PLANT LAYOUTPlant layout refers to the arrangement of

physical facilities such as machinery, equipment, furniture etc. with in the factory building in such a manner so as to have quickest flow of material at the lowest cost and with the least amount of handling in processing the product from the receipt of material to the shipment of the finished product.

DEFINITIONAccording to Riggs, “the overall objective of

plant layout is to design a physical arrangement that most economically meets the required output – quantity and quality.”

 According to J. L. Zundi, “Plant layout ideally involves allocation of space and arrangement of equipment in such a manner that overall operating costs are minimized.

DETERMINENTS OF PLANT LAYOUT1. TYPE OF PRODUCT (size, shape and

quality)

2. TYPE OF PROCESS (technology employed, sequencing etc)

3. VOLUME OF PRODUCTIONS- (INCREASE OR DECREASE)

IMPORTANCE OF PLANT LAYOUT• It is long-term commitment• It facilitates the production process, minimizes

material handling, time and cost, and allows flexibility of operations

• It facilitates easy production flow, makes economic use of the building, promotes effective utilization of manpower, and provides for employee’s convenience, safety, comfort at work, maximum exposure to natural light and ventilation.

• it affects the flow of material and processes, labour efficiency, supervision and control, use of space and expansion possibilities .

OBJECTIVES OF PLANT LAYOUT• Proper and efficient utilization of available floor space • To ensure that work proceeds from one point to another point

without any delay • Provide enough production capacity• Reduce material handling costs • Reduce hazards to personnel • Utilize labour efficiently • Increase employee morale • Reduce accidents • Provide ease of supervision and control • Provide employee safety and health • Allow ease of maintenance • Allow high machine or equipment utilization • Improve productivity • To minimize cost of productions• Better inter department relationship

FACTORS INFLUENCING PLANT LAYOUT

1. Factory building :- The nature and size of the building determines the floor space available for layout. While designing the special requirements, e.g. air conditioning, dust control, humidity control etc. must be kept in mind.

2. Nature of product :- Product layout is suitable for uniform products whereas process layout is more appropriate for custom-made products.

3. Production process :- In assembly line industries, product layout is better. In job order or intermittent manufacturing on the other hand, process layout is desirable.

4. Type of machinery: General purpose machines are often arranged as per process layout while special purpose machines are arranged according to product layout.

5. Repairs and maintenance :- Machines should be so arranged that adequate space is available between them for movement of equipment and people required for repairing the machines.

6. Human needs :- Adequate arrangement should be made for cloakroom, washroom, lockers, drinking water, toilets and other employee facilities, proper provision should be made for disposal of effluents, if any.

7. Plant environment :- Heat, light, noise, ventilation and other aspects should be duly considered, e.g. paint shops and plating section should be located in another hall so that dangerous fumes can be removed through proper ventilation etc. Adequate safety arrangement should also be made.

8. Management policies :- management policies regarding size, quality, employee facilities and delivery schedules should be considered while deciding plant layout.

DYNAMICS OF PLANT LAYOUTIncrease in the output of the existing product Introduction of a new product and

diversification Technological advancements in machinery,

material, processes, product design, fuel etc. Deficiencies in the layout unnoticed by the

layout engineer in the beginning.

PRINCIPLES OF PLANT LAYOUT• PRINCIPLE OF MINIMUM MOVEMENT• PRINCIPLE OF FLOW• PRINCIPLE OF SPACE• PRINCIPLE OF SAFETY• PRINCIPLE OF FLEXIBILITY• PRINCIPLE OF INTERDEPENDENCE• PRINCIPLE OF OVERALL INTEGRATION• PRINCIPLE OF MINIMUM INVESTMENT

1. PRINCIPLE OF MINIMUM MOVEMENTAs far as possible materials and labour

should be moved over minimum distances.

2. PRINCIPLE OF FLOWThe work areas should be arranged

according to the sequence of operations so that there is continuous flow of materials without congestion.

The layout should allow for easy movement of materials without interruption or delay.

3. PRINCIPLE OF SPACEAll available cubic space should be effectively

used both vertically and horizontally.

4. PRINCIPLE OF SAFETYThere should be consideration for safety and

convenience of workers.There should be built in provision for the

safety and comfort.

5. PRINCIPLE OF FLEXIBILITYLayout should be designed in the manner

that production facilities can easily be rearranged when it becomes necessary in future on account of expansion and technological advancement.

6. PRINCIPLE OF INTERDEPENDENCEInterdependent operations and processes

should be located in close proximity to each other.

