Chapter 6: Product Specifications
Product Design and Development
Fifth Edition
by Karl T. Ulrich and Steven D. Eppinger
Reflection on Stakeholder Need Statements from the Quiz.
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Access objects in the bag quickly and
easily.
The person must be able to retrieve items
of interest in an unawkward fashion.
A user should be able to access common
items while standing up with minimal
effort.
Be able to locate items easily in the bag.
Customer needs an easier way to pay for
purchases.
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More storage options for better
organization.
New location for checkbook.
Person needs a way to see into the
backpack easily so that they can find
checkbook easier.
Customer needs bag with compartments
they can reach while wearing the bag.
A wallet with a debit card and built in ID.
Hands free way of holding bag so both
hands can be used in looking for stuff.
Velcro pockets on the outside to hold
wallet, checkbook and such.
Here are suggested solutions the we wrote.
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See how the leather on the bottom of the
bag is all scratched; it’s ugly.
When I’m standing in line at the cashier
trying to find my checkbook while
balancing my bag on my knee, I feel like a
stork.
This bag is my life; if I lose it I’m in big
trouble.
There’s nothing worse than a banana
that’s been squished by the edge of a
textbook.
I never use both straps on my knapsack; I
just sling it over one shoulder.
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The bag maintains its original
appearance with use.
Bag allows easy access to items
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Bag is easy to find.
Bag is difficult to steal.
Bag is hard to lose.
The bag protects fragile items
from damage.
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The bag can rest securely in
multiple modes (either or both
shoulders.)
The bag can be carried
comfortably in multiple modes
(one shoulder strap, two shoulder
straps, or hand hold.)
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Product Development Phases
Planning
Concept
System-LevelDetail
DevelopmentDesign
Design
Testing and Production
Refinement Ramp-Up
We are going into more detail on Concept Development. We did a lecture,
quiz and you have homework assignment on stakeholder needs.
Now we are ready to go to the next step in Concept Development.
Concept Development Process
Identify
Stakeholder
Needs
Establish
Target
Specifications
Generate
Product
Concepts
Select
Product
Concept(s)
Test
Product
Concept(s)
Set
Final
Specifications
Plan
Downstream
Development
Perform Economic Analysis
Benchmark Competitive Products
Build and Test Models and Prototypes
Target Specs
Final Specs
Based on stakeholder
needs and benchmarking
Based on selected concept,
feasibility, models, testing,
and trade-offs
Development
Plan
The Blind Men and the Elephant
A Hindu fable by John Godfrey Saxe
from Elephants Ancient and Modern by
FC Sillar and RM Meyler.
It was six men of Indostan
To learning much inclined,
Who went to see the Elephant
(Though all of them were blind),
That each by observation
Might satisfy his mind.
The First approached the Elephant,
And happening to fall
Against his broad and sturdy side,
At once began to bawl:
`God bless me! but the Elephant
Is very like a wall!'
The Second, feeling of the tusk,
Cried, `Ho! what have we here
So very round and smooth and sharp?
To me 'tis mighty clear
This wonder of an Elephant
Is very like a spear!'
The Third approached the animal,
And happening to take
The squirming trunk within his hands,
Thus boldly up and spake:
`I see,' quoth he, `the Elephant
Is very like a snake.'
The Fourth reached out his eager hand,
And felt about the knee.
`What most this wondrous beast is like
Is mighty plain,' quoth he;
`'Tis clear enough the Elephant
Is very like a tree!'
The Fifth who chanced to touch the ear,
Said: `E'en the blindest man
Can tell what this resembles most:
Deny the fact who can,
This marvel of an Elephant
Is very like a fan!'
The Sixth no sooner had begun
About the beast to grope,
Than, seizing on the swinging tail
That fell within his scope,
`I see,' quoth he, `the Elephant
Is very like a rope!'
And so these men of Indostan
Disputed loud and long,
Each in his own opinion
Exceeding stiff and strong,
Though each was partly in the right,
And all were in the wrong!
