This document provides an overview of plant location, layout, and line balancing for an industrial management course. It covers factors to consider for plant location such as proximity to materials, labor, transportation and utilities. It also discusses objectives and principles of plant layout such as minimizing movement, uniform flow, and space utilization. Additionally, it describes different types of facility layouts and reasons for redesigning layouts.

1. JJ619 INDUSTRIAL MANAGEMENT PLANT LOCATION, LAYOUT AND LINE BALANCING
CHAPTER 2
JABATAN KEJURUTERAAN MEKANIKAL
POLITEKNIK SULTAN HAJI AHMAD SHAH

2. SUMMARY
This topic covers plan location and
layout, facilities layout, processes
selection, line balancing and network
analysis.

3. COURSE LEARNING OUTCOMES
Students should be able to :
Apply the basic concept of industrial management system in industry.
Produce the suitable plant layout according to product flow process and safety requirement.
Identify the suitable concept industrial management system in related industry
by group.

4. PLANT LOCATION
 Holmes defines plant location problem as one
of determining
“That location which, in consideration of
all factors affecting products delivered to
customers cost of product to be
manufactured, will afford the enterprise
he greatest advantages obtained by
virtue of location”.

5. PLANT LAYOUT
According to Moore; DEFINATION of plant layout
“is a plan of an optimum arrangement of facilities including personnel, operating equipment, storage space, material handling equipment and all other supporting services along with the design of best structure to contain all these facilities”.
The overall objective of plant layout is to design a physical arrangement that meets the required output quality and quantity most economically.

6. INTRODUCTION
Site selection is an important activity as it decides the fate of the business.
 A good location will reduce the cost of production &distribution to a large extent. The reduction of cost of distribution helps in elevating either the competitive strength or the profit margin of business.
Locating of business involves large & relatively permanent investment.
If the site selection is not done properly, all the money spent on factory building, machinery & their installation will go in waste & the owner has to suffer great loss.
Therefore the site for factory should be selected very carefully. While selecting a site it is necessary to consider technical, commercial, &financial aspects & then select a site that may provide maximum profit.

7. CONCEPT OF PLANT LAYOUT
Need for location because of this situation :
•While starting a new factory
•During expansion of existing plant
•When existing plant is to be re-located at some other place
Steps( Procedure) in choosing Location
National Decision
Regional Decision
Community Decision
Site Decision
Political, social, economic stability;
Currency exchange rates; . . . . .
Climate; Customer concentrations; Degree of unionization; . . . . .
Transportation system availability;
Preference of management; . . . . .
Site size/cost; Environmental impact; Zoning restrictions; . . . . .

8. FACTORS OF PLANT LOCATION
Selection of region – Factors
Availability of raw materials
Nearness to market
Availability of power
Transport facilities
Suitability of climate
Goverment policy
Competition between states
Selection of community/locality (factors)
Availability of labour
Civic amenities for workers
Existence of complementary & competing industries
Finance & research facilities
Availability of water & fire-fighting facilities
Local taxes & restrictions
Momentum of early start
Personal factors
Disposal of waste

9. FACTORS OF PLANT LOCATION
Selection of a particular site (factors)
Condition that demand city (urban) location, sub-urban location and rural location.
Example :

10. FACTORS (CONT.)
RAW MATERIALS AVAILABILITY:
The source of raw materials is one of the most important factors influencing the selection of a plant site. This is particularly true for the sulfuric acid plant because large volumes of sulfur is consumed in the process which will result in the reduction of the transportation and storage charges. Attention should be given to the purchased price of the raw materials, distance from the source of supply, freight and transportation expenses, availability and reliability of supply, purity of raw materials and storage requirements.
LOCATION:
The location of markets or intermediate distribution centers affects the cost of product distribution and time required for shipping. Proximity to the major markets is an important consideration in the selection of the plant site, because the buyer usually finds advantageous to purchase from near-by sources. In case of sulfuric acid plant, the major consumers are fertilizer industries and hence the plant should be erected in close proximity to those units.
AVAILABILITY OF SUITABLE LAND:
The characteristics of the land at the proposed plant site should be examined carefully. The topography of the tract of land structure must be considered, since either or both may have a pronounced effect on the construction costs. The cost of the land is important, as well as local building costs and living conditions. Future changes may make it desirable or necessary to expand the plant facilities. The land should be ideally flat, well drained and have load-bearing characteristics. A full site evaluation should be made to determine the need for piling or other special foundations
ENVIRONMENTAL IMPACT AND EFFLUENT DISPOSAL:
Facilities must be provided for the effective disposal of the effluent without any public nuisance. In choosing a plant site, the permissible tolerance levels for various effluents should be considered and attention should be given to potential requirements for additional waste treatment facilities. As all industrial processes produce waste products, full consideration must be given to the difficulties and coat of their disposal. The disposal of toxic and harmful effluents will be covered by local regulations, and the appropriate authorities must be consulted during the initial site survey to determine the standards that must be met.