7.PRINCIPLE OF OVERALL INTEGRATIONAll the plant facilities and services should be

fully integrated into a single operating unit so as to maximize efficiency and minimize costs of production.

8. PRINCIPLE OF MINIMUM INVESTMENTThe layout should yield savings in fixed

capital investment through optimum utilization of available facilities.

TYPES OF LAYOUTS1. PRODUCT OR LINE LAYOUT2. PROCESS OR FUNCTIONAL LAYOUT3. FIXED POSITION OR LOCATION LAYOUT4. COMBINED OR GROUP LAYOUT

1.PRODUCT OR LINE LAYOUTUnder this, machines and equipments are

arranged in one line depending upon the sequence of operations required for the product. The materials move from 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)All the operations including assembly, testing, packing must be included in the line

ADVANTAGES OF PRODUCT LAYOUT

1. Low cost of material handling, due to straight and short route and absence of backtracking.

2. Smooth and uninterrupted operations 3. Continuous flow of work4. Lesser investment in inventory and work in progress 5. Optimum use of floor space6. Shorter processing time or quicker output 7. Less congestion of work in the process 8. Simple and effective inspection of work and

simplified production control 9. Lower cost of manufacturing per unit

DISADVANTAGES OF PRODUCT LAYOUT

1. High initial capital investment in special purpose machine

2. Heavy overhead charges 3. Breakdown of one machine will hamper the

whole production process 4. Lesser flexibility as specially laid out for

particular product.

SUITABILITY OF PRODUCT LAYOUT

1. Mass production of standardized products2. Simple and repetitive manufacturing process 3. Operation time for different process is more or less

equal 4. Reasonably stable demand for the product5. Continuous supply of materials Therefore, the manufacturing units involving

continuous manufacturing process, producing few standardized products continuously on the firm’s own specifications and in anticipation of sales would prefer product layout e.g. chemicals, sugar, paper, rubber, refineries, cement, automobiles, food processing and electronics etc.

2.PROCESS OR FUNCTIONAL 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.

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.

Used when the operations system must handle a wide variety of products in relatively small volumes (i.e., flexibility is necessary)

 The grouping of machines according to the process has to be done keeping in mind the following principles –  

1.The distance between departments should be as short as possible for avoiding long distance movement of materials.

2.The departments should be in sequence of operations

3.The arrangement should be convenient for inspection and supervision

ADVANTAGES OF PROCESS LAYOUT

1. Lower initial capital investment in machines and equipments. There is high degree of machine utilization, as a machine is not blocked for a single product

2. The overhead costs are relatively low

3. Change in output design and volume can be more easily adapted to the output of variety of products

4. Breakdown of one machine does not result in complete work stoppage

5. Supervision can be more effective and specialized

6. There is a greater flexibility of scope for expansion

DISADVANTAGES OF PROCESS LAYOUT

Material handling costs are high due to backtracking

More skilled labour is required resulting in higher cost.

Time gap or lag in production is higher Work in progress inventory is high needing

greater storage space More frequent inspection is needed which

results in costly supervision

SUITABILITY OF PROCESS LAYOUT

Products are not standardized Quantity produced is small There are frequent changes in design and style of

product Job shop type of work is done Machines are very expensive Thus, process layout or functional layout is suitable

for job order production involving non-repetitive processes and customer specifications and non-standardized products, e.g. tailoring, light and heavy engineering products, made to order furniture industries, jewelry.

3.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 center. This type of layout is not relevant for small scale entrepreneur.

E.g. - shipbuilding

ADAVANTAGES OF FIXED POSITION LAYOUT

1. It saves time and cost involved on the movement of work from one workstation to another.

2. The layout is flexible as change in job design and operation sequence can be easily incorporated.

3. It is more economical when several orders in different stages of progress are being executed simultaneously.

4. Adjustments can be made to meet shortage of materials or absence of workers by changing the sequence of operations.

 

DISADVANTAGES OF FIXED POSITION LAYOUT

Production period being very long, capital investment is very heavy

Very large space is required for storage of material and equipment near the product.

As several operations are often carried out simultaneously, there is possibility of confusion and conflicts among different workgroups.

SUITABILITY OF FIXED POSITION LAYOUTManufacture of bulky and heavy products

such as locomotives, ships, boilers, generators, wagon building, aircraft manufacturing, etc.

Construction of building, flyovers, dams.

4.COMBINED OR GROUP 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

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, 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.