So, oft in theologic wars,
The disputants, I ween,
Rail on in utter ignorance
Of what each other mean,
And prate about an Elephant
Not one of them has seen!
Product Design Specifications are difficult to write.
• Basic control and reference document for the design and
manufacture
• Specific, measurable, testable criteria
• “Unambiguous, Understandable, Correct, Concise, Traceable,
Traced, Design Independent, Verifiable, Unique, Complete,
Consistent, Comparable, Modifiable, Attainable”
• Functional decomposition
• Performance targets
• Constraints (Demands, Musts)
• Goals (Wishes, Wants)
• Features
Writing a good PDS is very difficult
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Customer
Regulatory Bodies
Laws of Physics
Functional Analysis
Company Constraints
Social, Political, and Legal Requirements
There are nine suggested steps for generating target
specifications. These have been modified from your text.
1. Gather stakeholder needs.
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3.
4.
5.
6.
7.
Benchmark against stakeholder needs.
Translate stakeholder needs to metrics.
Identify appropriate standards.
Add any standards requirements to the metrics.
Generate a functional model.
Add any functional requirements to the metrics.
8. Benchmark against metrics.
9. Set ideal and acceptable values.
Product Specifications Example:
Mountain Bike Suspension Fork
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
NEED
Imp
reduces vibration to the hands.
3
allows easy traversal of slow, difficult terrain.
2
enables high speed descents on bumpy trails. 5
allows sensitivity adjustment.
3
preserves the steering characteristics of the bike.4
remains rigid during hard cornering.
4
is lightweight.
4
provides stiff mounting points for the brakes.
2
fits a wide variety of bikes, wheels, and tires.
5
is easy to install.
1
works with fenders.
1
instills pride.
5
is affordable for an amateur enthusiast.
5
is not contaminated by water.
5
is not contaminated by grunge.
5
can be easily accessed for maintenance.
3
allows easy replacement of worn parts.
1
can be maintained with readily available tools.
3
lasts a long time.
5
is safe in a crash.
5
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Maniray 2
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ST Tritrack
Start with the Stakeholder Needs. The table below was
generated after interviews had been conducted and analyzed.
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Gunhill Head Shox
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Tonka Pro
Rox Tahx Ti 21
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Rox Tahx Quadra
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
The suspension
NEED
Imp
reduces vibration to the hands.
3
allows easy traversal of slow, difficult terrain.
2
enables high speed descents on bumpy trails. 5
allows sensitivity adjustment.
3
preserves the steering characteristics of the bike.4
remains rigid during hard cornering.
4
is lightweight.
4
provides stiff mounting points for the brakes.
2
fits a wide variety of bikes, wheels, and tires.
5
is easy to install.
1
works with fenders.
1
instills pride.
5
is affordable for an amateur enthusiast.
5
is not contaminated by water.
5
is not contaminated by grunge.
5
can be easily accessed for maintenance.
3
allows easy replacement of worn parts.
1
can be maintained with readily available tools.
3
lasts a long time.
5
is safe in a crash.
5
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ST Tritrack
The next step is to benchmark on stakeholder needs.
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Metrics Exercise: Coffee Cup
Stakeholder Needs:
The coffee cup holds a lot of coffee.
The coffee cup stays cool to the touch.
The coffee cup keeps coffee hot.
The coffee cup looks nice.
The coffee cup feels nice.
The coffee cup is low cost.
The coffee cup does not spill coffee.
Name:_________________________________
Name:_________________________________
Name:_________________________________
CM:_________
CM:_________
CM:_________
Using the available coffee cups, complete the
benchmarking data.