11. FACTORS (CONT.)
TRANSPORT:
The transport of materials and products to and from plant will be an overriding consideration in site selection. If practicable, a site should be selected so that it is close to at least two major forms of transport: road, rail, waterway or a seaport. Road transport is being increasingly used, and is suitable for local distribution from a central warehouse. Rail transport will be cheaper for the long-distance transport. If possible the plant site should have access to all three types of transportation. There is usually need for convenient rail and air transportation facilities between the plant and the main company head quarters, and the effective transportation facilities for the plant personnel are necessary.
AVAILABILITY OF LABORS:
Labors will be needed for construction of the plant and its operation. Skilled construction workers will usually be brought in from outside the site, but there should be an adequate pool of unskilled labors available locally; and labors suitable for training to operate the plant. Skilled tradesmen will be needed for plant maintenance. Local trade union customs and restrictive practices will have to be considered when assessing the availability and suitability of the labors for recruitment and training.
AVAILABILITY OF UTILITIES:
The word “utilities” is generally used for the ancillary services needed in the operation of any production process. These services will normally be supplied from a central facility and includes Water, Fuel and Electricity which are briefly described as follows:
Water: The water is required for large industrial as well as general purposes, starting with water for cooling, washing, steam generation and as a raw material in the production of sulfuric acid. The plant therefore must be located where a dependable water supply is available namely lakes, rivers, wells, seas. If the water supply shows seasonal fluctuations, it’s desirable to construct a reservoir or to drill several standby wells. The temperature, mineral content, slit and sand content, bacteriological content, and cost for supply and purification treatment must also be considered when choosing a water supply. Demineralized water, from which all the minerals have been removed is used where pure water is needed for the process use, in boiler feed. Natural and forced draft cooling towers are generally used to provide the cooling water required on site.
Electricity: Power and steam requirements are high in most industrial plants and fuel is ordinarily required to supply these utilities. Power, fuel and steam are required for running the various equipments like generators, motors, turbines, plant lightings and general use and thus be considered as one major factor is choice of plant site.

12. FACTORS (CONT.)
LOCAL COMMUNITY CONSIDERATIONS:
The proposed plant must fit in with and be acceptable to the local community. Full
consideration must be given to the safe location of the plant so that it does not impose a
significant additional risk to the community.
CLIMATE :
Adverse climatic conditions at site will increase costs. Extremes of low temperatures will
require the provision of additional insulation and special heating for equipment and
piping. Similarly, excessive humidity and hot temperatures pose serious problems and
must be considered for selecting a site for the plant. Stronger structures will be needed at
locations subject to high wind loads or earthquakes.
POLITICAL AND STRATEGIC CONSIDERATIONS :
Capital grants, tax concessions, and other inducements are often given by governments to
direct new investment to preferred locations; such as areas of high unemployment. The
availability of such grants can be the overriding consideration in site selection.
TAXATION AND LEGAL RESTRICTIONS:
State and local tax rates on property income, unemployment insurance, and similar items
vary from one location to another. Similarly, local regulations on zoning, building codes,
nuisance aspects and others facilities can have a major influence on the final choice of the
plant site.

13. OBJECTIVES OF PLANT LAYOUT
The main objective consists of organizing equipment and working areas in the most efficient way, and at the same time satisfactory and safe for the personnel doing the work.
Sense of Unity
The feeling of being a unit pursuing the same objective.
Minimum Movement of people, material and resources.
Safety
In the movement of materials and personnel work flow.
Flexibility
In designing the plant layout taking into account the changes over short and medium terms in the production process and manufacturing volumes.

14. OBJECTIVES OF PLANT LAYOUT
These main objectives are reached through the attainment of the following facts:
Congestion reduction.
Elimination of unnecessary occupied areas.
Reduction of administrative and indirect work.
Improvement on control and supervision.
Better adjustment to changing conditions.
Better utilization of the workforce, equipment and services.
Reduction of material handling activities and stock in process.
Reduction on parts and quality risks.
Reduction on health risks and increase on workers safety.
Moral and workers satisfaction increase.
Reduction on delays and manufacturing time, as well as increase in production capacity.
All these factors will not be reached simultanesly, so the best solution will be a balance among them.

15. PRINCIPLES OF PLANT LAYOUT
 Overall integration of factors,
 Minimum movement,
 Uni-direction flow,
 Effective use of available space,
 Maximum visibility,
 Maximum accessibility.

16. PRINCIPLES OF PLANT LAYOUT (CONT.)
Overall integration of factors:
 A good layout is one that integrates men, materials, machines and supporting activities and others in a way that the best compromise is obtained No layout can satisfy each and every principle of a good layout. Some criterion may conflict with some other criterion and as a result no layout can be ideal it has to integrate all factors into the best possible compromise.
Minimum movement:
A good layout is one that permits the minimum movement between the operations. The plant and machinery in case of product layout and departments in case of process layout should be arranged as per sequence of operations of most of the products.
Since straight line is the shortest distance between any two points, men and materials as far as possible should be made to move along the straight path
A door may be made in a wall or a hole may be drilled in a ceiling if that eliminates or reduces material handling in place of stairs or a distant door.

17. PRINCIPLES OF PLANT LAYOUT (CONT.)
Uni-direction flow:
A good layout is one that makes the materials move only in the forward direction, towards stage of completion, with any backtracking.
Since straight line is the shortest distance between any two, points, materials as far as possible should be made to move on the principle of straight-line flow. And when straight line flow is not possible, other flows like U-shaped flow, circular flow or zig zag flow may be adopted, but the layout may ensure that materials move in the forward direction.
To ensure forward flow, equipment if necessary may be duplicated.
Effective use of available space:
 A good layout is one that makes effective use of available space both horizontal and vertical.
Backtracking and duplicated movements consume more time, involve un- necessary materials handling, add to cost and lead to inefficiency.
Raw materials, work-in-progress and finished goods should be piled vertically one above another rather than being strewn on the floor.
Pallets or equivalents should be made use of to pile up several layers one above another.
Area below the work tables or in the cupboards built into the wall are welcome since they reduce requirement of space.

