9-1 operations management layout strategy chapter 9

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Operations Operations ManagementManagement

Layout StrategyLayout StrategyChapter 9Chapter 9

9-2

OutlineOutline

Strategic Importance of Layout Decisions.

Fixed-Position Layout.

Office Layout.

Process-Oriented Layout (Flow graphs).

Retail Layout.

Warehouse Layout.

Product-Oriented Layout (Assembly line balancing).

9-3

What is Facility LayoutWhat is Facility Layout Location or arrangement of everything

within & around buildings.

Objectives are to maximize: Utilization of space, equipment, & people.

Efficient flow of information, material, & people.

Employee morale & safety.

Trend is towards flexible and dynamic layouts.

9-4

Facility LayoutFacility Layout

Helps achieve competitive advantage:

Better, faster, cheaper.

Determines productivity, cost, quality, flexibility, image, etc.

May involve a blend of strategies.

9-5

Six Layout StrategiesSix Layout Strategies

1. Fixed-position layout. For large unique projects such as ships and buildings.

2. Office layout. Positions workers, equipment, and spaces/offices to

provide for movement of information and material.

3. Process-oriented layout. For low-volume, high-variety production.

9-6

Six Layout Strategies - continuedSix Layout Strategies - continued

4. Retail/service layout. Arranges facility and allocates shelf space in light of

customer behavior.

5. Warehouse layout. Addresses trade-offs between space utilization and

material handling.

6. Product-oriented layout. For repetitive or continuous production.

9-7

Layout StrategiesLayout Strategies

Project(fixed-position)

Job Shop(Process-oriented) Office

Examples

Problem

Ingal Ship Building

Pittsburgh Airport

Shouldice Hospital

Olive Garden

Allstate Insurance

Microsoft

Move material to limited

storage areas at the site.

Manage varied material flow for

each product.

Locate workers requiring contact

close to each other.

9-8

Layout StrategiesLayout Strategies

RetailWarehouse

(storage)

Repetitive/Continuous

(Product-oriented)

Examples

Problem

Kroger’s Supermarket

Famous-Barr

Federal-Mogul’s Warehouse

The Gap’s distribution center

Sony’s TV Assembly Line

Dodge Caravans

Expose customer to high-margin

items.

Balance cost for storage and

material handling.

Equalize the task time at

each workstation.

9-9

Requirements for a Good LayoutRequirements for a Good Layout

Understand capacity and space requirements.

Understand information flows.

Understand cost of people and product flows.

Select appropriate material handling equipment.

Consider environment and aesthetics.

Consider safety and regulations.

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Constraints on Layout ObjectivesConstraints on Layout Objectives

Product/service design.

Volume of business.

Process equipment & capacity.

Quality of work life.

Building and site.

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1. Fixed-Position Layout1. Fixed-Position Layout

Project is stationary. Special purpose: Construction, shipbuilding, etc.

Workers and equipment come to site.

Complicating factors. Limited space at site.

Changing material needs.

Unique projects.

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2. Office Layout2. Office Layout Positions people, equipment, & offices.

Usually for maximum information flow.

Also can consider material flow.

Arranged by process or product. Example: Payroll dept. is by process.

Different cultures have different expectations for space.

Relationship (or proximity) chart used.

9-13

Relationship (Proximity) ChartRelationship (Proximity) Chart Uses 6 levels to express desired proximity.

A = Absolutely necessary

E = Especially important

I = Important

O= Ordinary importance

U = Unimportant

X = Not desirable

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Relationship (Proximity) ChartRelationship (Proximity) Chart

1 PresidentO

2 Costing UE A

3 Engineering IU

4 President’s Secretary

5 Photocopiers

UE

A

X

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Relationship (Proximity) ChartRelationship (Proximity) Chart

1 PresidentO

2 Costing UE A

3 Engineering IU

4 President’s Secretary

5 Photocopiers

UE

A

X

1

4

3

2

5A

A

E

E

I

X

Can determine layout using proximity diagram

9-16

Office LayoutOffice Layout1 President

O2 Costing U

E A3 Engineering I

U4 President’s Secretary

5 Photocopiers

UE

A

X

1

4

3

2

5A

A

E

E

I

X

Locate 5 offices in a rectangular space.

Offices 2-5 are to be same size.

Office 1 (President’s) is twice as large.

9-17

Office LayoutOffice Layout

Costing(3)

Photocopiers (5)

President’sSecretary

(4)

(2)

President (1)

Engineering

Corridor

9-18

3. Process-Oriented Layout3. Process-Oriented Layout

Place departments with large flows of material or people close together.

