plant Layout New

8/12/2019 plant Layout New

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PLANT LAYOUT

BBA-6

Lecture conducted by Apoorva Srivastava, ABS, AMITY, Lucknow


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LAYOUT

1.Define the meaning of layout planning the questions it addresses,

2.Describe the basic layout types and when each is best used,

3.Identify the types of performance criteria that are important inevaluating layouts.

4.Explain how cells can help create hybrid layouts,5.Recommend a step-by-step approach in designing process layouts.

6.Calculate load-distance scores for a process layout and explain howthis capability helps managers find a good solution.

7.Discuss different strategies in the layout of warehouses and offices.8. Describe how to balance lines in a product layout and evaluatedifferent solutions.


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What is Layout Planning ?

1.What centers should the layout include ?

2.How much space and capacity does each center need ?

3.How should each center space be configured ?

4.Where should each center be located ?


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IDENTICAL RELATIVE LOCATIONS AND DIFFERENT ABSOLTE

LOCATIONS

FROZEN

FOODS

BREAD

DRY GROCERIES

MEATS

VEGETABLES

ORIGINAL LAYOUT

DRY GROCERIES

FROZEN

FOODS

BREADVEGETABLES

MEATS

REVISED LAYOUT


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HOW SHOULD LAYOUT REFLECT

COMPETITIVE PRIORITIES ?

A Layout ought to reflect the following-

1.Facilitating the flow of materials and information.

2.Increasing the efficient utilization of labor and

equipment,3.Increasing customer convenience and sales at a

retail store,

4.Reducing hazards to workers,5.Improving employee morale,

6.Improving communications.


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VISHAL MEGA

MART

COLORFUL AND HIGH

ENERGY ATMOSPHERE

GLASS COLOR

MOSAICS,FULL

SPECTRUM DIGITAL

LIGHTING, LED SYSTEM

WALL MART

WIDE AISLES, LESS-CRAMPED

RACKS, SITTING AREAS FOR

CUSTOMERS, ATTRACTIVEDISPLAYS,

BARGAIN BASEMENT PRICES


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TYPES OF LAYOUT

PROCESS LAYOUT- with a job process, which is thebest for low volume, high variety production, theoperations manager must organize resources (employeesand equipment) around the process. A process layout,

which groups workstations or departments according tofunction, accompalish this purpose.

The process layout is most common when the sameoperation must intermittently produce many different

products or serve many different customers.

Demand levels are too low or unpredictable for managementto set aside human and capital resources exclusively for a

particular product line or type of customer.


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ADVANTAGES OF A PROCESS

LAYOUT OVER A PRODUCT

LAYOUT1.Resources are relatively general purpose and less capitalintensive.

2.The process layout is less vulnerable to changes in productmix or new marketing strategies and is therefore more

flexible.3.Equipment utilization is higher. When volumes are low,

dedicating resources to each product or service( as is donewith a product layout) would require more equipmentthan pooling the requirements for all product costs.

4.Employee supervision can be more specialized, animportant factor when job content requires a good deal oftechnical knowledge.


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DISADVANTAGES

1.Processing rates tend to be lower,

2.Productive time is lost in changing from one product or serviceto another,

3.More space and capital are tied up in inventory, which helps

workstations to work independently despite their variableoutput rates,

4.The time lags between job starts and end points are relativelylong,

5.Materials handling tends to be costly,6.Diversity in routings and jumbled flows necessitate the use of

variable path devices, such as carts rather than conveyors.

7.Production of planning and control is more difficult.


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PRODUCT LAYOUT

1.Processing rates tend to be slower.

2.Production time is lost in changing from one product or serviceto another,

3.More space and capital are tied up in inventory, which helps

workstations to work independently despite their variableoutput rates,

4.The time lags between job starts and end points are relativelylong,

5.Materials handling tends to be costly,6.Diversity in routings and jumbled flows necessitate the use of

variable path devices, such as carts rather than conveyors,

7.Production planning and control is more difficult.


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PRODUCT LAYOUT

1. With line or continuous processes, which are best for repetitiveor continuous production, the operations manager dedicatesresources to individual products or tasks. This strategy isachieved by Product Layout.

