facility [mfrg

7/29/2019 Facility [Mfrg.

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Compiled by Prof. P.B.Owalekar

Facility Layout:Manufacturing and Services


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Overview

Introduction Manufacturing Facility Layouts

Analyzing Manufacturing Facility Layouts

Service Facility Layouts Wrap-Up: What World-Class Producers Do


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Introduction

Facility layout means planning: for the location of all machines, utilities, employee

workstations, customer service areas, material

storage areas, aisles, restrooms, lunchrooms,

internal walls, offices, and computer rooms

for the flow patterns of materials and people

around, into, and within buildings


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Locate All Areas In and Around Buildings

Equipment Work stations

Material storage

Rest/break areas Utilities

Eating areas

Aisles Offices


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Characteristics of the Facility Layout Decision

Location of these various areas impacts the flowthrough the system.

The layout can affect productivity and costs generated

by the system.

Layout alternatives are limited by

the amount and type of space required for the

various areas

the amount and type of space available

the operations strategy

. . . more


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Characteristics of the Facility Layout Decision

Layout decisions tend to be: Infrequent

Expensive to implement

Studied and evaluated extensively Long-term commitments


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Objectives of the Lay out Strategy

Develop an economical layout which will meet the

requirements of:

product design and volume (product strategy)

Process equipment and capacity (process strategy)

quality of work life (human resource strategy)

building and site constraints (location strategy)


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Requirements of a Good Layout

A good layout requires:

an understanding of capacity & space requirements

selection of appropriate material handling equipment

decisions regarding environment and aesthetics

identification and understanding of the requirements

for information flow

identification of the cost of moving between thevarious work areas


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Inputs to the Layout Decision

1. Specification of objectives of the system in terms ofoutput and flexibility.

2. Estimation of product or service demand on thesystem.

3. Processing requirements in terms of number ofoperations and amount of flow between departmentsand work centers.

4. Space requirements for the elements in the layout.

5. Space availability within the facility itself.


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Steps in Developing a Process Oriented Layout

Construct a from-to matrix

Determine space requirements for each department

Develop an initial schematic diagram

Determine the cost of this layout By trial-and error (or more sophisticated means), try to

improve the initial layout

Prepare a detailed plan that evaluates factors in

addition to transportation cost


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Warehouse & Storage Layout

General Cost Curve

0

20

40

60

80

100

120

10 20 30 40 50 60 70 80 90 100

Warehouse Density

Line 1

Line 2

Line 3The best warehouse layout is where

total costs are at a minimum

Material handling cost

(mostly variable)

Costs include:

Equipment

DamagePosition & Find

Investment

Material storage cost

(mostly fixed)

Costs include:

Land & building

Building & insurance


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Manufacturing Facility Layouts


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Basic Layout Forms

Process Product

Cellular

Fixed position Hybrid


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Process (Job Shop) Layouts

Equipment that perform similar processes aregrouped together

Used when the operations system must handle a wide

variety of products in relatively small volumes (i.e.,

flexibility is necessary)


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Characteristics of Process Layouts

General-purpose equipment is used Changeover is rapid

Material flow is intermittent

Material handling equipment is flexible Operators are highly skilled

. . . more


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Characteristics of Process Layouts

Technical supervision is required Planning, scheduling and controlling functions are

challenging

Production time is relatively long

In-process inventory is relatively high


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Product (Assembly Line) Layouts

Operations are arranged in the sequence required tomake the product

Used when the operations system must handle a

narrow variety of products in relatively high volumes

Operations and personnel are dedicated to producing

one or a small number of products


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Characteristics of Product Layouts

Special-purpose equipment are used Changeover is expensive and lengthy

Material flow approaches continuous

Material handling equipment is fixed Operators need not be as skilled

. . .more


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Characteristics of Product Layouts

Little direct supervision is required Planning, scheduling and controlling functions are

relatively straight-forward

Production time for a unit is relatively short

In-process inventory is relatively low


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Cellular Manufacturing (CM) Layouts

Operations required to produce a particular family(group) of parts are arranged in the sequence required

to make that family

Used when the operations system must handle a

moderate variety of products in moderate volumes


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Characteristics of CM

Relative to Process Layouts

Equipment can be less general-purpose Material handling costs are reduced

Training periods for operators are shortened

In-process inventory is lower Parts can be made faster and shipped more quickly


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Characteristics of CM

Relative to a Product Layout

Equipment can be less special-purpose Changeovers are simplified

Production is easier to automate


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Fixed-Position Layouts

Product remains in a fixed position, and thepersonnel, material and equipment come to it

Used when the product is very bulky, large, heavy or

fragile


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Hybrid Layouts

Actually, most manufacturing facilities use acombination of layout types.

