1 deliverables of design review 1 statement of problem/need customer needs product design...

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DELIVERABLES OF DESIGN REVIEW 1

Statement of problem/need

Customer needs

Product Design Specifications (PDS)

Design targets

Project plan

TOOLS USED TO PRODUCE THOSE DELIVERABLES

Customers research

QFD

Gantt’s chart

CPM (if applicable)

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PLANNING THE DESIGN PROJECT IN MME259a

Design review 1

Design review 2

Design review 3

Final report

Gantt’s chart should be updated by actual project progress (here in red)

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CRITICAL PATH METHOD (CPM)

Complex projects tasks require a series of activities, some of which must be

performed sequentially and other can be performed in parallel with other activities.

The collection of series and parallel tasks can be modeled as a network.

The Critical Path Method (CPM) was developed in 1957 as a network model for

project managements. CPS is a deterministic method using a fixed time estimate for

each activity.

The Critical Path Method - is a project planning technique used to determine the most

efficient sequence of tasks.

A modification of CPM is PERT (Program Evaluation and Review Technique) which

takes into consideration that tasks duration may vary.

http://hadm.sph.sc.edu/COURSES/J716/CPM/CPM.html

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In a project, an activity is a task that must be performed and an event is a milestone marking the completion of one or more activities. Before an activity can begin, all of its predecessor activities must be completed.

The milestone can be numbered so that the ending node of an activity has a higher number the beginning node. It is convenient to increment the numbers by 10 so that new nodes may be easily inserted.

The activities are labeled with letters along with the expected time required to complete the activity.

MILESTONE

Node 40 (labeled as number)

event marking completion of an

activity

TASK

Activity E (labeled as letter)

Duration 3 weeks

CRITICAL PATH METHOD (CPM)

5

A

3

CRITICAL PATH METHOD (CPM)

Primary elements of a CPM diagram :

Activity - is a time consuming effort that is required to perform part of the project (a task). An activity is represented by an arrow.

Event - is a point of accomplishment and/or decision (i.e. a milestone). It marks the end of one activity and the beginning of another. An event is represented by a circle.

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RULE 2. An event cannot be reached (a task can not be completed) until all activities leading to it are complete.

Activities F and G must both be completed before activity H can begin.

Logic restrictions to constructing CPM diagrams:

RULE 1. An activity cannot be started until its tail event is reached

Activities D and E cannot begin until activity C has been completed.

CD

E

1

HF

G

2

CRITICAL PATH METHOD (CPM)

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Activity A must precede both B and C

– B must precede D and E

– C must precede E

– D and E must precede F

– Note: Dummy activities show a sequential connection but no expenditure of time.

RULE 3. Sometimes an event is dependent on another event preceding it, even though the two events are not linked together by an activity.

0

2

1 3

54

A

D

E

F

B

C

CRITICAL PATH METHOD (CPM)

Logic restrictions to constructing CPM diagrams:

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Example:

The CPM network shown below for constructing a building implies that the window frames can be installed before the walls are built (an illogical situation).

By adding a dummy activity, the network now indicates that the installation of window frames has to await both the fabrication of the window frames and the building of the walls.

0

10

20

30

Build WallsConstruct Roof

Make Window Frames Install Window Frames

0

10

20

30

Build WallsConstruct Roof

Make Window Frames Install Window Frames

20 20

4 2

CRITICAL PATH METHOD (CPM)

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Basic parameters for time estimates :

ES - Earliest Start Time The earliest time that an activity can begin when all preceding activities are completed as rapidly as possible.

LS - Latest Start TimeThe latest time that an activity can be initiated without delaying the minimum completion time for the project.

EF - Earliest Finish Time EF = ES + D where D is the duration of each activity.

LF - Latest Finish Time LF = LS + D

.TF - Total Float Time (slack)TF = LS – ES

Note: An activity on the critical path has zero total float TF = 0

CRITICAL PATH METHOD (CPM)

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ES = 4

node 50:

B, E ES = 6

A, D ES = 5

A, C, F ES = 7

ES = 3

ES = 4

Calculation of early start times ES based on CPM diagram.

ES times are determined by starting at the first event (node) and making a forward pass through the network while adding each activity duration to the ES of the preceding activity.

CRITICAL PATH METHOD (CPM)

ES for the last activity actually means the end of project

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ES = 4

ES = 3

ES = 4

CRITICAL PATH METHOD (CPM)

Calculation of late start LS times based on CPM diagram.