2. Resources are arranged around the products route, rather thanshared across many products.

3.Product Layouts are common in high-volume types ofoperations. Although product layouts often follow a straightline, a straight line is not always best, and layouts may take anL,O,S or U shape. A product layout often is called a production

line or an assembly line. The difference between the two is thatan assembly line is limited to assembly processes, whereas a

production line can be used to perform other processes such asprocesses such as machining.


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4.Product layouts often rely heavily on specialized,

capital intensive resources. When volumes are high,

the advantages of product layouts over process

layouts include-a).Faster processing rates,

b).Lower inventories,

c).Less unproductive time lost to changeovers andmaterials handling.


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There is less need to decouple one operation from the next,allowing management to cut inventories. The Japaneserefer to a line process as overlapped operations, wherebymaterials move directly from one operation to the next

without waiting in queues. The disadvantages of productlayouts include-

1.Greater risk of layout redesign for products or serviceswith short or uncertain lives,

2.Less flexibility,3.Low resource utilization for low volume products and

services.


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the challenge of product layout is to group activities into

workstations and achieve the desired output rate with

the least resources.


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HYBRID LAYOUT

1. More often than not, the process combines elements of both aproduct and portions of the facility are arranged in a process layoutand others are arranged in a product layout.

2. Hybrid layouts are used in facilities having both types of layout werein same building.

3. Fabrication operations- in which components are made from rawmaterials- have a jumbled flow, whereas assembly operations- inwhich components are assembled into finished products-have a lineflow.

4. Operations mangers also create hybrid layouts when introducingcells and flexible automation, such as Flexible ManufacturingSystem (FMS).

5. A cell is two or more dissimilar workstations located close togetherthrough which a limted number of parts or models are processedwith line flows.


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6.Two special types of Cells- Group Technology andOne Worker, Multiple Machines cells

7.An FMS is group of computer controlled workstations

at which materials are automatically handled andmachined loaded.

8.These technologies help achieve repeatability, even,when product volumes are too low to justify

dedicating a single line to one product, by bringingtogether all resources needed to make a family ofparts in one center. The rest of the facility represents aProcess Layout.


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A retail store is an example of a hybrid layout in a non-

manufacturing setting.


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FIXED POSITION LAYOUT

1.The product is fixed in place, workers, along with their tools

and equipment, come to the product to work on it.

2.Many project processes have this arrangement. This type of

layout makes sense when the product is particularly massiveor difficult to move, as in shipbuilding, assembling

locomotives , making huge pressure vessels, building dams,

or repairing home furnaces.

3.A fixed-position layout minimizes the number of times that

the product must be moved and often is the only feasible

solution.


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PERFORMANCE CRITERIA

1.level of capital investment,

2.Requirements for material handling,

3.Easy stockpiling,

4.Work environment and atmosphere,

5.Ease of equipment maintenance,

6.Employee attitudes,

7.Amount of flexibility needed,

8.Customer convenience and level of sales.


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CREATING HYBRID LAYOUTS

1.ONE WORKER MULTIPE MACHINES,

2.GROUP TECHNOLOGY.


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ONE WORKER, MULTIPLE MACHINES

1. The machines for production encircle the worker,

2. The operator would move around the cricle to perform tasks,that have not been automated.

3. An OWMM arrangement reduces both inventory and labor

requirements. Inventory is cut because, rather than piling upin queues, materials move directly into the next operation.

4. Different products or parts can be produced in an OWMMcell by consuming for one part, management can add aduplicate machine to the cell for use whenever that part is

being produced.

5. An OWMM arrangement both inventory and laborrequirements.


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6.Inventory is cut because, rather than piling up in queues,

materials move directly into the next operation. Labor is

cut because more work is automated.

7.The addition of 7 low cost automated devices canmaximize the number of machines included in an

OWMM arrangement: automatic tool changers, loaders

and unloaders, start and stop devices, and fail-safe

devices that detect defective parts or products. Japanesemanufacturers are applying the OWMM concept widely

because of their desire to achieve low inventories.