An example of a hybrid layout is where departments

are arranged according to the types of processes but

the products flow through on a product layout.


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New Trends in Manufacturing Layouts

Designed for quality and flexibility Ability to quickly shift to different product models or

to different production rates

Cellular layout within larger process layouts

Automated material handling

U-shaped production lines

. . . more


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New Trends in Manufacturing Layouts

More open work areas with fewer walls, partitions, orother obstacles

Smaller and more compact factory layouts

Less space provided for storage of inventories

throughout the layout


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Process Layouts Product Layouts

Cellular Layouts

Analyzing Manufacturing Facility Layouts


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Process Layout

What factors might we consider when determiningthe locations of process areas, or departments?


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Designing and Analyzing a Process Layout

Group like processes together into departments orwork centers

Determine where in the building these departments

will be located relative to one another

The objective is to arrange the departments so that

some criterion such as material-handling cost is

minimized


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Approaches to Process Layout Design

Operations sequence analysis Block diagram analysis

Load-distance analysis

Computer analysis


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Operations Sequence Analysis

Inputs required an existing or proposed arrangement of

departments

a projection of the traffic or flow that will take

place between one department and each of the

other departments during some time period - this is

usually displayed as an interdepartmental flow

matrix . . .more


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Departments are represented by nodes (circles) Using the interdepartmental flow information, flows

between adjacent departments are represented by

solid lines. Dashed lines represent traffic between

nonadjacent departments. The projected volumes arewritten above the appropriate lines.

. . . more


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Departments (circles) are moved with the objective ofreducing the amount of nonadjacent flow.

This proceeds until no further improvement can be

found


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Block Diagram Analysis

This approach follows the operations sequenceanalysis and is an effort to make the solution more

realistic

Each department is represented by a square the

relative size of the department

Shapes of the squares are altered to fit into the

boundaries of the building while retaining the same

areas and relative position found in the operationssequence analysis


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Load-Distance Analysis

A way of quantitatively comparing alternativeprocess layouts

Inputs

Alternative block layouts which will provide the

distance between a department and each of the

other departments

For each product, the path it will follow (routing)

and its volume over some time period . . . more


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Load-Distance Analysis

For each alternative process layout, compute the totaldistance a product must travel using its routing

Compute the total distance traveled per time unit for

each product by multiplying its total travel distance

by its volume per time unit

Add the total distance traveled per time unit for each

product

Select the layout with the smallest sum


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Process Layout: Interdepartmental Flow

Given The flow (number of moves) to and from all

departments

The cost of moving from one department toanother

The existing or planned physical layout of theplant

Determine The best locations for each department, where

best means interdepartmental transportation, orflow, costs

Process Layout:


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Process Layout:

Cut-And-Try Approach

Involves searching for departmental changes toreduce overall flow cost

Difficult to determine correct moves

Non-optimal and based on limited criteria (cost, flow

and distance)

Process Layout:


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Process Layout:

Systematic Layout Planning

Numerical flow of items between departments Can be impractical to obtain

Does not account for the qualitative factors that

may be crucial to the placement decision

Systematic Layout Planning

Accounts for the importance of having each

department located next to every other department

Is also guided by trial and error

Switching departments then checking the results

of the closeness score

Example 1: Systematic Layout Planning


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Example 1: Systematic Layout PlanningReasons for Closeness

Code

1

2

3

4

5

6

Reason

Type of customer

Ease of supervision

Common personnel

Contact necessary

Share same price

Psychology



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Example 1: Systematic Layout PlanningImportance of Closeness

Value

A

E

I

O

U

X

ClosenessLine

code

Numerical

weights

Absolutely necessary

Especially important

Important

Ordinary closeness OK

Unimportant

Undesirable

16

8

4

2

0

80



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Example 1: Systematic Layout PlanningRelating Reasons and Importance

From

1. Credit department

2. Toy department

3. Wine department

4. Camera department

5. Candy department

6

I

--

U

4

A

--

U

--

U

1

I

1,6

A

--

U

1

X

1

X

To2 3 4 5

Area(sq. ft.)