Similar processes and equipment are located in close proximity. For example, all x-ray machines in same area.

Used with process-focused processes. Low volume, high variety.

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Emergency Room LayoutEmergency Room LayoutSurg

ery

RadiologyE.R. beds Pharmacy Billing/exit

E.R.Triage room

E.R. AdmissionsPatient B - erratic pacemaker

Patient A - broken leg

Hallway

9-20

Process-Oriented Layout AdvantagesProcess-Oriented Layout Advantages

Flexibility. Allows wide variety of products.

Low fixed costs for general purpose equipment.

Breakdown of one machine or worker does not stop processing.

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Process-Oriented Layout Process-Oriented Layout DisadvantagesDisadvantages

Scheduling is difficult.

High variable cost.

High work-in-process inventory and waiting.

High labor skills required.

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Developing a Process-Oriented Developing a Process-Oriented Layout by HandLayout by Hand

Goal: Minimize cost of moving between departments.

1 Construct a “from-to matrix”.

2 Determine space requirements for each department.

3 Develop an initial layout and try to place departments with large flows close together.

4 Determine the cost of this initial layout.

5 Improve the initial layout (by hand or more sophisticated means).

6 Consider factors in addition to transportation cost.

9-23

Cost of Process-Oriented LayoutCost of Process-Oriented Layout

jiij

C

jiij

X

i,j

n

ijC

ijX

n

i

n

j

department and department between load a move tocost

department to department from moved loads of number

sdepartment individual

sdepartment or centers workof number total where

cost Minimize

1 1

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1 2 3 4 5 6

1

2

3

4

5

6

40 100 0 0 0

10 40 10 0

0 0 80

50 0

0

10

0

0

0

20

20

10

0

0

20

0

2000 0

Flows of Parts (loads/week)Flows of Parts (loads/week)fr

om

to

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Interdepartmental Flow of PartsInterdepartmental Flow of Parts

1 2 3 4 5 6

1

2

3

4

5

6

50 100 0 0 20

30 50 10 0

20 0 100

50 0

0

Number of loads/week between departments

9-26

Initial LayoutInitial Layout

AssemblyDepartment

(1)

PrintingDepartment

(2)

Machine shopDepartment

(3)

ReceivingDepartment

(4)

ShippingDepartment

(5)

TestingDepartment

(6)

Room 1 Room 2 Room 3

Room 4 Room 5 Room 6

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Initial Layout Flow Graph Initial Layout Flow Graph Showing Loads/WeekShowing Loads/Week

100

50 30

1020

50

20

10050

1 2

4 5 6

3

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Cost of Initial LayoutCost of Initial Layout

100

50 30

1020

50

20

10050

1 2

4 5 6

3

1-2 50 = 50*11-3 200 = 100*21-6 40 = 20*22-3 30 = 30*12-4 50 = 50*12-5 10 = 10*13-4 40 = 20*23-6 100 = 100*14-5 50 = 50*1Total = $570

Cost per load for adjacent locations = $1Cost per load for non-adjacent locations = $2

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Large Flows in Initial LayoutLarge Flows in Initial Layout100

50 30

1020

50

20

10050

1 2

4 5 6

3

Largest Flows: 100 for 1-3 & 3-6, so put 3 close to 1 and 6.

50 for 1-2, 2-4 & 4-5 ,

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Improved Layout Flow GraphImproved Layout Flow Graph

100

10050

30

10

20

50

2050

2

4

31

5 6

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Improved LayoutImproved Layout

PrintingDepartment

(2)

AssemblyDepartment

(1)

Machine shopDepartment

(3)

ReceivingDepartment

(4)

ShippingDepartment

(5)

TestingDepartment

(6)

Room 1 Room 2 Room 3

Room 4 Room 5 Room 6

9-32

Cost of Improved LayoutCost of Improved Layout

1-2 50 = 50*11-3 100 = 100*11-6 20 = 20*12-3 60 = 30*22-4 50 = 50*12-5 10 = 10*13-4 40 = 20*23-6 100 = 100*14-5 50 = 50*1Total = $480

Cost per load for adjacent locations = $1Cost per load for non-adjacent locations = $2

10050

30

10

20

50

2050

2

4

31

5 6

100

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Alternative Improved LayoutAlternative Improved Layout

50

100100

20

20

50

30

50

1

2

63

4 5

10

9-34

Cost of Alternative Improved LayoutCost of Alternative Improved Layout

1-2 50 = 50*11-3 100 = 100*11-6 40 = 20*22-3 30 = 30*12-4 50 = 50*12-5 20 = 10*23-4 20 = 20*13-6 100 = 100*14-5 50 = 50*1Total = $460

Cost per load for adjacent locations = $1Cost per load for non-adjacent locations = $2

50

100100

20

20

50

30

50

1

2

63

4 5

10

Is this best?