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MACHINE 1

MACHINE 2

MACHINE 3 MACHINE 4

MACHINE 5

MACHINE 6

ONE WORKER MULTIPLE MACHINES

CELL


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GROUP TECHNOLOGY

1.A second volume for achieving product layouts with

low volume processes is group technology(GT). This

manufacturing technique creates cells not limited to

just one worker or has a unique way of selecting workdone by the cell.

2.The GT Method group parts or products with similar

characteristics into families and set aside groups of

machines for their production. Families may be basedon size, shape, manufacturing or routing requirments,

or demand.


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3.The goal is to identify a set of products with similarprocessing requirements, or demand.

4. The goal is to identify a set of products with similarprocessing requirements and minimize machine

changeover or setup.5.Once parts have been grouped into families, the next

step is to organize the machine tools needed toperform the basic processes on these parts intoseparate cells.

6.The machines in each cell require only minoradjustments to accommodate product changeoversfrom one part to the next in the same family.


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7.By simplifying product routing, GT cells reduce

time a job is in shop. Queues of materials

waiting to be worked on are shortened or

eliminated.

8.Frequently, materials handling is automated so

that, after loading raw materials into the cell,

a worker does not handle machined partsuntil the job has been completed.


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RECEIVING AND SHIPPING

L

L

L

L

L

L

L

L

LATHING MILLING

M M

M M

M M

M M

DRILLING

D D

D D

G

GG

G

G G

GRINDING

ASSEMBLY

A A

A A


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DESIGNING PROCESS LAYOUT

The essence of designing a layout depends on whether aprocess layout or product layout has been chosen. Afixed-position format basically eliminate the layout

problem, whereas the design of the hybrid layout

partially uses the process-layout principles and partiallyuses product layout principles.

Process layout involves three basic steps, whether thedesign is for a new layout or for revising an existingone:

1.Gather information,2.Develop a block plan,

3.Design a detailed layout.


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Gather information

1.Space requirements by center- the layout designer must tie

space requirements to capacity plans, calculate the specific

equipment and space needs for each center, and allow

circulation space such as aisles and the like.

Block Plan- a plan that allocates space and indicates placement

of each department.


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Available Space

2.A Block Plan allocates space and indicates placement of eachdepartment. To describe a new facility layout, the plan need

only provide the facilitys dimensions and space allocations.

When an existing facility layout is being modified, the current

block plan is also needed.


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Closeness Factors

The layout designer must also know which centers need to be

located close to one another. Location is based on the number

of trips between centers and qualitative factors.

Trip Matrix- a matrix that gives the number of trips( or some

other measure of materials movement) between each pair of

the departments per day.

The designer estimates the number of trips between centers by

using routings and orderings frequencies for typical items made atthe plant, by carrying out statistical sampling, or by polling

supervisors and materials handlers. Only the right hand portion of

the matrix, which shows the number of trips in both directions, is

used.


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DEPARTMENT 1 2 3 4 5 6

1.Burr and

Grind

- 20 20 80

2.NC

Equipment

- 10 75

3.Shipping

and Receiving

- 15 90

4.Lathes and

drills

- 70

5.Tolls andcribs

-

6.Inspection -

TRIP MATRIX

TRIPS BETWEEN DEPARTMENTS


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Rel Chart

A chart that reflects the qualitative judgements of managers and

employees and that can be used in place of a Trip Matrix.

Rel is short for Relationships.

One advantage of of a REL chart is that the manager can account

for multiple performance criteria when selecting closeness

ratings, whereas, a trip matrix focuses solely on materials

handlings or stockpiling costs.


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RATING DEFINITION

A ABSOLUTELY NECESSARY

E ESPECIALLY IMPORTANT

I IMPORTANT

O ORDINARY CLOSENESS

U UNIMPORTANT

X UNDESIRABLE

CLOSENESS RATINGS


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CODE MEANING

1 MATERIALS HANDLING

2 SHARED PERSONAL

3 EASE OF SUPERVISION

4 SPACE UTILIZATION

5 NOISE

6 EMPLOYEE ATTITUDE

EXPLANATION CODES

Noise levels and management preference are potential sources ofperformance criteria that depend on absolute location. A REL chart

or Trip Matrix cannot reflect these criteria, because it reflects only

relative location considerations. The layout designer must list them

separately.