LS times are calculated by starting at the last event (node) and a backward pass is made through the network while subtracting the activity duration from the limiting LS at each event

LS = 5

LS = 3

LS = 4

ES = 7

12

ES = 4

ES = 7ES = 3

ES = 4

CRITICAL PATH METHOD (CPM)

An activity on the critical path has zero total float (slack)

TF = LS – ES = 0

LS = 5

LS = 3

LS = 4

SLACK = 1

SLACK = 0 SLACK = 0

CRITICAL PATH

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Gantt chart for testing a heat exchanger.

Activities for testing a heat exchanger.

Example: Prototype testing of heat exchanger.

CRITICAL PATH METHOD (CPM) – EXAMPLE 1

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STEP 1 Perform forward pass to determine ES for each activity

ES times are determined by starting at the first event (node) and making a forward pass through the network while adding each activity duration in turn to the ES of the preceding activity.

3

13

12

16 18 20

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Example: Prototype testing of heat exchanger.

CRITICAL PATH METHOD (CPM) – EXAMPLE 1

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STEP 2 Perform backward pass to determine LS for each activity

LS times are calculated by starting at the last event (node) and a backward pass is made through the network while subtracting the activity duration from the limiting LS at each event

16

18 – 2 = 16

18

20 – 2 = 18

20

12

16-3=13

13

16 – 3 = 13

Example: Prototype testing of heat exchanger.

713 – 5 = 813 – 6 = 7

3

13 - 3 = 10

7- 4 = 3LIMITING LS

LIMITING LS

I

CRITICAL PATH METHOD (CPM) – EXAMPLE 1

16

16

18 – 2 = 16

18

20 – 2 = 18

20

12

16-3=13

13

16 – 3 = 13

Example: Prototype testing of heat exchanger.

713 – 5 = 813 – 6 = 7

3

13 - 3 = 10

7- 4 = 3LIMITING LS

LIMITING LS

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STEP 3 Find critical path

Critical path is where TF = 0

CRITICAL PATH METHOD (CPM) – EXAMPLE 1

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Example: Prototype testing of heat exchanger.

Summary of boundary timetable.

CRITICAL PATH METHOD (CPM) – EXAMPLE 1

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CRITICAL PATH METHOD (CPM)

ES is determined by forward pass through network

LS is determined by backward pass through network

Time float TF = LS – ES

Path where TF = 0 is the CRITICAL PATH

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3

2 2

12

4

1

2

2

10

20

30

40

5060

70 80

CRITICAL PATH METHOD (CPM) – EXAMPLE 2

20

3

2 2

12

4

1

2

2

10

20

30

40

5060

70 80

3

?

5

?

8

?5

?

9

?1

?3

?

5

?

Forward pass to determine ES

7

?

CRITICAL PATH METHOD (CPM) – EXAMPLE 2

21

3

2 2

12

4

1

2

2

10

20

30

40

5060

70 80

36 - 2 = 45 - 2 = 3

5

8 – 2 = 6

8

5

9 – 4 = 5

9

9

1

7 – 2 = 5

3

9 – 2 = 7

5

Backward pass to determine LS

7

9 – 1 = 8

CRITICAL PATH METHOD (CPM) – EXAMPLE 2

22

3

2 2

12

4

1

2

2

10

20

30

40

5060

70 80

36 - 2 = 45 - 2 = 3

5

8 – 2 = 6

8

5

9 – 4 = 5

1

7 – 2 = 5

3

9 – 2 = 7

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The critical path where we must not allow any delayor else the final event will not be reached in 9 weeks

7

9 – 1 = 8

9

9

CRITICAL PATH METHOD (CPM) – EXAMPLE 2

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Activity Description Time estimate, weeks

Preceded by

A Product design 5 none

B Market research 1 none

C Production analysis 2 A

D Product model 3 A

E Sales brochure 2 A

F Cost analysis 3 C

G Product testing 4 D

H Sales training 2 B, E

I Pricing 1 H

J Project report 3 F, G, I

EX 1.The various activities associated with developing a new product are summarized below.