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Alternative Improved LayoutAlternative Improved Layout

PrintingDepartment

(2)

AssemblyDepartment

(1)

Machine shopDepartment

(3)

ReceivingDepartment

(4)

ShippingDepartment

(5)

TestingDepartment

(6)

Room 1 Room 2 Room 3

Room 4 Room 5 Room 6

9-36

Layout Example 2Layout Example 2Given the following tables of interdepartmental flows and distances between locations A-E, locate the five departments to minimize the total distancexflow.

Interdepartmental flows

1 2 3 4 5

1 - 13 18 3 02 - 15 0 6

3 - 0 4

4 - 4

A B C D E

A - 9 8 12 14B 9 - 9 6 7

C 8 9 - 4 9

D 12 6 4 - 14

Distances between locations

E 14 7 9 14 -

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Layout Example 2Layout Example 2Largest flow 1-3 (flow=18) should be in closest locations: C&DCould have: Solution 1: C=1 and D=3 or Solution 2: C=3 and D=1

Interdepartmental flows

1 2 3 4 5

1 - 13 18 3 02 - 15 0 6

3 - 0 4

4 - 4

A B C D E

A - 9 8 12 14B 9 - 9 6 7

C 8 9 - 4 9

D 12 6 4 - 14

Distances between locations

E 14 7 9 14 -

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Layout Example 2Layout Example 2Next largest flow is 2-3, so 2 should be placed in location closest to 3. Solution 1: D=3 and closest open location to D is B, so B=2, C=1, D=3. Solution 2: C=3 and closest open location to C is A, so A=2, C=3, D=1.

Interdepartmental flows

1 2 3 4 5

1 - 13 18 3 02 - 15 0 6

3 - 0 4

4 - 4

A B C D E

A - 9 8 12 14B 9 - 9 6 7

C 8 9 - 4 9

D 12 6 4 - 14

Distances between locations

E 14 7 9 14 -

9-39

Layout Example 2Layout Example 2Next largest flow is 1-2, but 1 and 2 are already located.So consider next largest flow 2-5.Solution 1: B=2 and closest open location to B is E, so A=4,B=2,C=1, D=3,E=5. Solution 2: A=2 and closest open location to A is B, so A=2,B=5,C=3, D=1,E=4.

Interdepartmental flows

1 2 3 4 5

1 - 13 18 3 02 - 15 0 6

3 - 0 4

4 - 4

A B C D E

A - 9 8 12 14B 9 - 9 6 7

C 8 9 - 4 9

D 12 6 4 - 14

Distances between locations

E 14 7 9 14 -

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Layout Example 2Layout Example 2Solution 1: A=4,B=2,C=1, D=3,E=5. Distance = 13x9 + 18x4 + 3x8 + 15x6 + 6x7 + 4x14 + 4x14 = 457 Solution 2: A=2,B=5,C=3, D=1,E=4.Distance = 13x12 + 18x4 + 3x14 + 15x8 + 6x9 + 4x9 + 4x7 = 508

Interdepartmental flows

1 2 3 4 5

1 - 13 18 3 02 - 15 0 6

3 - 0 4

4 - 4

A B C D E

A - 9 8 12 14B 9 - 9 6 7

C 8 9 - 4 9

D 12 6 4 - 14

Distances between locations

E 14 7 9 14 -

Solution 1 is best!

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Computer Programs for LayoutComputer Programs for Layout

Many different programs: CRAFT SPACECRAFT CRAFT 3-D CORELAP ALDEP

All are heuristic - not necessarily optimal!!

9-42

Work Cells in Process LayoutsWork Cells in Process Layouts

Special case of product-oriented layout - in a process-oriented facility. Different machines brought together to make a product.

Use when high volume warrants special arrangement.

For 1 product or a small group of products.

Temporary arrangement.

Example: Assembly line set up to produce 3000 identical parts in a job shop.

9-43

Work Cell Floor PlanWork Cell Floor Plan

OfficeOffice

Tool RoomTool RoomWork CellWork Cell

SawsSaws DrillsDrills

9-44

Work Cell AdvantagesWork Cell Advantages

Lower:

Inventory.