100

400

300

100

100

Letter

Number

Closeness rating

Reason for rating



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Example 1: Systematic Layout PlanningThe Starting Solution

1

2

4

3

5

U U

E

A

I



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Example 1: Systematic Layout PlanningInitial and Final Layouts

1

2 4

3

5

Initial Layout

Ignoring space and

building constraints

2

5 1 4

3

50 ft

20 ft

Final Layout

Adjusted by square

footage and building

size


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Designing and Analyzing a Product Layout

Line Balancing


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Designing and Analyzing a Product Layout

Characteristics Inputs

Design Procedure

How Good Is The Layout?


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Product Layout-Advantages/Disadvantages

Advantages: Low cost variable cost per

unit

Lower material handling

costs reduction in work in-process

inventories

easier training and

supervision

Disadvantages: High volume required

because of large initial

investment

Work stoppage at any pointties up the whole process

Lack of flexibility in

handling variety of products

or production rates


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Line Balancing Problem

Work stations are arranged so that the output of one is

an input to the next, i.e., a series connection

Layout design involves assigning one or more of the

tasks required to make a product to work stations

. . . more


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The objective is to assign tasks to minimize theworkers idle time, therefore idle time costs, and meet

the required production rate for the line

In a perfectly balanced line, all workers would

complete their assigned tasks at the same time(assuming they start their work simultaneously)

This would result in no idle time

. . . more


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Unfortunately there are a number of conditions thatprevent the achievement of a perfectly balanced line

The estimated times for tasks

The precedence relationships for the tasks

The combinatorial nature of the problem


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Inputs

The production rate required from the product layoutor the cycle time.

The cycle time is the reciprocal of the production

rate and visa versa

All of the tasks required to make the product

It is assumed that these tasks can not be divided

further

. . . more


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Inputs

The estimated time to do each task The precedence relationships between the tasks

These relationships are determined by the technical

constraints imposed by the product

These relationships are displayed as a network

known as a precedence diagram

D i P d


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Design Procedure

1. If not provided, find the cycle time for the line.Remember the cycle time is the reciprocal of the

production rate. Make sure the cycle time is

expressed in the same time units as the estimated task

times.2. Select the line-balancing heuristic that may be used to

help with the assignments. (Two heuristics are

described at the end of this procedure.)

. . . more

D i P d


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Design Procedure

3. Open a new work station with the full cycle timeremaining.

4. Determine which tasks are feasible, i.e., can be

assigned to this work station at this time. For a task

to be feasible, two conditions must be met:

All tasks that precede that task must have already

been assigned

The estimated task time must be less than or equalto the remaining cycle time for that work station.

D i P d


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Design Procedure

5. If there are no feasible tasks, assignments to thatwork station are complete. Go back to step 3 (or stop,

if all tasks have been assigned).

If there is only one feasible task, assign it to the

work station. If there is more than one feasible task,use the heuristic (step 2) to determine which task to

assign. Reduce the work stations remaining cycle

time by the selected tasks time and return to step 4.

Li B l i H i ti


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Line-Balancing Heuristics

Heuristic methods, based on simple rules, have beenused to develop very good, not optimal, solutions to

line balancing problems.

Incremental Utilization Heuristic - adds tasks to a

workstation one at a time in the order of taskprecedence until utilization is 100% or is observed to

fall.

Longest-Task-Time Heuristic - adds tasks to a

workstation one at a time in the order of task

precedence, choosing - when a choice must be made -

the task with the longest time.

H G d I th D i ?


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How Good Is the Design?

Utilization is one way of objectively determining hownear perfectly balanced an assignment scheme is.

Utilization is the percentage of time that a production

line is working.

Utilization is calculated as:

or

100stations)workofnumber(ActualTime)(Cycle

stask timeallofSumx

x

100onsworkstatiofnumberActual

onsworkstatiofnumberMinimumx

P d t L t M j A ti


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Product Layouts-Major Assumptions

Volume is adequate for high equipment utilization. Product demand is stable enough to justify high

investment in specialized equipment.

Product is standardized or approaching a phase ofits life cycle that justifies investment in specialized

equipment.

Supplies of raw material and components are

adequate and of uniform quality to ensure they will

work with the specialized equipment.

Why is Balancing the Line Important?


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Station 1

Min/

Unit 6

Station 2

7

Station 3

3

Why is Balancing the Line Important?

Whats Going to Happen?