18. PRINCIPLES OF PLANT LAYOUT (CONT.)
Maximum visibility:
A good layout is one that makes men, machines and materials ready observable at all times.
All departments should be smoothly integrated, convenient to service and easy to supervise.
Every piece of positioning or screening or partitioning should be scrutinized and carefully planned.
Special cupboards, enclosures, offices, partitions etc. should be avoided except when their utility is established beyond doubt.
Maximum accessibility:
A good layout is one that makes all servicing and maintenance point readily accessible.
Machines should be kept sufficiently apart and with reasonable clearance from the wall so that lubrication, adjustment and replacement of belts, removal of parts at the time of repairs etc can be done conveniently by the maintenance staff.
Area in front of electrical panels and fire extinguishers should be kept free from obstructions.

19. PLANT LAYOUT PROCEDURE
Plant Layout Procedure - Phase 1 Information Gathering
Determine what will be produced
Determine how many will be produced
Determine what components will be made or purchased
Determine required operations
Determine sequence of operations
Set time standards for each operation
Plant Layout Procedure - Phase 2 Production and Flow Analysis
Determine the plant rate, R
Determine the number of machines
Balance production lines
Study the flow requirement
Determine activity relationships
Layout each workstation

20. PLANT LAYOUT PROCEDURE (C0NT.)
Plant Layout Procedure - Phase 3 Support Services
Identify needs for personal and plant services
Identify office needs
Develop total space requirements
Select material handling equipment
Allocated area
Develop plot plan and building shape
Plant Layout Procedure - Phase 4 Implementation and
Evaluation
Construct master plan
Seek input and adjust
Seek approvals
Install
Start up
Follow up

21. FACILITIES LAYOUT
DEFINITION :
A facility layout is an arrangement of everything needed for production of goods or delivery of services.
A facility is an entity that facilitates the performance of any job. It may be a machine tool, a work centre, a manufacturing cell, a machine shop, a department, a warehouse, etc. (Heragu, 1997).

22. REASON FOR FACILITIES LAYOUT
Reason :
Minimize delays in materials handling and customer movement.
Maintain flexibility.
Use labor and space effectively.
Promote high employee morale and customer satisfaction.
Provide for good housekeeping and maintenance.
Enchange sales as appropriate in manufacturing and service.
What type of facility would be helpful :
Because the facility is not functional - (poor layout / traffic pattern / not easy to use).
Because the facility is getting new equipment (like a kitchen cooking facility).
Because the facility is going to need to provide for more guests.
Because due to a poor former design, the facility is failing as in structural deficiency.
Because the owner has a lot of money.. and wants to re-design the facility to make it more modern.

23. REASON (CONT.)
Symptoms that allow us to detect the need for a re-layout:
Congestion and bad utilization of space.
Excessive stock in process at the facility.
Long distances in the work flow process.
Simultaneous bottle necks and workstations with idle time.
Qualified workers carrying out too many simple operations.
Labor anxiety and discomfort. Accidents at the facility.
Difficulty in controlling operations and personnel.

24. CATEGORIZE TYPES OF LAYOUT
From the point of view of plant layout, we can classify small business or unit into three categories:
1. Manufacturing units
2. Traders
3. Service Establishments

25. 1. MANUFACTURING UNITS
In case of manufacturing unit, plant layout may be of four types:
(a) Product or line layout
(b) Process or functional layout
(c) Fixed position or location layout
(d) Combined or group layout

26. (A) PRODUCT OR LINE LAYOUT
Under this, machines and equipments are arranged in one line depending upon the sequence of operations required for the product.
The materials move form one workstation to another sequentially without any backtracking or deviation.
Under this, machines are grouped in one sequence. Therefore materials are fed into the first machine and finished goods travel automatically from machine to machine, the output of one machine becoming input of the next, e.g. in a paper mill, bamboos are fed into the machine at one end and paper comes out at the other end.
The raw material moves very fast from one workstation to other stations with a minimum work in progress storage and material handling.
The grouping of machines should be done keeping in mind the following general principles.
a) All the machine tools or other items of equipments must be placed at the point demanded by the sequence of operations
b) There should no points where one line crossed another line.
c) Materials may be fed where they are required for assembly but not necessarily at one point.
d) All the operations including assembly, testing packing must be included in the line

27. PRODUCT OR LINE LAYOUT (CONT.)
 A line layout for two products is given below:
 Product A
 Product B
Turning Milling Drilling Assembly Inspection Package
Operation operation operation despatch
Planer Grinding Milling Lathe Inspection Package
Operation operation operation operation despatch

28. (B) PROSES LAYOUT
In this type of layout machines of a similar type are arranged together at one place. E.g. Machines performing drilling operations are arranged in the drilling department, machines performing casting operations be grouped in the casting department.
Therefore the machines are installed in the plants, which follow the process layout. Hence, such layouts typically have drilling department, milling department, welding department, heating department and painting department etc.
The process or functional layout is followed from historical period. It evolved from the handicraft method of production.
The work has to be allocated to each department in such a way that no machines are chosen to do as many different job as possible i.e. the emphasis is on general purpose machine.
The work, which has to be done, is allocated to the machines according to loading schedules with the object of ensuring that each machine is fully loaded.

29. PROCESS LAYOUT (CONT.)
Process layout is shown in the following diagram:
Milling Lathe Assembly Shipping And Welding Grinder Inspection Receiving Painting

30. (C) FIXED POSITION OR LOCATION LAYOUT
 In this type of layout, the major product
being produced is fixed at one location.
 Equipment labour and components are
moved to that location.
 All facilities are brought and arranged
around one work centre. This type of layout
is not relevant for small scale entrepreneur.