RECENT TRENDS IN PLANT LAYOUT

Plant layout is the art and science of bringing to gather men, materials, methods and supporting facilities in the form of a given arrangements that suits individuals industrial activity to have the benefits of profits maximizations through economy, efficiency, effectiveness and productivity. The designing and instilling a layout is the responsibility of Engineering and planning department.  The process of preparing layout is an art and well as science.

The recent trends in layout are as follows – 1.The use of computerized facilities

design: The various techniques have

been developed and used in layout engineering such as ALDEP (Automated layout design program), CORELAP (Computerized relationship layout planning), CRAFT (computerized related allocation of facilities technique), CALP (computer Aided layout planning) etc. These and other programme can save time and effort in large and complex layout problems.

2.  The use of various tools and techniques for planning the layout –

Templates: It is a pattern which consists of thin plate of wood or metal which serves as gauge or guide in mechanical work. A plant layout template is a scaled representation of physical object in a layout.

Model equipment: Model or three dimensional models represents machinery installed in a factory. It is a replica or a miniature prototype of machine and equipment. These show minor details and can be mounted on a thick plastic sheet.

  Layout drawing: Layout drawings are the replica of a factory floor plan showing the space management. It is blue print which indicates the total square feet where all the equipment has to be arranged.

 Plot plan: Is a miniature of the entire factory building including the facilities of workers.

  Line balance: is phase of assembly line study that equally divides then works to be done among workers so that the total number of employees required is minimum. OR concepts like linear programming, dynamic programming and optimal methods are used to study line balance problem.

FACTORY BUILDINGA ideal plant building is the one which is built

to house the most efficient layout that can be provided for the process involved, and artificially attractive and of such standard shape and design which is flexible  its use and expansive units construction. The building ensures functional smoothness of the operation. It should be strong enough to withstand damages, vibrations and heavy machines.

FACTORS IN DESIGNING IN FACTORY BUILDINGAdaptability.Expandability.Product and equipment.Employees facilities and services areas.Materials handling.Lighting, ventilation and air-conditioning.Fire protection.Security and services and maintenance.

TYPES OF BUILDINGSThe decision on choosing a suitable type for a

particular firm depends among other things on the manufacturing process, the area of land, and the cost of construction. The industrial building can be grouped under four types –

1.Single storey building2.High bay and monitor types3.Multi-storey building4.Special building

Single storey building: The reduced cost of land and extensive transport facilities have encouraged single storey buildings in sub-urban areas.

High bay and monitor types: It is a single storey structures with roof surrounded by a monitor, giving maximum overhead space. The overhead space may be used to operate crane and other overhead facilities. The monitor provides natural ventilation and side walls with glass provide natural lighting.

Multi-storey building: In big cities costs of land is high and has no much scope of horizontal expansion which has given ways to multi-storey.

Special building: these are needed for certain manufacturing processes.  Eg the aircraft industry needs a building with spans 300 to 500 feet in length.

PLANT UTILITIESPlant utilities refer to such services as lighting,

ventilation, air-conditioning etc. All these deserve due consideration from operations management as they contribute to increased efficiency and greater output.

The types of plant facilities and services are as follow:

1.      Plant Lighting

2.      Ventilation

3.      Air-conditioning

4.      Industrial Sanitation

5.      Noise control

6.      Industrial safety

A. Plant lighting: Adequate lighting is necessary for a worker to perform his job with ease and accuracy. According to all India General Standards a minimum of 14 to 18 lumens of illuminations is considered adequate.

Importance of Good illumination: Ease of seeing./reduced eye strain, Improved quality of work. Better utilization of floor space. Good housekeeping. Fewer accidents. Improved employee morale/ better

supervision. Flexible layout.

There are two major source of lighting – 1.Day light2.Artificial light1. Day light - It is natural lighting which is

received from the sun.2. Artificial light – It refers to illumination

through artificial means as bulbs and tubes.Types of artificial lights are –

a. General lighting - General lighting is provided by fixtures, luminaries or grid system placed 10 ft above the work area. The light is provided uniformly over the whole department in a sufficient intensity to satisfy the requirement of the general manufacturing conditions within it.

b. Supplementary lighting – It involves the provision

of intense light at the point of work or in adjacent areas to suit the worker particular requirement.

TYPES OF LIGHT SOURCES – 1.  Filament or incandescent lamps.2.  Discharge lamps or fluorescent lamps.3.  Electro-luminescent lamps, mercury

vapor lamps.

B. VENTILATION – Ventilation is concerned largely

with engineering techniques for controlling air currents within the plant and for introducing outdoor air in a pattern and on a scale that is just adequate to maintain satisfactory air purity.

Importance of ventilation are –Protection of the health of workers. Preservation of quality of the productMeets legal requirement.

