of equipment and division of labour.

 In manufacturing environments, the lines are
referred to as production lines or assembly
lines
 production lines : standardized layout
arranged according to a fixed sequence of
production tasks.+

 Product layouts achieve a high degree of
labour and equipment utilization , which
tends to offset their high equipment costs .
 Because items move quickly from operation
to operation, the amount of work-in-process
is often minimal
 Consequently ,operations are so closely tied
to each other that the entire system is highly
vulnerable to being shut-down because of

 Mechanical failure or high absenteeism
 Eg. Automobile assembly
 fast-food restaurants
 The main advantage of Product layouts are
1. a high rate of output
2. Low unit cost due to high volume.the high
cost of specialized equipment is spread
over many units

 Labour specialization, which reduces training
costs and time ,and results in a wide span of
supervision
 Lower material –handling cost per unit
 High utilization of labour and equipment

 The primary disadvantages of product
layouts include the following
 Poor skilled workers may exhibit interset in
maintaining equipment or in the quality
output
 The system is fairly inflexible in response to
changes in the volume of the output or
changes in product or process design

 The system is highly susceptible to shutdown
caused by equipment breakdowns or
excessive absenteeism because work
stations are highly interdependent

NON- REPETITIVE PROCESSING
:PROCESS LAYOUTS
 process layouts are designed to process
items or provide services that involve a
variety of processing requirements.
 The variety of jobs that are processed
requires frequent adjustments to equipment
 This causes a discontinuous workflow, which
is referred to as intermittent processing

NON- REPETITIVE PROCESSING
:PROCESS LAYOUTS
 The layouts feature departments or
other functional groupings in which
similar kinds of activities are performed
 A manufacturing example of a process
layout is the machine shop, which has
separate departments for milling
,grinding ,drilling , and so on.

NON- REPETITIVE PROCESSING :PROCESS
LAYOUTS
 process layouts are quite common in
service environment
 Because equipment in a process layout
is arranged by type rather than by
processing sequence , the system is
much less vulnerable to shut down
caused by Mechanical failure or
absenteeism

ADVANTAGES AND DISADVANTAGES
 The Advantages of process layouts include
the following
 The system can handle a variety of
processing requirements
 The system are not particularly vulnerable to
equipment failures
 General-purpose equipment is often less
costly than the specialized equipment used
in product layout and is easier and less
costly to maintain

DISADVANTAGES
 In process inventory can be high if batch
processing is used in manufacturing
systems
 Equipment utilization rates low
 Material handling is slow

FIXED –POSITION LAYOUTS
 In Fixed –position layouts, the item being
worked remains stationary , and workers,
materials, and equipments are moved as
needed.

DESIGNING PRODUCT LAYOUTS: LINE
BALANCING
 The goal of a product layout is to arrange
workers or machines in the sequence that
operations need to be performed.
 The sequence is referred to as a production
line or as assembly line
 These lines range from fairly short , with just
a few operations, to long lines that have a
large number of operations

LINE BALANCING
 Line balancing
 The process of assigning tasks to
workstations in such a way that the
workstations have approximately equal time
requirements
 The goal of Line balancing is to obtain task
groupings that represent approximately
equal time requirements. This minimizes the
idle time along the line and result in high
utilization

LINE BALANCING
 Of labour and equipment.
 Idle times occurs if task times are not equal
among workstations; some stations are
capable of producing at higher rates than
others.
 How does a manager decide how many
stations to use?
 The primary determinant is what the line’s
cycle time will be?

LINE BALANCING
 The cycle time is the maximum time allowed
at each work station to perform assigned
tasks before the work moves on.
 The cycle time also establishes the output
rate of a line
 For instance, if The cycle time is two
minutes , units will come off the end of the
line at the rate of one every two minutes

LINE BALANCING
 Suppose that the work required to fabricate a
certain product can be divided up into five
elemental tasks, with the task times and
precedence relationships as following
diagram
 The task times govern the range of possible
cycle times.
0.1 m
0.7m 1m 0.5m 0.2m

LINE BALANCING
 The minimum cycle time is equal to the
longest task time ( 1 minute) and
 The maximum cycle time is equal to the sum
of task times ( 0.1+0.7+1+0.5+0.2=2.5
minutes)
 Output rat= operating time per day
cycle time