Floor space.

Direct labor costs.

Higher:

Equipment utilization.

Employee participation.

Quality.

9-45

Work Cells, Focused Work Work Cells, Focused Work Centers and the Focused FactoryCenters and the Focused Factory

Work Cell A temporary assembly-line-oriented arrangement of machines and personnel in what is ordinarily a process-oriented facility.

Focused WorkCenter

A permanent assembly-line-oriented arrangement of machines and personnel in what is ordinarily a process-oriented facility.

Focused Factory A permanent facility to produce a product or component in a product-oriented facility.

9-46

4. Retail/Service Layout4. Retail/Service Layout

Maximize product exposure to customers. Maximize profitability per square foot of floor space or

per linear foot of shelf space.

Decision variables: Arrangement of store.

Store flow pattern.

Allocation of (shelf) space to products.

Video

9-47

Retail Layouts - Rules of ThumbRetail Layouts - Rules of Thumb Locate high-draw items around the periphery.

Use prominent locations (end aisle locations; first or last aisle) for high-impulse and high margin items.

Remove crossover aisles to prevent customers from moving between aisles.

Distribute “power items” (that dominate a shopping trip) around store to increase the viewing of other items. Locate far apart.

Locate on both sides of an aisle.

9-48

Grocery Store LayoutGrocery Store Layout

9-49

Retail Store Shelf SpaceRetail Store Shelf Space

Consider prominence of shelf location and number of facings.

Can use computerized tools to manage shelf-space.

Track sales and product location (scanner data).

55 facingsfacings

PE

RT

PE

RT

PE

RT

PE

RT

PE

RT

9-50

Servicescape ConsiderationsServicescape Considerations

Ambient conditions. Background characteristics such as lighting, sound,

smell, and temperature.

Spatial layout and functionality. Customer circulation, aisle width, shelf spacing, etc.

Signs, Symbols, and Artifacts. Various other characteristics of design (carpeting,

greeters, etc.).

9-51

5. Warehouse Layout5. Warehouse Layout Balance space utilization & handling cost.

Similar to process layout.

Items moved between loading docks & various storage areas.

Optimum layout depends on: Variety of items stored.

Number of items picked.

9-52

Space Utilization vs. Handling Space Utilization vs. Handling Costs Costs

High space utilization (for storage). Small, narrow aisles.

Product stacked high and deep (not easily accessible).

Ease of material handling. Wide, short aisles.

Product easily accessible.

Design facility to optimize space utilization and handling costs tradeoff.

9-53

Assigned vs. Random Stock Assigned vs. Random Stock LocationsLocations

Assigned locations for products: May be inefficient use of space. Easier order picking and re-stocking.

Random locations: More efficient use of space. Added costs to track location of inventory and “open” space. More difficult order picking and re-stocking.

Stock products to optimize cost and efficiencies tradeoffs.

9-54

Cross Docking (Wal-Mart)Cross Docking (Wal-Mart) Transferring goods:

From incoming trucks at receiving docks.

To outgoing trucks at shipping docks.

Avoids placing goods into storage.

Requires suppliers provide effective addressing (bar codes) and packaging for rapid transshipment.

In-In-comingcoming

OutgoingOutgoing

9-55

Order PickingOrder PickingCollecting items on a customer order from various

locations in the warehouse.

Sequence items to minimize travel time in warehouse to pick order. Also, should locate items to be efficient to pick.

Combine several orders to reduce picking time.

Zoning: Assign separate pickers to different zones in the warehouse. Split order among several pickers.

9-56

6. Product-Oriented Layout6. Product-Oriented Layout Used with product-focussed processes.

Facility organized around product.

High volume, low variety.

Types: Fabrication line - Builds components.

Assembly line - Assembles components into products.

9-57

Product-Oriented LayoutProduct-Oriented Layout Divide work into small tasks. To be done by

workers or machines.

Assign tasks to workstations.

Balance output of each workstation. To smooth operations of the line.

To make workload equal.

To minimize idle time.

To achieve desired output.

9-58

Product-Oriented RequirementsProduct-Oriented Requirements

Standardized product.

High production volume.

Stable production quantities.

Uniform quality of raw materials & components.

9-59

Product-Oriented Layout AdvantagesProduct-Oriented Layout Advantages

Lower variable cost per unit.

Lower material handling costs.

Lower work-in-process inventories.

Rapid throughput.