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DEPARTMENT 1 2 3 4 5 6

1.Burr and Grind - E(3,1)

U I(2,1)

U A(1)

2.NC Equipment - 0

(1)

U E

(1)

I

(6)

3.Shipping and receiving - O

(1)

U A

(1)4.Lathes and drills - E

(1)

X

(5)

5.Tool crib - U

6.Inspection -

CLOSENESS RATING BETWEEN DEPARTMENTS


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Step 2: Develop a Block Plan

The second step in layout design is to develop a block plan that

best satisfies performance criteria and area requirements. The

most elementary way to do so is by trial and error.

Because success depends on the designers ability to spot patterns

in the data, this approach does not guarantee the selection of

the best or even a nearly best solution. When supplemented by

the use of the a computer to evaluate solution, however, such

an approach often compares quite favorably with more

sophisticated computerized techniques.


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DEVELOPING A BLOCK PLAN

The goal is to minimize the materials handling costs.

Solution-

5 4 3

2 1 6

When relative locations are a primary concern, such as for effective

materials handling, stockpiling, and communication, the load-distancemethod can be used to compare alternative block plans. Here, Loads

are just the numbers in the Trip Matrix. Each Load goes between two

centers. The distance between two of them is calculated from the

block plan being evaluated. Of course, the loads need not be trips, anynumerical closeness measure related to distance would do.


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Calculating a Total Desirability Score

1.How much better, in terms of the ld score, is the proposed block plan? Use the Rectilinear Distance measure.

The accompanying table lists each pair of departments that has anonzero closeness factor in the trip matrix.

For the third column, calculate the rectilinear distance between the

departments in the current layout.Departments 1 and 2 are in the southeast and northwest blocks of the

plant, respectively.

The distance between the centers of these blocks is 3 units(twohorizontally and one vertically). For the fourth column, we multiplythe loads of distances and then add the results for a total of ld scoreof 785 for the current plan. Similar calculations for the proposed

plan produce and ld score of only 400. For example, betweendepartments 1 and 2 is just 1 unit of distance( one horizontally andone vertically).


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DEPARTME

NT PAIR

CLOSENESS

FACTOR,I

DISTANCE

d

LOAD-

DISTANCE

SOCRE,ld

DISTANCE

d

LOAD-DISTANCE

SCORE,ld

1,2 20 3 60 1 20

1,4 20 2 40 1 20

1,6 80 2 160 1 80

2,3 10 2 20 3 30

2,5 75 2 150 1 75

3,4 15 1 15 1 15

3,6 90 3 270 1 90

4,5 70 1 70 1 70ld = 785 ld = 400

CURRENT PLAN PROPOSED PLAN

To be exact, we could multiply the two ld scores by 30 because each unit of distance

represents 30 feet. However, relative differences between the two totals remains

unchanged.

SOLVER PROCESS LAYOUT


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DEPARTMENT PAIR

CLOSENESS FACTOR

DISTANCE SCORE

3,6 90 3 270

1,6 80 2 160

2,5 75 2 150

4,5 70 1 70

1,2 20 3 60

1,4 20 2 40

3,4 15 1 15

2,3 10 2 20

BUILD TABLE

SOLVER-PROCESS LAYOUT

RECTILINEAR EUCLIDEAN

2 4 1

6 5 3

TOTAL 785



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DEPARMENT CLOSENESS

FACTOR

DISTANCE SCORE

3,6 90 2 180

1,6 80 1 80

2,5 75 1 75

4,5 70 2 140

1,2 20 3 60

1,4 20 2 40

3,4 15 1 15

2,3 10 2 20

TOTAL 610


BUILD TABLE

RECTILINEAR DISTANCE

EUCLIDEAN DISTANCE

2 4 3

5 6 1


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DESIGN A DETAILED LAYOUT

After finding a satisfactory block plan, the layout designer into a

detailed representation, showing the exact size and shape of

each center, the arrangements of elements( e.g. desks,

machines, and storage areas), and the location of aisles,

stairways, and other service space. These visual representationcan be two-dimensional drawings, three-dimensional models,

or computer-aided graphics. This step helps decision makers

discuss the proposal and problems that might otherwise be

overlooked.