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Example 1: The ALB Problem

Youve just been assigned the job a setting up anelectric fan assembly line with the following tasks:

Task Time (Mins) Description Predecessors

A 2 Assemble frame NoneB 1 Mount switch A

C 3.25 Assemble motor housing None

D 1.2 Mount motor housing in frame A, C

E 0.5 Attach blade D

F 1 Assemble and attach safety grill EG 1 Attach cord B

H 1.4 Test F, G



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pThe Precedence Diagram

A

C

B

D E F

GH

2

3.25

1

1.2 .5

1

1.4

1

Which process step defines the maximum rate ofproduction?



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We want to assemble 100 fans per day

Required Cycle Time, C =Production time per period

Required output per period

C =420 mins / day

100 units / day= 4.2 mins / unit

What do these numbers this represent?



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We want to assemble 100 fans per day

Theoretical Min. Number of Workstations,N

N =Sum of task times (T)

Cycle time (C)

t

t

N =11.35 mins / unit

4.2 mins / unit= 2.702, or 3t

Why should we always round up?



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pSelected Task Selection Rules

Primary: Assign tasks in order the the largest numberof following tasks.

Secondary (tie-breaking): Assign tasks in order of thelongest operating time



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pSelected Task Selection Rules

Precedence Diagram

A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

Task Followers Time (Min)


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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1

Station 1 Station 2 Station 3

A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

B (2.2-1=1.2)

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A 6

2


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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

B (2.2-1=1.2)

G (1.2-1= .2)

Idle= .2

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A 6

2


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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

B (2.2-1=1.2)

G (1.2-1= .2)

Idle= .2

C (4.2-3.25)=.95

Idle = .95

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A 6

2


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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

B (2.2-1=1.2)

G (1.2-1= .2)

Idle= .2

C (4.2-3.25)=.95

Idle = .95

D (4.2-1.2)=3

Slide 71 of 96


A 6

2


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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

B (2.2-1=1.2)

G (1.2-1= .2)

Idle= .2

C (4.2-3.25)=.95

Idle = .95

D (4.2-1.2)=3

E (3-.5)=2.5

Slide 72 of 96


A 6

2


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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

B (2.2-1=1.2)

G (1.2-1= .2)

Idle= .2

C (4.2-3.25)=.95

Idle = .95

D (4.2-1.2)=3

E (3-.5)=2.5

F (2.5-1)=1.5

Slide 73 of 96


A 6

2


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A

C

B

D E F

GH

2

3.25

1

1.2 .5

11.4

1


A 6 2

C 4 3.25

D 3 1.2

B 2 1

E 2 0.5F 1 1

G 1 1

H 0 1.4

A (4.2-2=2.2)

B (2.2-1=1.2)

G (1.2-1= .2)

C (4.2-3.25)=.95 D (4.2-1.2)=3

E (3-.5)=2.5

F (2.5-1)=1.5H (1.5-1.4)=.1

Idle=.2 Idle=.95 Idle=.1

Slide 74 of 96



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Which station is the bottleneck? What is the effective cycle time?

Efficiency =Sum of task times (T)

Actual number of workstations (Na) x Cycle time (C)

Efficiency = 11.35 mins / unit(3)(4.2mins / unit)

=.901

Designing and Analyzing a Cellular Layout


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Designing and Analyzing a Cellular Layout

Fundamental questions: Which parts are going to be produced in a cell?

Which processes are going to be assigned to a cell?

Group Technology

B fit


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Benefits

1. Better human relations

2. Improved operator expertise

3. Less in-process inventory and material handling

4. Faster production setup

Fundamental Requirements


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for Parts to be Made in Cells

Demand for the parts must be high enough and stableenough that moderate batch sizes of the parts can be

produced periodically.

Parts must be capable of being grouped into parts

families.

Design Procedure


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Design Procedure

1. Form the Parts-Machines Matrix.

2. Rearrange the Rows.

Place the machines that produce the same parts in

adjacent rows.

3. Rearrange the Columns.

Place the parts requiring the same machines in

adjacent columns.

4. Using the rearranged parts-machines matrix toidentify cells, the machines for that cell and the parts

that will be produced in that cell.

Wrap-Up: World-Class Practice


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Wrap Up: World Class Practice

Strive for flexibility in layouts

Multi-job training of workers

Sophisticated preventive-maintenance programs

Flexible machines

Empowered workers trained in problem solving

Layouts small and compact

facility [mfrg

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