Easier training & supervision.

9-60

Product-Oriented Layout Product-Oriented Layout DisadvantagesDisadvantages

Higher capital investment for special equipment.

Any work stoppage stops whole process.

Lack of flexibility in volume and product.

9-61

Repetitive LayoutRepetitive Layout

Note: Note: 5 tasks or operations (T1-T5);5 tasks or operations (T1-T5); 3 work stations (orange rectangles)3 work stations (orange rectangles)

T1 T3

T2

T4

T5

Work Station 1Work Station 1

OfficeOffice

Belt ConveyorBelt Conveyor

Work Work Station 3Station 3

Work Station 2Work Station 2

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Assembly Line Balancing StepsAssembly Line Balancing Steps

1. Determine tasks (operations) & task times.

2. Determine sequence of tasks.

3. Draw precedence diagram.

4. Calculate cycle time .

5. Calculate minimum number of work stations, N.

6. Assign tasks.

7. Calculate efficiency.

9-63

Assembly Line Balancing DataAssembly Line Balancing Data

Usually we are given:

Production rate. Units of product to be produced per unit time.

Production time available per day.

Tasks (operations) & task times.

Sequence of tasks.

9-64

Assembly Line BalancingAssembly Line BalancingGeneral ProcedureGeneral Procedure

1. Determine cycle time - The time between production of successive units. (May be measured in seconds, minutes, etc.)

2. Calculate the theoretical minimum number of workstations, denoted N. (May not be achievable.)

3. Assign tasks to workstations to “balance” the line. Compute the efficiency.

9-65

Assembly Line Balancing EquationsAssembly Line Balancing Equations

Cycle time = Production time available

Production rate

Minimum number of work stations

Task times

Cycle time

Efficiency =

=

Task times

* (Cycle time)(Actual number of work stations)

= N Rounded up

9-66

Assembly Line Balancing ExampleAssembly Line Balancing Example

Task Time Predecessor A 0.1 min. - B 0.7 min. A C 1.0 min. B D 0.5 min. C E 0.2 min. D

2.5 min.

Immediate

A B C D E

0.1 0.20.7 1.0 0.5

Suppose we want to produce 300 units/day and 8 hours are available each day.

9-67

Assembly Line Balancing ExampleAssembly Line Balancing Example

Task Time Predecessor A 0.1 min. - B 0.7 min. A C 1.0 min. B D 0.5 min. C E 0.2 min. D

2.5 min.

Immediate Suppose we want to produce 300 units/day and 8 hours are available each day.

nsworkstatioortesminu

tesminuN

unittesminudayunits

daytesminutimecycle

25625.16.1

5.2

/6.1/300

/480

So assign tasks A-E to 2 workstations, where neither workstation should exceed 1.6 minutes.

9-68

Assembly Line Balancing ExampleAssembly Line Balancing Example

A B C D E

0.1 0.20.7 1.0 0.5

Suppose we want to produce 300 units/day and 8 hours are available each day.

Can not use only 2 workstations! Must use 3.

Efficiency=2.5/(3*1.6) = 52.1%

Task Time Predecessor A 0.1 min. - B 0.7 min. A C 1.0 min. B D 0.5 min. C E 0.2 min. D

2.5 min.

Immediate

9-69

Assembly Line Balancing ExampleAssembly Line Balancing Example

A B C D E

0.1 0.20.7 1.0 0.5

Both of these can produce 300/day in 8 hours.

Efficiency=2.5/(3*1.6) = 52.1%

A B C D E

0.1 0.20.7 1.0 0.5

Efficiency=2.5/(3*1.6) = 52.1%

Better balance!

Note: this line could produce 300 units in 5 hours (1 per minute) Efficiency=2.5/(3*1.0) = 83.3%

9-70

Assembly Line Balancing ExampleAssembly Line Balancing Example

A B C D E

0.1 0.20.7 1.0 0.5

If 2 workstations were required, then it will take more than 8 hours to produce 300 units.

Cycle time = 1.7 minutes

Efficiency=2.5/(2*1.7) = 73.5%

Time to produce 300 units

1.7 min/unit*300 units = 510 minutes = 8.5 hours

9-71

Assembly Line Balancing HeuristicsAssembly Line Balancing Heuristics

Longest (or shortest) task time. Choose task with longest (or shortest) operation time.

Most following tasks. Choose task with largest number of following tasks.

Ranked positional weight. Choose task where the sum of the times for each following

task is longest.

Least number of following tasks. Choose task with fewest subsequent tasks.