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AIDS FOR PROCESS LAYOUT

DECISIONSFinding an acceptable block plan actually is a complex process. A company

with 20 departments has 2.43*1018 possible layouts if each of the 20departments can be assigned to any of the 20 locations. Fortunately, severalcomputationally feasible aids are now available for helping managers make

process layout decisions.

ALDEP-Automated Layout Design Program- is a computer software packagethat uses REL chart information to construct a good layout. Being a heuristicmethod, it generally provides good, but not necessarily the best- solutions.ALDEP constructs a layout from scratch, adding one department at a time.The program picks the first department randomly. The second departmentmust have a strong REL rating with a department randomly. The second

department must have a strong rating with the second, and so on. When nodepartment has a strong rating with the department just added, the systemagain randomly selects the next department. The program computes a score(somewhat different from the ld score used earlier) for each solutiongenerated and print out the layouts having best scores for the managersconsideration.


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COMPUTERIZED RELATIVE ALLOCATION OF FACILITIES

TECHNIQUE- is a heuristic method that uses a Trip Matrix,

including materials flow rates, transportation costs, and an

initial block layout. Working from an initial block plan (or

starting solution), CRAFT evaluates all possible pairedexchanges of departments. The exchange that causes the

greatest reduction in the total ld score is incorporated into a

starting solution. The process continues until no other

exchanges can be found to reduce the ld score. The startingsolution at this point is also the final solution and is printed out

with the ld score.


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WAREHOUSE LAYOUTS

Warehouses are similar to manufacturing plants in that materialsare moved between activity centers.

LAYOUT SOLUTION- the decision rule is as follows-

1.Equal Areas- if all departments require the same space, simply

place one generating the most trips closest to the dock, the onegenerating the most trips closest to the dock, the onegenerating the next largest number of trips next closest to thedock, and so on.

2.Unequal Areas- if some departments need more space than

others, give the location closest to the dock to the departmentwith the largest ratio of the trip frequency to block location,and so on.


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Computer Software Systems

1.Computerised Relative Allocation of Facilities,

2.Computerised Facilities Design

3.Computerised Relationship Layout Planning

4.Automated Layout Design Program5.Plant Layout Analysis Evaluation Technique


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Performance Ratios

Storage Space Usage Ratio(SSUR)

= (Storage Space actually Occupied by materials

already used) / (Total square feet storage space

in facility)


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Inventory Turnover Ratio = (Annual sales in dollars)/

Average Inventory

Distance Travel Ratio = (total distance in feet orders

traveled during a specific planning horizon)/ (total

number of orders processed during the planning

horizon)

Damaged Goods Ratio = (number of damaged loads

moved during a specific planning horizon) / total

number of loads moved during the planning horizon


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Job Tardiness Ratio = (Number of jobs late during aspecific planning process) / total number of jobs

processed during the planning horizon

Order-Line Picking Ratio = (Number of lines( a line

represents an item) on orders picked during aspecific planning horizon) / (number of hoursworked by department personnel per day)

Receiving/ Shipping Ratio = Number of pounds( orpallets) shipped per day / Number of hours workedby department personnel per day


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Uses of Ratios

1.To see if layout performance can be improved by making

design changes and observing the results of the ratios.

2.To monitor layout performance to observe shifts in ongoing

operations.

3.To establish performance criteria that can be used as goals to

motivate improved performance.

USING TENG BLACK EXPERT


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USING TENG BLACK EXPERT

SYSTEM

The Teng Black Expert System or Delivery System comprises

three components: a knowledge base ( a set of rules in this

case to deal with known cellular problems), a working

memory ( a dynamic set of rules that shall change the

knowledge base a new problems are encountered in the cellsand solved), and the Inference Engine(a set of rules that

allows the system to reason, infer problems, and draw

conclusions on the control of cell behavior).

Electronics cells are positioned in the cells to provide feedbackon its operation against known or stated system parameters.