LINE BALANCING
 Assume that the line will operate for eight
hours per day( 480 minutes) .with a cycle
time of 1 minute, output would be
 480 minutes per day =480 units per day
1 minute per unit
With a cycle time of 2.5 minutes, output would
be
 480 minutes per day =192 units per day
2.5 minutes per unit

LINE BALANCING
 Assuming that no parallel activities are to be
employed ( e.g.. two lines ), the output
selected for the line must fall in the range of
192 units per day to 480 units per day
 As a general rule , the cycle time determined
by desired output, that is, a desired output is
selected ,and the cycle time is computed.

LINE BALANCING
 If the cycle time does not fall b/n maximum and
minimum bounds, the desired output rate must
be revised.
 cycle time= operating time per day
 desired output rate
 E.g. , suppose that the desired output rate is
480 units
 480 minutes per day= 1 minute per unit
 480 units per day

LINE BALANCING
 The number of workstations that will be
needed is a function of both the desired
output rate and our ability to combine
elemental tasks into workstations
 We can determine the theoretical minimum
number of workstations necessary to provide
a specified rate of output as follows:

LINE BALANCING
 N min = t
cycle time
where
N min= the theoretical minimum number of
stations
t =sum of task times

LINE BALANCING
 Suppose the desired rate of output is the
maximum of 480 units per day.( This will
require a cycle time of 1 minute.)
 The minimum number of stations required to
achieve this goal is
 N min= 2.5 minutes per day unit = 2.5
stations
 1 minute per unit per station


LINE BALANCING
 Because 2.5 stations is not feasible, it is
necessary to round up to three stations
 A very useful tool in line balancing is a
precedence diagram
 A simple precedence diagram
 0.1 min 1min


 0.7min 0.5min 0.2 min
a
b
c d
e

LINE BALANCING
 The general procedure in line balancing is
described as follows
 1 determine the cycle time and the minimum
number of workstations
 2 make assignments to workstations in
order , beginning with station 1 .tasks are
assigned to workstations moving from left to
right through the precedence diagram

LINE BALANCING
 3 )before each assignment, use the following
criteria to determine which tasks are eligible
to be assigned to a workstation:
 A) all preceding tasks in the sequence have
been assigned
 B) the task time does not exceed the time
remaining at the workstation.
 If no tasks are eligible ,move on to the next
workstation

LINE BALANCING
 4) after each task assignment, determine
the time remaining at current workstation by
subtracting the sum of times tasks assigned
to it from the cycle time
 5) break ties that occur using one of these
rules
 A) assign the task with longest task time
 B) assign tasks with the greatest number of
followers

LINE BALANCING
 6) continue until all tasks have been
assigned to workstations
 7) compute the appropriate measures( e.g.
percent idle time, efficiency ) for the set of
assignments.

LINE BALANCING
 Two widely used measures of effectiveness
are
 1) percentage of idle time of the line.
 This is sometimes referred to as the balance
delay
percentage of idle time=idle time per cycle x
100
N actual x cycle time
where
N actual= actual number of station

LINE BALANCING
 percentage of idle time = 0.5 x 100
=16.7%
 3x1
 2) the efficiency of the line .this is
computed as follows
 Efficiency=100% - percent idle time
 Efficiency=100% -16.7%=83.3%

LINE BALANCING
 Using the following information contained in
the table shown, do each of the following
1. Draw a precedence diagram .
2. Assuming an eight-hour workday, compute
the cycle time needed to obtain an output
of 400 units per day.
3. Determine the minimum number of
workstations required

LINE BALANCING
4 assign tasks to workstations using this rule
: assign tasks according to greatest
number of following tasks. In case of a
tie,use the tiebreaker of assigning the task
with the longest processing time first.

LINE BALANCING
task Immediate follower Task time (in minutes)
A B 0.2
B E 0.2
C D 0.8
D F 0.6
E F 0.3
F G 1
g H 0.4
h End 0.3

LINE BALANCING
 Compute the resulting percent idle time and
efficiency the of system.

PRODUCT AND SERVICE DESIGN

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