FORMULATING A DESIGN PROBLEM PART 2. Pengumuman – dari Puan Marina Sila download lab module untuk...
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Transcript of FORMULATING A DESIGN PROBLEM PART 2. Pengumuman – dari Puan Marina Sila download lab module untuk...
Pengumuman – dari Puan Marina
• Sila download lab module untuk minggu depan dari portal lab project management
• Hantar drawing in template (assignment minggu lepas) next week by lab session. (except student baru). Individual. 1 day late submission -50%.
• In the detail drawing:• 1. title block• 2. top, front, left, iso view(3rd angle projection)• 3. dimensions
Recap
• Objectives the desired attributes of a design.
• Constraints strict limits that a design must meet to be acceptable.
Objective Tree
• A graphical representation of the objectives for the product.
• The top-level objectives in an objective tree, which is presented as a node at the peak of the tree, is decomposed or broken down into sub-objectives that are at differing levels of importance or that include progressively more details, so that the tree reflects an hierarchical structure as it expands downward.
• Ordered lists of the desired attributes of a design.• Sub-objective tells how to realize the top objective
Safe ladder objectives 1. The ladder should be safe
1.1 The ladder should be stable1.1.1 Stable on floors and smooth surfaces1.1.2 Stable on relatively level ground
1.2 The ladder should be reasonably stiff 2. The ladder should be marketable
2.1 The ladder should be useful 2.1.1 The ladder should be useful indoors
2.1.1.1 Useful to do electrical work2.1.1.2 Useful to do maintenance work
2.1.2 The ladder should be useful outdoors2.1.3 The ladder should be of the right weight
2.2 The ladder should be relatively inexpensive2.3 The ladder should be portable
2.3.1 The ladder should be light in weight2.3.2 The ladder should be small when ready for transport
2.4 The ladder should be durable
electrical
maintenance
small, transportable
light in weight
of right weight
outdoors
indoors
on level ground
on floors
inexpensive
portable
durable
useful
stiff
stable
Safe
SAFE LADDER
Marketable
Objective Tree for Safe Ladder
electrical
maintenance
small, transportable
light in weight
of right weight
outdoors
indoors
on level ground
on floors
inexpensive
portable
durable
useful
stiff
stable
Safe
SAFE LADDER
Marketable
electrical
maintenance
small, transportable
light in weight
of right weight
outdoors
indoors
on level ground
on floors
inexpensive
portable
durable
useful
stiff
stable
Safe
SAFE LADDER
Marketable
Pairwise Comparison Chart
• Helps to understand the relative importance of the objectives comparing objectives.
• To identify the values of objectives or their importance relative to one another and to order them accordingly.
• Procedure:1. compare every objectives with each of the remaining objectives individually2. add cumulative or total scores for each one of the objectives.
Objectives Cost Portability Usefulness Durability Score
Cost - 0 0 1 1
Portability 1 - 1 1 3
Usefulness 1 0 - 1 2
Durability 0 0 0 - 0
• 4 objectives are compared.• The entries in each box of the chart are determined as
binary choices, i.e. every entry is either a 1 or a 0. • The PCC for the ladder design shows that the objectives
ranked in the order of decreasing value or importance is:portability usefulness cost durability
A pairwise comparison chart (PCC) for a ladder design
Quality Function Deployment
• What is quality? 1. (Time magazine (1989))i. Works as it should ii. Lasts a long timeiii. Easy to maintain
2. Garvin (1987)i. Performanceii. Features iii. Reliability iv. Durability v. Serviceability vi. Conformance to conventions/
standardsvii. Aesthetics viii.Perceived quality/ reputation
of manufacturer
• A quality product:i. made of quality parts, which
are made by high-quality processes
ii. Functions or performs as expected (reliable)
iii. Lasts a long time (durable)iv. Easy to maintain
(serviceable)
Quality Function Deployment (QFD)
• A technique for identifying customer requirements and matching them with engineering design and performance parameters.
• Comes from a Japanese phrase “ … the strategic arrangement (deployment) throughout all aspects of a product (functions) of appropriate characteristics (qualities) according to customer demands.”
• Useful tool for formulating design problems for products in situations where several competing products are already on the market.
• QFD Table a chart that explicitly depicts the key relationships between customer requirements, engineering (or product) requirements, and the characteristics of competing products.
• General arrangement (5 regions):1. Customer requirements2. Engineering requirements3. Matrix of requirements relations4. Competitive benchmarks5. Engineering targets
Refer to notes on customer requirement
Quantifiable aspects of the system that can contribute to satisfying Customer Requirements.
Benchmarking -Comparing your design with that of competitors
Indicates the relationship between an engineering requirement and a customer requirement by an ‘x’ mark in the appropriate cell in the matrix.
Lists the units and the numerical values of the targets for each engineering requirement.
House of Quality-one variation of QFD
slid
es (
yes/
no)
fric
tion
fact
or
star
t sw
itch
forc
e (lb
f)
forc
e to
sha
rpen
(lb
f)
hold
forc
e re
quire
d (lb
f)
gras
p to
rque
(in
-lbf)
shav
ings
sto
reag
e (c
u.in
.)
no. s
teps
to e
mpt
y
120
VA
C (
yes/
no)
cord
leng
th (
ft)
poin
t con
e an
gle
(deg
rees
)
no. h
ands
to o
pera
te
wei
ght (
oz)
poin
t rou
ghne
ss (
mic
ro in
.)
Customer Requirements 1 2 3 4 5 6 7 8 9 10 11 12 13 14 CP A B
1 doesn't slide w hen using 0.10 9 3 3 3 9 1 3 3 0.92 needs little insertion force 0.05 9 9 0.83 requires little insertion torque 0.05 9 0.94 operates w hen pencil is inserted0.15 9 9 1.05 collects pencils shavings w ell 0.05 9 1 1.06 empties shavings easily 0.20 3 9 1 3 -3 0.67 plugs into w all socket easily 0.05 9 0.98 cord is long enough 0.05 9 0.89 grinds pencil to sharp point 0.20 9 3 0.7
10 needs only one hand tw o operate0.10 3 9 3 0.8
Total Importance 1.00
Performance current product(CP)
competitior A: Model #25 N 1 0 0 0 0 2 6 Y 6 20 1 20 6
competitor B
New Product Targets N 1 0 0 0 0 3 4 Y 6 18 1 18 5
Customer Satisfactio
n Rating (0.00 - 1.00)
Engineering Characteristics (units)
Im
po
rtan
ce w
t.
1 -311
-3
39
9
-9
9
31
-9
3
-3
11
House of Quality (for Product Planning)
• Room 1: Customer Requirements• Room 2: Customer Importance Weights• Room 3: Engineering Characteristics • Room 4: Correlation Ratings Matrix • Room 5: Benchmark Satisfaction Ratings• Room 6: Benchmark Performance• Room 7: New Product Targets• Room 8: Coupling Matrix