(i) Draw a CPM network diagram for completing the above activities in the proper sequence

(ii) Determine the critical path by calculating ES, LS, EF, LF and TF

CRITICAL PATH METHOD (CPM) – EXAMPLE 3

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1

2

3

5

4 7 8

6

A(5)

B(1)

E(2)

H(2) I(1)

F(3)

C(2)

D(3)

G(4)

J(3)

Productdesign

A5

MarketResearch

B1

ProductionAnalysis

C2

ProductModel

D3

CostAnalysis

F3

Producttesting

G4

Salesbrochure

E2

Salestraining

H2

Pricing

I1

Projectreport

J3

CRITICAL PATH METHOD (CPM) – EXAMPLE 3

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1

2

3

5

4 7 8

6

A(5)

B(1)

E(2)

H(2) I(1)

F(3)

C(2)

D(3)

G(4)

J(3)

1512

9

7

7

8

5

0

Forward pass to determine ES

CRITICAL PATH METHOD (CPM) – EXAMPLE 3

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1

2

3

5

4 7 8

6

A(5)

B(1)

E(2)

H(2) I(1)

F(3)

C(2)

D(3)

G(4)

J(3)

1515-3=12

12-1=11

11-2=9

12-3=9

12-4=8

8-3=5

1512

9

7

7

5

0

8

Backward pass to determine LS

CRITICAL PATH METHOD (CPM) – EXAMPLE 3

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Activity Description D ES LS EF LF TF

A Product design 5 0 0 5 5 0

B Market research 1 0 8 1 9 8

C Production analysis

2 5 7 7 9 2

D Product model 3 5 5 8 8 0

E Sales brochure 2 5 7 7 9 2

F Cost analysis 3 7 9 10 12 2

G Product testing 4 8 8 12 12 0

H Sales training 2 7 9 9 11 2

I Pricing 1 9 11 10 12 2

J Project report 3 12 12 15 15 0

D = Duration (weeks)

ES = Earliest Start

LS = Latest Start

EF = Earliest finish (ES + D)

LF = Latest finish (LS + D)

TF = Total float time (LS-ES)

CRITICAL PATH METHOD (CPM) – EXAMPLE 3

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1

2

3

5

4 7 8

6

A(5)

B(1)

E(2)

H(2) I(1)

F(3)

C(2)

D(3)

G(4)

J(3)

Total Project duration = 15 weeks

CRITICAL PATH METHOD (CPM) – EXAMPLE 3

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Activity Description Time estimate, weeks

Preceded by

A Investigation and planning 5 none

B Customer feedback 2 none

C Define the market 1 none

D Initial concept design 4 A

E Concept Selection 3 B

F System modeling 2 B, C, E

G Detail Design 3 B, C, E

H Initial Prototype 3 B

I Testing 3 A, D

J Final Prototype 2 A, D

K Production 1 G, H, I

L Establish product cost 2 F

CRITICAL PATH METHOD (CPM) – EXAMPLE 4

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1

3

4

5

8

7

6

2

CRITICAL PATH METHOD (CPM) – EXAMPLE 4

Investigation

and planning A5

Customer

feedback

B2

Define the market C1

Initial concept

Design D4

Concept SelectionE3

System modelingF2

Detail Design

H3

Detail Design

G3

TestingI3

Final Prototype

J2

ProductionK1

Establish product costL2

31

13

4

5

8

7

A(5)

B(2)

E(3)

H(3)

I(3)

F(2)

D(4)

G(3)

J(2)

C(1)

6

2

K(1)

L(2)

13

5

2

5 7

9

12

CRITICAL PATH METHOD (CPM) – EXAMPLE 4

Forward pass to determine ES

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13

4

5

8

7

A(5)

B(2)

E(3)

H(3)

I(3)

F(2)

D(4)

G(3)

J(2)

C(1)

6

2

K(1)

L(2)

13

5

9

9 11

LS=9

12

CRITICAL PATH METHOD (CPM) – EXAMPLE 4

Backward pass to determine LS

13

5

2

5 7

9

12

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Activity Description D ES LS EF LF TF

A Investigation and planning 5 0 0 5 5 0

B Customer feedback 2 0 4 2 6 4

C Define the market 1 0 8 1 9 8

D Initial concept design 4 5 5 9 9 0

E Concept Selection 3 2 6 5 9 4

F System modeling 2 5 9 7 11 4

G Detail Design 3 5 9 8 12 4

H Initial Prototype 3 2 9 5 11 9

I Testing 3 9 9 12 12 0

J Final Prototype 2 9 11 11 13 2

K Production 1 12 12 13 13 0

L Establish product cost 2 7 11 9 13 4

CRITICAL PATH METHOD (CPM) – EXAMPLE 4

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13

4

5

8

7

A(5)

B(2)

E(3)

H(3)

I(3)

F(2)

D(4)

G(3)

J(2)

C(1)

6

2

K(1)

L(2)

Total Project duration = 13 weeks