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Use of the Teng Black System

1. To control and monitor the cell operations,

2. To solve problems existing during the cells operation,

3. To communicate with higher-level human controllers( the cell

supervisor or plant manager)

STRUCTURE OF TENG-BLACK EXPERT SYSTEM


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MANAGEMENT

INTERFACINGLAYER

SIMULATIO

N

MODULE

HIGHER LEVELCONTROL UNITS

CELL

SUPERVISOR

PROBLEM

HANDLINGLAYER WORKING

MEMORY

KNOWLEDGE

BASE

INTERFACEENGINE

ROUTINE CELL

CONTROL LAYER

CELL

FLOW OF INFORMATION IN TENG BLACK EXPERT SYSTEM


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HIGH-LEVEL CONTROL

SYSTEM

CALL

CONTROL

SYSTEM

SIMULATION MODULE

SUPERVISOR

FLOW OF INFORMATION IN TENG BLACK EXPERT SYSTEM

SYSTEM

PARAMETERSSCHEDULE OF

FINAL

ASSEMBLY

CELL


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PRECEDENCE DIAGRAM

A diagram that allows one to visualize immediate predecessors

better; work elements are denoted by circles, with the time

required to perform the work shown below each circle.


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Desired Output Rate

The goal of the line balancing is to match the output rate to theproduction plan. For example, if the production plan calls for4,000 units per week and the line operates 80 hours per week,the desired output rate ideally would be 50 units (4000/80) perhour.

Matching output to demand ensures on-time delivery andprevents build-up of unwanted inventory.

However, managers should avoid rebalancing a line toofrequently, because each time a line is rebalanced, many

workers jobs on the line must be redesigned, temporarilyhurting productivity and sometimes even requiring a newdetailed layout for some stations.


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Desired Output Rate

Some automobile plants avoid frequent changes by eliminating a

shift entirely when demand falls and inventory becomes

excessive, rather than gradually scaling back the output rate.

Managers can also add shifts to increase equipment utilization,

which is crucial for capital-intensive facilties. However, higherpay rates or low demand may make multiple shifts undesirable

or unnecessary.


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Cycle Time

After determining a desired output rate for a line, the analyst cancalculate the lines cycle time.

A lines Cycle Time is the maximum time allowed for work on a unit ateach station. If the time required for work elements at a station

exceeds the lines cycle time, the station shall be the bottleneck,preventing the line from reaching its desired output rate. The targetcycle is the reciprocal of the desired hourly output rate- c = 1/ r

Where,

c= cycle time in hours per unit

r= desired output rate in units per hour

For example, if the lines desired output rate is 60 units per hour, thecycle time is c= 1/60 hour per unit , or 1 minute.


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Theoretical Minimum

To achieve the desired output rate, managers use line balancing to assign

every work element to a station, making sure to satisfy all precedence

requirements and to minimize the number of stations, n, formed.

If each station is operated by a different worker, minimizing n also

maximizes worker productivity.

Perfect Balance is achieved when the sum of the work-element times at

each station equals the cycle time, c, and no station has any idle time.

Although perfect balance usually is achievable in practice, owing to the

unevenness of work-element time and the inflexibility of precedencerequirements, it sets a benchmark, or goal, for the smallest number of

stations possible.


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The THEORETICAL MINIMUM( TM) for the number of stations is

TM = t / c

t = total time required to assemble each unit( the sum of all work-

element standard times)

C= cycle time.

For example, if the sum of the work element times is 15 minutes and thecycle time is 1 minute, TM=15/1, or 15 stations. Any fractional values

obtained for TM are rounded up because fractional stations are

impossible.

Idle Time Efficiency and Balance


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Idle Time, Efficiency, and Balance

Delay

Minimizing n automatically ensures (1) minimal idle time, (2)

maximal efficiency, and (3) minimal balance delay.

Idle time is the total unproductive time for all stations in the

assembly of each unit:

Where,

Idle time = nc -t

Where,

n = number of stations

c = cycle time

t= Total Standard Time Required to assemble each unit.


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Efficiency is the ratio of productive time to total time, expressed

as a percent:

Efficiency(percent) = t / nc(100)

Balance Delay is the amount by which efficiency falls short of

100 percent:

Balance delay(percent) = 100efficiency

As long as c is fixed, we can optimize all three goals by

minimizing n.


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CASE LET

Documents

plant Layout New