31. FIXED LAYOUT (CONT.)
The following figure shows a fixed position layout regarding ship building :
man / labor machine Ship material / equipment building stationary

32. (D) COMBINED LAYOUT
Certain manufacturing units may require all three processes namely intermittent process (job shops), the continuous process (mass production shops) and the representative process combined process [i.e. miscellaneous shops].
In most of industries, only a product layout or process layout or fixed location layout does not exist.
Thus, in manufacturing concerns where several products are produced in repeated numbers with no likelihood of continuous production, combined layout is followed.
Generally, a combination of the product and process layout or other combination are found, in practice, e.g. for industries involving the fabrication of parts and assembly, fabrication tends to employ the process layout, while the assembly areas often employ the product layout.
In soap, manufacturing plant, the machinery manufacturing soap is arranged on the product line principle, but ancillary services such as heating, the manufacturing of glycerin, the power house, the water treatment plant etc. are arranged on a functional basis.

33. (D) COMBINED LAYOUT (CONT.)
The following figure shows a combined position layout :
Process Layout Product Layout Produce various operation Manufacturing various component parts Assembly Stamping Welding Heat treatment A B C D E

34. 2. TRADERS
When two outlets carry almost same merchandise, customers usually buy in the one that is more appealing to them. Thus, customers are attracted and kept by good layout i.e. good lighting, attractive colours, good ventilation, air conditioning, modern design and arrangement and even music.
All of these things mean customer convenience, customer appeal and greater business volume. The customer is always impressed by service, efficiency and quality.
Hence, the layout is essential for handling merchandise, which is arranged as per the space available and the type and magnitude of goods to be sold keeping in mind the convenience of customers.
There are three kinds of layouts in retail operations today.
(a) Self service or modified self service layout
(b) Full service layout
(c) Special layouts

35. 2. TRADERS (CONT.)
The self-service layouts, cuts down on sales clerk’s time and allow customers to select merchandise for themselves. Customers should be led through the store in a way that will expose them to as much display area as possible, e.g. Grocery Stores or department stores. In those stores, necessities or convenience goods should be placed at the rear of the store. The use of colour and lighting is very important to direct attention to interior displays and to make the most of the stores layout.
All operations are not self-service. Certain specialty enterprises sell to fewer numbers of customers or higher priced product, e.g. Apparel, office machines, sporting goods, fashion items, hardware, good quality shoes, jewellery, luggage and accessories, furniture and appliances are all examples of products that require time and personal attention to be sold. These full service layouts provide area and equipment necessary in such cases.
Some layouts depend strictly on the type of special store to be set up, e.g. TV repair shop, soft ice cream store, and drive-in soft drink stores are all examples of business requiring special design. Thus, good retail layout should be the one, which saves rent, time and labour.

36. 3. SERVICES CENTERS AND ESTABLISHMENT
Services establishments such as motels, hotels, restaurants, must give due attention to client convenience, quality of service, efficiency in delivering services and pleasing office ambience.
In today’s environment, the clients look for ease in approaching different departments of a service organization and hence the layout should be designed in a fashion, which allows clients quick and convenient access to the facilities offered by a service establishment.

37. PLANT LAYOUT PROCESSES SELECTION
Process selection
Deciding on the way production of goods or services will be organized.
Major implications
Capacity planning
Layout of facilities
Equipment, Capital-equipment or labor intensive
Design of work systems
New product and service, technological changes, and competitive pressures.

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

39. QUESTIONS BEFORE SELECTING A
PROCESS
 Variety of products and services
 How much
 Flexibility of the process; volume, mix,
technology and design
 What type and degree
 Volume
 Expected output

40. PROCESS TYPES
Job Shops:
Small lots, low volume, general equipment, skilled workers, high-variety. Ex : tool and die shop, veterinarian’s office.
Batch Processing:
Moderate volume and variety. Variety among batches but not inside. Ex : paint production , BA3352 sections.
Repetitive/Assembly:
Semicontinuous, high volume of standardized items, limited variety. Ex : auto plants, cafeteria.
Continuous Processing:
Very high volume an no variety. Ex : steel mill, chemical plants.
Projects:
Nonroutine jobs. Ex : preparing BA3352 midterm.

41. LINE BALANCING
Line balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements. This results in the minimized idle time along the line and high utilization of labor and equipment.
Assembly line balancing is associated with a product layout in which products are processed as they pass through a line of work centres. An assembly line can be considered as a “PRODUCTION SEQUENCE” where parts are assembled together to form an end product. The operations are carried out at different workstations situated along the line.

42. LINE BALANCING CONCEPT
The step in line balancing :
1) The minimization of the number of workstations;
2) The minimization of cycle time;
3) The maximization of workload smoothness;
4) The maximization of work relatednes.
Reasons to have balance the production line :
(1) Keeping inventory cost slow results in higher net income;
(2) Keeping normal inventory levels lets the operator work all day long giving him/her the opportunity to earn more money by increasing his/her efficiency;
(3) Keeping the line balanced let’s the supervisors improve other areas because they can use their time better;
(4) Balanced production keeps prices low which turns into repeat sales;
(5) Balanced production means better production.