Use 1 * for worst and 5 ***** for best.
holds a lot of coffee
stays cool to the touch
keeps coffee hot
looks nice
feels nice
low cost
does not spill coffee
Need #s
Metric #
Establish Metrics and Units
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1,3
2
2,6
3
1,3
4
1,3
5
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6
5
7
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26
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Metric
Attenuation from dropout to handlebar at 10hz
Spring pre-load
Maximum value from the Monster
Minimum descent time on test track
Damping coefficient adjustment range
Maximum travel (26in wheel)
Rake offset
Lateral stiffness at the tip
Total mass
Lateral stiffness at brake pivots
Headset sizes
Steertube length
Wheel sizes
Maximum tire width
Time to assemble to frame
Fender compatibility
Instills pride
Unit manufacturing cost
Time in spray chamber w/o water entry
Cycles in mud chamber w/o contamination
Time to disassemble/assemble for maintenance
Special tools required for maintenance
UV test duration to degrade rubber parts
Monster cycles to failure
Japan Industrial Standards test
Bending strength (frontal loading)
Imp
Units
3
dB
3
N
5
g
5
s
3 N-s/m
3
mm
3
mm
3 kN/m
4
kg
2 kN/m
5
in
5
mm
5
list
5
in
1
s
1
list
5
subj
5
US$
5
s
5 k-cycles
3
s
3
list
5 hours
5 cycles
5 binary
5
MN
Metrics Exercise: Coffee Cup
Stakeholder Needs:
The coffee cup holds a lot of coffee.
The coffee cup stays cool to the touch.
The coffee cup keeps coffee hot.
The coffee cup looks nice.
The coffee cup feels nice.
The coffee cup is low cost.
The coffee cup does not spill coffee.
Metric #
Need #
Metric
Units
1
1
Capacity
Fluid Ounces
2
2
Mug Outer Temperature
°F
3
3
Coffee Temp after 1 hour
°F
4
4
Consumer Focus Group
Rank
5
5
Consumer Focus Group
Rank
6
6
Price
$
7
7
Dynamic Leak Test
Ounces
Additional Areas to Consider
• Physical requirements
• Functional requirements
• Service environment (comprehensive: insect and bird
damage)
• Kinematics – type of motion, direction, velocity,
acceleration
• Forces - direction, magnitude, frequency, resonance,
stiffness
• Materials – properties of final product, flow of
materials, design for manufacturing
Design Specification Checklist
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Performance At what speed must it operate? How often will it be used (continuous or discontinuous use)?
How long must it last?
Environment (during manufacture, storage and use) All aspects of the product’s likely environment should
be considered: for example temperature, humidity, risk of corrosion, vibration.
Target product cost This is strongly affected by the intended market.
Competition What is the nature and extent of existing or likely competition? Does our specification differ
from the competition? If so, why?
Quantity and manufacture Should it be made in bulk, in batches, or as individual items made to order?
Does it have to be a particular shape? Can we make all the parts or must we buy some in?
Materials Are special materials needed? Do we have experience of working with the likely candidate
materials?
Quality and consistency What levels of quality and consistency does the market expect for this product?
Does every product have to be tested?
Standards Does the product need to conform to any local, international or customer standards? Is the
product safe?
Patents Are there any patents we may either infringe or register?
Packaging and shipping How will the product be packaged? How will the product be distributed?
Aesthetics and ergonomics Is the product easy and fun to use? Is it attractive to the right customer?
Market constraints Does a market already exist or must it be created? What is the likely product lifetime?
How long do we have to get the product to market? What are the customers’ likes and dislikes?
Company constraints Does the product fit in with company image? Are we constrained in material or
process choice? Are there any political considerations?
http://labspace.open.ac.uk/mod/resource/view.php?id=194654
More Things to Think About
• Production – Factory limitations, outsourcing,
tolerancing (You may wait on actual tolerances until
later – just think about the big picture.)
• Assembly
• Transport
• Costs
• Schedule
• Life-cycle issues
• Human factors
Social, Political, Legal
• Safety and environmental regulations
• STANDARDS
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www.ul.com
www.outdoorindustry.com
www.cpsc.gov
http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&tpl=%2Findex.tpl
– www.astm.org
– www.nfpa.org
– http://www.nssn.org/
• Safety and product liability
• Patents and intellectual property
Here is a possible standard for a coffee cup.