9-72

Ranked Positional Weight HeuristicRanked Positional Weight Heuristic

Positional weight = Sum of times for a task and all tasks that must follow it.

1. Calculate positional weight for each task.

2. Assign task with largest positional weight to the earliest workstation where it fits.- Obey precedence relations.- Do not exceed cycle time.

3. Repeat step 2 until all tasks are assigned.

9-73

Line Balancing Example 2Line Balancing Example 2

Task Time Predecessor A 0.2 min. - B 0.6 min. A,C C 0.5 min. - D 0.3 min. - E 1.0 min. B,D F 0.2 min. D G 0.9 min. E,F

3.7 min.

Immediate

Suppose we want to produce 450 units/day and 8 hours are available each day.

9-74

Line Balancing Example 2Line Balancing Example 2

Task Time Predecessor A 0.2 min. - B 0.6 min. A,C C 0.5 min. - D 0.3 min. - E 1.0 min. B,D F 0.2 min. D G 0.9 min. E,F

3.7 min.

Immediate

Suppose we want to produce 450 units/day and 8 hours are available each day.

nsworkstatioortesminu

tesminuN

unittesminudayunits

daytesminutimecycle

4...47.30667.1

7.3

/0667.1/450

/480

9-75

AB

EC

DF

G

0.2

Precedence Diagram - Example 2Precedence Diagram - Example 2

0.5

0.3

0.6

0.2

1.00.9

9-76

Example 2 - Positional WeightExample 2 - Positional Weight

Task Time Predecessor weight A 0.2 min. - 2.7 B 0.6 min. A,C 2.5 C 0.5 min. - 3.0 D 0.3 min. - 2.4 E 1.0 min. B,D 1.9 F 0.2 min. D 1.1 G 0.9 min. E,F 0.9

3.7 min.

Immediate Positional

9-77

Example 2 - Assign TasksExample 2 - Assign Tasks

Task Time Predecessor weight A 0.2 min. - 2.7 B 0.6 min. A,C 2.5 C 0.5 min. - 3.0 D 0.3 min. - 2.4 E 1.0 min. B,D 1.9 F 0.2 min. D 1.1 G 0.9 min. E,F 0.9

3.7 min.

Immediate Positional

Cycle time = 1.07 min.

N = 4 workstations

WS1 WS2 WS3 WS4 C(0.5)

A(0.2)

9-78

Example 2 - Assign Tasks (cont.)Example 2 - Assign Tasks (cont.)

Task Time Predecessor weight A 0.2 min. - 2.7 B 0.6 min. A,C 2.5 C 0.5 min. - 3.0 D 0.3 min. - 2.4 E 1.0 min. B,D 1.9 F 0.2 min. D 1.1 G 0.9 min. E,F 0.9

3.7 min.

Immediate Positional

Cycle time = 1.07 min.

N = 4 workstations

WS1 WS2 WS3 WS4 C(0.5) B(0.6)

A(0.2)

D(0.3)

9-79

Example 2 - Assign Tasks (cont.)Example 2 - Assign Tasks (cont.)

Task Time Predecessor weight A 0.2 min. - 2.7 B 0.6 min. A,C 2.5 C 0.5 min. - 3.0 D 0.3 min. - 2.4 E 1.0 min. B,D 1.9 F 0.2 min. D 1.1 G 0.9 min. E,F 0.9

3.7 min.

Immediate Positional

Cycle time = 1.07 min.

N = 4 workstations

WS1 WS2 WS3 WS4 C(0.5) B(0.6) E(1.0) G(0.9)

A(0.2) F(0.2)

D(0.3)

Efficiency = 3.7/(4*1.07) = 86.4%

9-80

AB

EC

DF

G

0.2

Precedence Diagram - Example 2Precedence Diagram - Example 2

0.5

0.3

0.6

0.2

1.00.9

WS1 WS2

WS3

WS4

9-81

Example 2 - Final CommentExample 2 - Final Comment

Task Time Predecessor A 0.2 min. - B 0.6 min. A,C C 0.5 min. - D 0.3 min. - E 1.0 min. B,D F 0.2 min. D G 0.9 min. E,F

3.7 min.

Immediate

Could use a cycle time of 1 minute & produce 450 units in 7.5 hours

WS1 WS2 WS3 WS4 C(0.5) B(0.6) E(1.0) G(0.9)

A(0.2) F(0.2)

D(0.3)

Efficiency = 3.7/(4*1.0) = 92.5%