43. LINE BALANCING CONCEPT (CONT.)
There are 3 rules for balancing:
(1) Have at least ½ hour of WIP for each operation;
(2) Solve problems before they become any larger;
(3) Meet production goals by keeping every operator working at their
maximum capacity.
Line balancing is the act of balancing the cycle time of the workers on a production line to the takt time.
Takt time is the required pace of production to meet customer demand. The word takt comes from the German word for the baton used by an orchestra conductor.
When everyone has a cycle time that matches the takt time, work flows efficiently. If a line is not balanced, it either has waiting waste where team members are standing around at the end of each cycle, or the line can’t keep up with demand.
The total cycle time to produce a product divided by the takt time gives the number of people required. This assumes that the work can be split evenly— sometimes it can be hard to do precise line balancing. Most lines never get balanced out perfectly even.
Consolidating all this extra time makes it easy to shift a person to another location when a few improvements are completed. It also gives that person a bigger chunk of time to work on projects. This practice of line balancing is known as the least operator concept.

44. DESIGNING PRODUCT LAYOUTS
The main objective of a product layout is to arrange workers or machines in a line according to the operations that need to be performed.
Thus it would seem that the layout could be determined by following the order of assembly.
To maximize efficiency on the assembly line balancing must be considered.
Line balancing - attempt to equalize the amount of work at each work station.
Line Balancing cuts down on idle time for the workers.

45. LINE BALANCING IN PRODUCT DESIGN LAYOUT
Some definitions :
Workstation : A work station is a location on assembly line
where given amount of work is performed.
Cycle time : it is the amount of time for which a unit that
is assembled is available to any operator on the line or it is
the time the product spends at each work station.
Task : The smallest grouping of work that can be assigned
to a workstation.
Predecessor Task : A task that must be performed before
performing another (successor) task.
Task time : Standard time to perform element task.
Station time : Total standard work content of specific
workstation.
Balance Delay (BD) : Percentage of total idle time on the
line to total time spent by the product from beginning to
end of line.

46. LINE BALANCING IN PRODUCT DESIGN LAYOUT
The parameters in line balancing :
Cycle time (CT) = Available time period = AT .
Output units required/period Output
Minimum number of workstation = Total time
Cycle time
Line efficiency (LE) = Total station time x 100
Cycle time x no. of workstations
Balance delay (BD) = Total idle time for all workstations x100
Total available working time on all stations
= 1 – LE

47. EXAMPLE 1:
In one company, production time available per day is 480 minutes and 40 units are required per day. The data is shown below for nine tasks. TASK TIME PRIORITY OF TASK A 10 - B 11 A C 5 B D 4 B E 12 A F 3 C , D G 7 F H 11 E I 3 G , H TOTAL TIME 66

48. QUESTION 1 :
Determine :
1. Identify precedence diagram.
 2. Calculate:
 i. Cycle time,
 ii. Minimum number of workstations,
 iii. Assign the work elements to
workstations.

49. SOLUTION 1:
1. Precedence diagram
5 10 11 C 3 7 A B F G 4 D 3 I 12 11 E H

50. SOLUTION 1:
2. Calculate :
i) Cycle time = 480 = 12 minutes/unit
40
ii) Minimum number of workstation
= 66
12
= 5.5 or 6 stations

51. SOLUTION 1 :
iii) Assign the workstation:
S4 S1 S2 5 S6 10 11 C 3 7 A B F G 4 D 3 S3 S5 I 12 11 E H

52. EXAMPLE 2:
The company I engaged in the assembly of a wagon on a conveyor. 500 wagons are required per day. Production time available per day is 420 minutes. The other information is given below regarding assembly steps and precedence relationships.
Task Time (sec) Task that must precede A 45 - B 11 A C 9 B D 50 - E 15 D F 12 C G 12 C H 12 E I 12 E J 8 F , G , H , I K 5 J Total 191 -

53. QUESTION 2 :
 i) Draw the precedence diagram.
 ii) Calculate the cycle time.
 iii) Determine the minimum number
of work stations.
 iv) Group of work stations accordingly.
 v) Find the line efficiency.

54. SOLUTION 2 :
i) Draw the precedence diagram.
11 9 12 B C F A 45 G 12 50 15 12 8 9 D E H J K 12 I

55. SOLUTION 2 :
ii) Cycle time.
Cycle time (CT) = Available time period = AT .
Output units required/period Output
= 420 x 60
500
= 50.4 sec
iii) The minimum number of work stations, N.
 N = Total time
Cycle time
= 191
50.4
= 3.79 ≈ 4 work stations

56. SOLUTION 2 :
iv) Group of work stations accordingly.
S3 S1 B C F A S4 G S2 D E H J K I

57. SOLUTION 2 :
v) The line effiency.
 Line efficiency = Total station line x 100
(LE) Cycle time x no. of work stations
= 191 x 100
50.4 x 4
= 94.74%

58. NETWORK ANALYSIS
Introduction :
Network analysis is the general name given to certain specific techniques which can be used for the planning, management and control of projects.
 One definition of a project:
“A project is a temporary endeavour undertaken to create a "unique" product or service”
Network analysis is a vital technique in Project Management. It enables us to take a systematic quantitative structured approach to the problem of managing a project through to successful completion. Moreover, as will become clear below, it has a graphical representation which means it can be understood and used by those with a less technical background.

59. NETWORK ANALYSIS (CONT.)
The Network Diagram :
In a project, an activity is a task that must be performed and an event is a milestone marking the completion of one or more activities. Before an activity can begin, all of its predecessor activities must be completed. Project network models represent activities and milestones by arcs and nodes.
Two different techniques for network analysis were developed independently in the late 1950's - these were:
PERT (for Program Evaluation and Review Technique); and
CPM (for Critical Path Management).