TYPES OF VENTILATION1.General ventilation – To keep the working conditions at acceptable

comforts level.To keep contaminants in the air within safe

limits.

2.General exhaust ventilation – It is a system for

preventing the contamination of factory air by withdrawing the contaminant at its source into a duct system for discharge to the building exterior.

SOURCES OF VENTILATION 1.NATURAL VENTILATION2.MECHANICAL VENTILATION

C. AIR CONDITIONING - Industrial air-conditioning requires control over temperatures, humidity, dust, purity and odors.

Objectives of air-conditioning1.  To protect worker’s health.2. To improve workers comfort level.3. To secure specified temperature conditions.4. To improve the quality of products.5. Product preservations.6. To reduce maintenance charges.7. To improve employer-employee relations.

D. INDUSTRIAL SANITATION - Sanitation refers to

control of the spread of infection and other insults to the health of the employees.  Occupational disease caused by the industrial process leads to employee’s dissatisfaction and turnover.

OBJECTIVES – Supply of portable water.Disposal of waste and effluents.Provision of food which is free from

contamination.Elimination of insects and rodents.Provision of personal services.Good housekeeping.

E. NOISE CONTROL -Noise is unwanted and unpleasant sound.

Elements –Impairs the hearing of employees.Results in fatigue and nervousness.Vibration causes damage to machinery and

equipments.Bad working environmentNoise control methods – Control by absorptionControl at sourceControl by ear protection 

BREAK EVEN ANALYSISIt is easy to understand that decision of site

selection is an economic one. The site that offers least cost of operations should be the one selected for implementation. Total operation cost can be classified in two broad categories.

- Fixed Costs - Variable Costs.

Where Total Cost can be split up into Fixed & Variable Cost ,it is easy to prepare the BEP as it would facilitate for optimal decisions by taking into account volume of business

BEP are drawn for different locations to compare the sites. Fixed Costs, Variable Costs & Revenue / Output are taken into account to do so. Mathematically,

BE Volume: FC /Contribution.

FACTOR RATING METHODFactor-rating systems are perhaps the most widely used of the

general location techniques because they provide a mechanism to combine diverse factors in an easy-to-understand format.

Popular because a wide variety of factors can be included in the Popular because a wide variety of factors can be included in the analysisanalysis

Six steps in the methodSix steps in the method

1.1. Develop a list of relevant factors called critical success Develop a list of relevant factors called critical success factorsfactors

2.2. Assign a weight to each factorAssign a weight to each factor

3.3. Develop a scale for each factorDevelop a scale for each factor

4.4. Score each location for each factorScore each location for each factor

5.5. Multiply score by weights for each factor for each locationMultiply score by weights for each factor for each location

6.6. Recommend the location with the highest point scoreRecommend the location with the highest point score

Finds location of distribution center that Finds location of distribution center that minimizes distribution costsminimizes distribution costs

ConsidersConsiders Location of marketsLocation of markets Volume of goods shipped to those marketsVolume of goods shipped to those markets Shipping cost (or distance)Shipping cost (or distance)

CENTER OF GRAVITY METHOD

Place existing locations on a Place existing locations on a coordinate gridcoordinate grid Grid origin and scale is arbitrary Grid origin and scale is arbitrary

Maintain relative distancesMaintain relative distances Calculate X and Y coordinates for Calculate X and Y coordinates for

‘center of gravity’‘center of gravity’ Assumes cost is directly proportional Assumes cost is directly proportional

to distance and volume shippedto distance and volume shipped

x - coordinate =x - coordinate =∑∑ddixixQQii

∑∑QQii

ii

ii

∑∑ddiyiyQQii

∑∑QQii

ii

ii

y - coordinate =y - coordinate =

BROWN & GIBSON METHODThe Brown–Gibson model is one of the

many techniques for multi-attribute decision making. The method was developed in 1972 by P. Brown and D. Gibson. This is one of the few models which integrates both objective and subjective factors in decision making.

The Brown–Gibson model can be mathematically represented as follows –

Mi = Ci X [D X Oi + (1−D) X Si]

Where,M = Measure for an alternative 'i'C = Critical factor measure which could be either

be 0 or 1 for an alternative 'i'O = Objective factor measure which could be

between 0 and 1 however the sum of all objective factor measures for different alternatives should add back to 1

S = Subjective factor measure which could be between 0 and 1 however the sum of all subjective factor measures for different alternatives should add back to 1

D = Objective factor decision weight and this should be between 0 and 1

We would select the alternative whose measure is the highest.