BSI
British Standards Institute
Document #: BS ISO 20282-1:2006
Title:
Ease of operation of everyday products. Design requirements for
context of use and user characteristics
Scope:
ISO 20282-1:2006 provides requirements and recommendations
for the design of easy-to-operate everyday products, where ease
of operation addresses a subset of the concept of usability
concerned with the user interface by taking account of the
relevant user characteristics and the context of use.
ISO 20282-1:2006 is intended to be used in the development of
everyday products, for which it defines ease of operation, explains
which aspects of the context of use are relevant, and describes
the characteristics of the intended user population that may
influence usability.
The intended users of this part of ISO 20282-1:2006 are usability
specialists, ergonomists, product designers, interaction designers,
product manufacturers and others involved in the design and
development of everyday products.
ISO 20282-1:2006 is applicable to mechanical and/or electrical products
with an interface that a user can operate directly or remotely to gain
access to the functions provided. These products fall into at least one of
the following categories: consumer products intended for some or all of
the general public which are bought, rented or used, and which may be
owned by individuals, public organizations, or private companies;
consumer products intended to be acquired and used by an individual for
personal rather than professional use (e.g. alarm clocks, electric kettles,
telephones, electric drills); walk-up-and-use products that provide a
service to the general public (such as ticket-vending machines,
photocopying machines, fitness equipment); products used in a work
environment, but not as part of professional activities (e.g. a coffee
machine in an office); products including software that supports the main
goals of use of the product (e.g. a CD player).
This part of ISO 20282 is not applicable to the following: purely physical
products without an interactive user interface (such as a jug or a hammer);
products where appearance or fashion is the main goal (such as a watch
with no markings); products requiring specialist training, specific skills
and/or professional knowledge (such as a musical instrument or a car);
standalone software products; products intended to be used for
professional activities only.
BS EN 12546-1:2000 Materials and articles in contact with foodstuffs.
Insulated containers for domestic use. Specification for vacuum ware,
insulated flasks and jugs
DIN EN 1186-3:2002 Materials and articles in contact with foodstuffs Plastics - Part 3: Test methods for overall migration into aqueous
simulants by total immersion
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Bending strength (frontal loading)
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Japan Industrial Standards test
Special tools required for maintenance
Time to disassemble/assemble for maintenance
Cycles in mud chamber w/o contamination
Time in spray chamber w/o water entry
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Unit manufacturing cost
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Instills pride
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Fender compatibility
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Monster cycles to failure
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UV test duration to degrade rubber parts
•
Time to assemble to frame
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Maximum tire width
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Wheel sizes
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Steertube length
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Headset sizes
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Lateral stiffness at brake pivots
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8
Total mass
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7
Lateral stiffness at the tip
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6
Rake offset
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5
Maximum travel (26in wheel)
Spring pre-load
Need
1
reduces vibration to the hands. •
2
allows easy traversal of slow, difficult terrain.
3
enables high speed descents on bumpy trails. •
4
allows sensitivity adjustment.
5 preserves the steering characteristics of the bike.
6
remains rigid during hard cornering.
7
is lightweight.
8
provides stiff mounting points for the brakes.
9
fits a wide variety of bikes, wheels, and tires.
10
is easy to install.
11
works with fenders.
12
instills pride.
13
is affordable for an amateur enthusiast.
14
is not contaminated by water.
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is not contaminated by grunge.
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can be easily accessed for maintenance.
17
allows easy replacement of worn parts.
18
can be maintained with readily available tools.
19
lasts a long time.
20
is safe in a crash.
4
Damping coefficient adjustment range
3
Minimum descent time on test track
2
Maximum value from the Monster
1
Attenuation from dropout to handlebar at 10hz
Metric
Link Metrics to Needs
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There are nine suggested steps for generating target
specifications. These have been modified from your text.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Gather customer needs. √
Benchmark against customer needs. √
Translate customer needs to metrics. √
Identify appropriate standards. √
Add any standards requirements to the metrics. √
Generate a functional model.
Add any functional requirements to the metrics.
Benchmark against metrics.
Set ideal and acceptable values.