60. OBJECTIVES OF CPM AND PERT
 A powerful coordinating tool for planning,
scheduling and controlling of projects.
 Minimization of total project cost and time
 Effective utilization of resources and
minimization of effective resources.
 Minimization of delays and interruption
during implementation of the project.

61. APPLICATIONS OF CPM AND PERT
Research and development projects.
Equipment maintenance and overhauling.
Construction projects (building, bridges, dams).
Setting up new industries.
Planning and launching of new products.
Design of plants, machines and systems.
Shifting the manufacturing location from one location to another.
Control of production in large job shops.
Market penetration programs.
Organization of big programs, conferences.

62. COMPARISON BETWEEN CPM AND PERT
No. CPM PER 1 Activity oriented Event oriented 2 Used when the activity times are deterministic. Uses a probabilistic time. 3 One time estimate. Three time estimates; a) optimistic, b) most likely, c) pessimistic. 4 Directly introduces cost concept analysis. Indirectly currents for costs. 5 Planning device. Control device.

63. CRITICAL PATH METHOD (CPM)
DuPont developed a Critical Path Method (CPM) designed to address the challenge of shutting down chemical plants for maintenance and then restarting the plants once the maintenance had been completed.
Complex project, like the above example, require a series of activities, some of which must be performed sequentially and others that can be performed in parallel with other activities. This collection of series and parallel tasks can be modeled as a network.
CPM models the activities and events of a project as a network. Activities are shown as nodes on the network and events that signify the beginning or ending of activities are shown as arcs or lines between the nodes. The Figure 1.0 shows an example of a CPM network diagram:

64. FIGURE 1.0 : CPM NETWORK

65. CRITICAL PATH METHOD (CPM)
Critical Path Method (CPM) is a procedure for using network analysis to identify those tasks which are on the critical path; (where any delay in the completion of these tasks will lengthen the project timescale, unless action is taken).
For all tasks off the critical path, a degree of tolerance is possible (late start, late completion, early start).
Network charts and CPM analysis used to be carried out by hand.
Software is now available which requires the user only to enter the tasks, duration of each task and dependencies upon other tasks; a network chart and CPM is then automatically created.

66. STEPS IN CPM PROJECT PLANNING
1. Specify the individual activities
All the activities in the project are listed. This list can be used as the basis for adding sequence and duration information in later steps.
2. Determine the sequence of the activities
Some activities are dependent on the completion of other activities. A list of the immediate predecessors of each activity is useful for constructing the CPM network diagram.
3. Draw the Network Diagram
Once the activities and their sequences have been defined, the CPM diagram can be drawn. CPM originally was developed as an activity on node network.
4. Estimate activity completion time
The time required to complete each activity can be estimated using past experience. CPM does not take into account variation in the completion time.

67. STEPS IN CPM PROJECT PLANNING
5. Identify the Critical Path
The critical path is the longest-duration path through the network. The significance of the critical path is that the activities that lie on it cannot be delayed without delaying the project. Because of its impact on the entire project, critical path analysis is an important aspect of project planning.
The critical path can be identified by determining the following four parameters for each activity:
• ES - earliest start time: the earliest time at which the activity can start given that its precedent activities must be completed first.
• EF - earliest finish time, equal to the earliest start time for the activity plus the time required to complete the activity.
• LF - latest finish time: the latest time at which the activity can be completed without delaying the project.
• LS - latest start time, equal to the latest finish time minus the time required to complete the activity.

68. STEPS IN CPM PROJECT PLANNING
The slack time for an activity is the time between its earliest and latest start time, or between its earliest and latest finish time. Slack is the amount of time that an activity can be delayed past its earliest start or earliest finish without delaying the project.
The critical path is the path through the project network in which none of the activities have slack, that is, the path for which ES=LS and EF=LF for all activities in the path. A delay in the critical path delays the project. Similarly, to accelerate the project it is necessary to reduce the total time required for the activities in the critical path.
6. Update CPM diagram
As the project progresses, the actual task completion times will be known and the network diagram can be updated to include this information. A new critical path may emerge, and structural changes may be made in the network if project requirements change.

69. CPM BENEFITS AND LIMITATIONS
CPM Benefits
Provides a graphical view of the project.
Predicts the time required to complete the project.
Shows which activities are critical to maintaining the schedule and which are not.
CPM Limitations
While CPM is easy to understand and use, it does not consider the time variations that can have a great impact on the completion time of a complex project. CPM was developed for complex but fairly routine projects with minimum uncertainty in the project completion times. For less routine projects there is more uncertainty in the completion times, and this uncertainty limits its usefulness.

70. WHY THE CPM?
The formally identifies tasks which must be completed on time for the whole project to be completed on time.
Identifies which tasks can be delayed for a while if resource needs to be reallocated to catch up on missed tasks.
It helps you to identify the minimum length of time needed to complete a project.
The CPM determines both the early start and the late start date for each activity in the schedule.

71. PERT
The Program Evaluation and Review Technique (PERT) is a network model that allows for randomness in activity completion times. PERT was developed in the late 1950's for the U.S. Navy's Polaris project having thousands of contractors. It has the potential to reduce both the time and cost required to complete a project.
Hence there was a strategic emphasis on completing the Polaris project as quickly as possible, cost was not an issue. However no one had ever build a submarine launched intercontinental ballistic missile before, so dealing with uncertainty was a key issue. PERT has the ability to cope with uncertain activity completion times (e.g. for a particular activity the most likely completion time is 4 weeks but it could be any time between 3 weeks and 8 weeks).

