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Effect of Design Quality on Manufacturing Cost [Ull97, p.3]

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Title: Effect of Design Quality on Manufacturing Cost [Ull97, p.3] Author: Engineering Last modified by: Paul Kurowski Created Date: 12/6/2000 12:49:31 PM – PowerPoint PPT presentation

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Title: Effect of Design Quality on Manufacturing Cost [Ull97, p.3]


1
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 Gantts
chart CPM (if applicable)
2
PLANNING THE DESIGN PROJECT IN MME259a
Final report
Design review 1
Design review 2
Design review 3
Gantts chart should be updated by actual project
progress (here in red)
3
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
4
CRITICAL PATH METHOD (CPM)
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
5
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.
A
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.
6
CRITICAL PATH METHOD (CPM)
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.
D
C
1
E
  • 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.

F
H
2
G
7
CRITICAL PATH METHOD (CPM)
Logic restrictions to constructing CPM diagrams
RULE 3. Sometimes an event is dependent on
another event preceding it, even though the two
events are not linked together by an activity.
  • 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.

8
CRITICAL PATH METHOD (CPM)
9
CRITICAL PATH METHOD (CPM)
  • 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 Time
  • The 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

10
CRITICAL PATH METHOD (CPM)
ES 4
ES for the last activity actually means the end
of project
ES 3
node 50 B, E ES 6 A, D ES 5 A, C, F ES 7
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.
11
CRITICAL PATH METHOD (CPM)
ES 4
LS 4
ES 3
ES 7
LS 3
ES 4
LS 5
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
12
CRITICAL PATH METHOD (CPM)
SLACK 0
ES 4
SLACK 0
LS 4
ES 3
ES 7
LS 3
ES 4
LS 5
CRITICAL PATH
SLACK 1
An activity on the critical path has zero total
float (slack) TF LS ES 0
13
CRITICAL PATH METHOD (CPM) EXAMPLE 1
Gantt chart for testing a heat exchanger.
Activities for testing a heat exchanger.
Example Prototype testing of heat exchanger.
14
CRITICAL PATH METHOD (CPM) EXAMPLE 1
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.
12
7
3
Example Prototype testing of heat exchanger.
13
16
18
20
15
CRITICAL PATH METHOD (CPM) EXAMPLE 1
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
12 16-313
7 13 5 8 13 6 7
LIMITING LS
3 13 - 3 10 7- 4 3
I
LIMITING LS
Example Prototype testing of heat exchanger.
16 18 2 16
18 20 2 18
20
13 16 3 13
16
CRITICAL PATH METHOD (CPM) EXAMPLE 1
STEP 3 Find critical path Critical path is
where TF 0
12 16-313
7 13 5 8 13 6 7
LIMITING LS
3 13 - 3 10 7- 4 3
I
LIMITING LS
Example Prototype testing of heat exchanger.
16 18 2 16
18 20 2 18
20
13 16 3 13
17
CRITICAL PATH METHOD (CPM) EXAMPLE 1
Summary of boundary timetable.
Example Prototype testing of heat exchanger.
18
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
19
CRITICAL PATH METHOD (CPM) EXAMPLE 2
2
2
30
20
40
1
2
3
4
50
60
10
1
2
2
70
80
20
CRITICAL PATH METHOD (CPM) EXAMPLE 2
5 ?
3 ?
7 ?
2
2
30
8 ?
20
40
1
2
5 ?
3
4
9 ?
50
60
10
1
1 ?
5 ?
3 ?
2
2
70
80
Forward pass to determine ES
21
CRITICAL PATH METHOD (CPM) EXAMPLE 2
5 8 2 6
7 9 1 8
3 6 - 2 4 5 - 2 3
2
2
30
8
20
40
1
2
5 9 4 5
3
4
9 9
50
60
10
1
5
1 7 2 5
3 9 2 7
2
2
70
80
Backward pass to determine LS
22
CRITICAL PATH METHOD (CPM) EXAMPLE 2
5 8 2 6
7 9 1 8
3 6 - 2 4 5 - 2 3
2
2
30
8
20
40
1
2
5 9 4 5
3
4
9 9
50
60
10
1
5
1 7 2 5
3 9 2 7
2
2
70
80
The critical path where we must not allow any
delay or else the final event will not be reached
in 9 weeks
23
CRITICAL PATH METHOD (CPM) EXAMPLE 3
  • EX 1.The various activities associated with
    developing a new product are summarized below.
  • Draw a CPM network diagram for completing the
    above activities in the proper sequence
  • Determine the critical path by calculating ES,
    LS, EF, LF and TF

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
24
CRITICAL PATH METHOD (CPM) EXAMPLE 3
Product Model D3
Product testing G4
Product design A5
Production Analysis C2
Sales brochure E2
Cost Analysis F3
Project report J3
Market Research B1
Pricing I1
Sales training H2
25
CRITICAL PATH METHOD (CPM) EXAMPLE 3
5
8
D(3)
5
G(4)
2
A(5)
C(2)
4
F(3)
7
J(3)
8
E(2)
0
1
15
7
12
3
B(1)
I(1)
H(2)
7
6
9
Forward pass to determine ES
26
CRITICAL PATH METHOD (CPM) EXAMPLE 3
8
5
12-48
D(3)
5
8-35
G(4)
2
A(5)
C(2)
4
F(3)
0
7
J(3)
8
E(2)
1
15
12
7
15
15-312
12-39
3
B(1)
I(1)
7
H(2)
11-29
6
9
12-111
Backward pass to determine LS
27
CRITICAL PATH METHOD (CPM) EXAMPLE 3
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)
28
CRITICAL PATH METHOD (CPM) EXAMPLE 3
5
D(3)
G(4)
2
A(5)
C(2)
4
F(3)
7
J(3)
8
E(2)
1
3
B(1)
I(1)
H(2)
6
Total Project duration 15 weeks
29
CRITICAL PATH METHOD (CPM) EXAMPLE 4
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
30
CRITICAL PATH METHOD (CPM) EXAMPLE 4
5
Initial concept Design D4
2
Final Prototype J2
Testing I3
Investigation and planning A5
6
Production K1
3
8
Customer feedback B2
Detail Design H3
1
Detail Design G3
Concept Selection E3
Define the market C1
7
4
Establish product cost L2
System modeling F2
31
CRITICAL PATH METHOD (CPM) EXAMPLE 4
9
5
D(4)
5
2
J(2)
I(3)
A(5)
6
H(3)
K(1)
3
8
B(2)
1
2
12
E(3)
G(3)
13
C(1)
7
L(2)
4
F(2)
5
7
Forward pass to determine ES
32
CRITICAL PATH METHOD (CPM) EXAMPLE 4
9
LS9
5
5
D(4)
5
2
J(2)
I(3)
A(5)
6
H(3)
K(1)
3
8
B(2)
1
2
12
13
9
E(3)
G(3)
12
13
C(1)
7
L(2)
4
F(2)
5
7
9
11
Backward pass to determine LS
33
CRITICAL PATH METHOD (CPM) EXAMPLE 4
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
34
5
D(4)
2
J(2)
I(3)
A(5)
6
H(3)
K(1)
3
8
B(2)
1
E(3)
G(3)
C(1)
7
L(2)
4
F(2)
Total Project duration 13 weeks
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