72. PERT (CONT.)
The Network Diagram
In a project, an activity is a task that must be performed and an event is a milestone marking the completion of one or more activities. Before an activity can begin, all of its predecessor activities must be completed. Project network models represent activities and milestones by arcs and nodes.
PERT is typically represented as an activity on arc network, in which the activities are represented on the lines and milestones on the nodes. The Figure 2.0 shows a simple example of a PERT diagram.
The milestones generally are numbered so that the ending node of an activity has a higher number than the beginning node. Incrementing the numbers by 10 allows for new ones to be inserted without modifying the numbering of the entire diagram. The activities in the above diagram are labeled with letters along with the expected time required to complete the activity.

73. FIGURE 2.0 : PERT NETWORK

74. STEPS IN PERT PLANNING PROCESS
PERT planning involves the following steps:
1. Identify activities and milestones
The activities are the tasks required to complete the project. The milestones are the events marking the beginning and end of one or more activities.
2. Determine activity sequence
This step may be combined with the activity identification step since the activity sequence is known for some tasks. Other tasks may require more analysis to determine the exact order in which they must be performed.
3. Construct the Network Diagram
Using the activity sequence information, a network diagram can be drawn showing the sequence of the serial and parallel activities.
4. Estimate activity times
Weeks are a commonly used unit of time for activity completion, but any consistent unit of time can be used. A distinguishing feature of PERT is its ability to deal with uncertainty in activity completion times. For each activity, the model usually includes three time estimates:
Optimistic time (OT) - generally the shortest time in which the activity can be completed. (This is what an inexperienced manager believes!)
Most likely time (MT) - the completion time having the highest probability. This is different from expected time. Seasoned managers have an amazing way of estimating very close to actual data from prior estimation errors.
Pessimistic time (PT) - the longest time that an activity might require.

75. STEPS IN CPM PROJECT PLANNING
5. Determine the Critical Path
The critical path is determined by adding the times for the activities in each sequence and determining the longest path in the project. The critical path determines the total time required for the project.
If activities outside the critical path speed up or slow down (within limits), the total project time does not change. The amount of time that a non-critical path activity can be delayed without delaying the project is referred to as slack time.
If the critical path is not immediately obvious, it may be helpful to determine the following four quantities for each activity:
 ES - Earliest Start time
 EF - Earliest Finish time
 LS - Latest Start time
 LF - Latest Finish time
These times are calculated using the expected time for the relevant activities. The ES and EF of each activity are determined by working forward through the network and determining the earliest time at which an activity can start and finish considering its predecessor activities.

76. STEPS IN CPM PROJECT PLANNING
The latest start and finish times are the latest times that an activity can start and finish without delaying the project. LS and LF are found by working backward through the network. The difference in the latest and earliest finish of each activity is that activity's slack. The critical path then is the path through the network in which none of the activities have slack.
The variance in the project completion time can be calculated by summing the variances in the completion times of the activities in the critical path. Given this variance, one can calculate the probability that the project will be completed by a certain date.
Since the critical path determines the completion date of the project, the project can be accelerated by adding the resources required to decrease the time for the activities in the critical path. Such a shortening of the project sometimes is referred to as project crashing.
6. Update as project progresses
Make adjustments in the PERT chart as the project progresses. As the project unfolds, the estimated times can be replaced with actual times. In cases where there are delays, additional resources may be needed to stay on schedule and the PERT chart may be modified to reflect the new situation.

77. BENEFITS AND LIMITATIONS OF PERT
Benefits of PERT
PERT is useful because it provides the following information:
 Expected project completion time.
 Probability of completion before a specified date.
 The critical path activities that directly impact the completion time.
 The activities that have slack time and that can lend resources to critical path activities.
 Activities start and end dates.
Limitations of PERT
The following are some of PERT's limitations:
 The activity time estimates are somewhat subjective and depend on judgment. In cases where there is little experience in performing an activity, the numbers may be only a guess. In other cases, if the person or group performing the activity estimates the time there may be bias in the estimate.
 The underestimation of the project completion time due to alternate paths becoming critical is perhaps the most serious.

78. TERMS ARE USED
Network – A graphical representation of the project and it consists of series of activities arranged in a logical sequence and show the interrelationship between the activities.
Activities – A physically identifiable part of the project, which consumes time and resources. Each activity has a definite start and end . Activity is represented by an arrow ( ).
Event – An event represents the start or the completion of an activities. The beginning and end points of an activity are events.
Example : Machining a component is an activity
Start machining is an event
Machining completed is an event
Tail event head event

79. TERMS ARE USED (CONT.)
Predecessor activities – All those activities, which must be completed before starting he activity under consideration.
Successor activities – all the activities which have to follow the activity under consideration.
Path – an unbroken chain of activities between two events.
Dummy activity – an activity which depicts the dependency or relationship over the other but does not consume time or resources. It is indicated by a dotted line ( ).
Critical activity – activity with zero float.

80. TERMS ARE USED (CONT.)
Critical path is the sequence of activities which add up to the longest overall duration. It is the shortest time possible to complete the project. Any delay of an activity on the critical path directly impacts the planned project completion date (there is no float on the critical path). A project can have several, parallel, near critical paths. An additional parallel path through the network with the total durations shorter than the critical path is called a sub-critical or non-critical path.
Resource leveling – iterative process of assigning crews to activities in order to calculate their duration.

81. NETWORK / PRECEDENCE DIAGRAM
Any schematic display of the logical relationships of project activities.
Diagram of project activities that shows sequential relationships by use of arrows and nodes.
Example : A sample set of project network.

82. BUILDING A PRECEDENCE DIAGRAM

83. NETWORK ANALYSIS
There are TWO (2) ways of displaying a project network :
1. Activity – on – arrow (AOA)
Network diagram convention in which
arrows designate activities.
2. Activity – on – node (AON)
Network diagram convention in which nodes designate activities.

84. EXAMPLE 1 :
Table 1
Create i. AOA network, and
ii. AON network.
Task
Predecessor
A
-
B
-
C
a
D
b
E
b
F
c, d
G
e

85. SOLUTION 1 :
d
i. A completed sample AOA network
1
3
2
a
4
e
start
finish
b
c
f
g

86. ii. A completed sample AON network
SOLUTION 1 (CONTINUED):
a
b
e
start
finish
c
f
g
d

87. DRAW DIAGRAM USING NODES
The node have 3 part : NO., EST and LST
NO. – Event label / event number
EST – Earliest Start Time
LST – Latest Start Time
NO.
LST
EST

88. EXAMPLE 2 : DRAW NETWORK / DIAGRAM
4
18
7
11
19
33
20
20
20
20
36
36
31
31
5
2
6
9
3
8
7
F
A
G
K
E
D
10
J
L
4
15
7
12
9
5
H
6
11
1
0
0
8
8
4
B
8
3
C

89. EXAMPLE 3 : CRITICAL PATH
Find the critical path and critical time
Table 2
Task
Predecessor
Duration (days)
A
-
5
B
-
4
C
A
3
D
A
4
E
A
6
F
B, C
4
G
D
5
H
E
6
I
F
6
J
G, H
4

90. SOLUTION 3 : CRITICAL PATH
Critical path : A – E – H – J
Critical time : 21 days
21
1
0
0
5
5
8
11
12
15
21
9
12
4
2
14
17
7
8
11
6
10
3
11
11
5
9
D
A
E
F
B
C
4
I
5
4
4
6
4
H
3
6
6
J
17
17
8
5
G

91. FLOATS / SLACKS
Float (slack) - amount of time that a task can be delayed without causing a delay to:
subsequent tasks (free float)
project completion date (total float)
The slack of an event is the difference between the latest and earliest event times.
Slack = LST – EST
The events with zero slack time are known as critical events.
Example :
Slack event 5 = 17 – 7 = 10
Slack event 7 = 18 – 4 = 14
Slack event 9 = 17 – 17 = 0
Critical event / slack = 0 , so event 9 is critical event.
17
7
5
18
4
7
17
17
9

92. FLOAT / SLACKS (CONT.)
Total float is the spare time available on any given activity if the tail event occurred at its earliest time and the head event at its latest time.
Total float (TF) = Time latest at head – Time earliest
at tail – Activity duration
Example :
Total float activity B = 8 – 0 – 8 = 0 (Critical)
1
0
0
8
8
4
B
8

93. FLOAT / SLACKS (CONT.)
Free float is the spare time available on an activity if both the tail and the head events occurred at their earliest time. If this spare time is used up during the execution of this activity, it will have no effect on subsequent activities. It can be calculated thus :
Free float = Time earliest head – Time earliest
tail – activity duration
Example :
Free float activity B = 12 – 4 – 2 = 6
3
4
4
12
15
4
B
2

94. EXAMPLE 4 : FLOAT / SLACKS
The activities involved in a small project are given below along with relevant information. Construct the network , compute the critical path show the slack for each activity and find the floats for each activity .
Activity
Duration
1 – 2
20
1 – 3
25
2 – 3
10
2 – 4
12
3 – 4
6
4 – 5
10

95. SOLUTION 4 : FLOAT / SLACKS
The network diagram.
Critical path : B – E – F
0
0
46
46
20
20
2
1
36
36
4
30
30
3
A
C
B
10
5
25
10
E
20
12
F
6
D

96. SOLUTION 4 : FLOAT / SLACKS (CONT.)
The floats and slacks for each activity.
Activity
Duration
Earliest
Latest
Float
Slack
Start
Finish
Start
Finish
Total
Free
1 – 2
20
0
20
0
20
0
0
0 (Critical)
1 – 3
25
0
25
5
30
5
5
2 – 3
10
20
30
20
30
0
0
0 (Critical)
2 – 4
12
20
32
24
36
4
4
3 – 4
6
30
36
30
36
0
0
0 (Critical)
4 – 5
10
36
46
36
46
0
0
0 (Critical)

97. SOLUTION 4 : FLOAT / SLACKS (CONT.)
The slack for each activity.
Critical path : 1 – 2 – 3 – 4 – 5
Event
EST
LST
Slack
Remark
= (LST – EST)
1
0
0
0
Critical
2
20
20
0
Critical
3
30
30
0
Critical
4
36
36
0
Critical
5
46
46
0
Critical

98. EXERCISE :
Draw the network and compute the critical path.

99. SOLUTION :
13
8
F
7
7
13
13
C
A
16
16
G
f
c
2
3
g
6
3
h
5
7
3
10
3
6
13
D
B
9
16
E
d
2
e
3
3
h
18
18
H
0
0
START
a
b
e
Critical path: A – C – G – H
Total Completion Time: 7 + 6 + 3 + 2 = 18
Total slack: 4 + 7 + 7 + 8 = 26

100. THE END
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