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Chapter 5: Product Specifications. Product Design and Developments Fourth Edition by Karl T. Ulrich and Steven D. Eppinger. Announcements. There will be no lab the week of the career fair. Concept Development Process. Development Plan. Identify Customer Needs. Establish Target - PowerPoint PPT Presentation
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Chapter 5: Product Specifications
Product Design and DevelopmentsFourth Edition
by Karl T. Ulrich and Steven D. Eppinger
Announcements
• There will be no lab the week of the career fair.
Concept Development Process
Perform Economic Analysis
Benchmark Competitive Products
Build and Test Models and Prototypes
IdentifyCustomer
Needs
EstablishTarget
Specifications
GenerateProduct
Concepts
SelectProduct
Concept(s)
Set Final
Specifications
PlanDownstreamDevelopment
TestProduct
Concept(s)
DevelopmentPlan
Target Specs
Based on customer needs and benchmarking
Final Specs
Based on selected concept, feasibility, models, testing, and trade-offs
• 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
Product Design Specifications
Our Approach to PDS
• Process recommended for high-risk new product design.
• PDS development will be modified based on your product or process.
Last Class You Performed Benchmarking on Metrics
Met
ric #
Nee
d #s
Metric Imp Units ST T
ritra
ck
Man
iray
2
Rox
Tah
x Q
uadr
a
Rox
Tah
x Ti
21
Tonk
a Pr
o
Gun
hill
Hea
d Sh
ox
1 1,3 Attenuation from dropout to handlebar at 10hz 3 dB 8 15 10 15 9 132 2,6 Spring pre-load 3 N 550 760 500 710 480 6803 1,3 Maximum value from the Monster 5 g 3.6 3.2 3.7 3.3 3.7 3.44 1,3 Minimum descent time on test track 5 s 13 11.3 12.6 11.2 13.2 115 4 Damping coefficient adjustment range 3 N-s/m 0 0 0 200 0 06 5 Maximum travel (26in wheel) 3 mm 28 48 43 46 33 387 5 Rake offset 3 mm 41.5 39 38 38 43.2 398 6 Lateral stiffness at the tip 3 kN/m 59 110 85 85 65 1309 7 Total mass 4 kg 1.409 1.385 1.409 1.364 1.222 1.1
10 8 Lateral stiffness at brake pivots 2 kN/m 295 550 425 425 325 650
11 9 Headset sizes 5 in1.0001.125
1.0001.1251.250
1.0001.125
1.0001.1251.250
1.0001.125 NA
12 9 Steertube length 5 mm
150180210230255
140165190215
150170190210
150170190210230
150190210220 NA
13 9 Wheel sizes 5 list 26in 26in 26in26in
700C 26in 26in14 9 Maximum tire width 5 in 1.5 1.75 1.5 1.75 1.5 1.515 10 Time to assemble to frame 1 s 35 35 45 45 35 8516 11 Fender compatibility 1 list Zefal none none none none all17 12 Instills pride 5 subj 1 4 3 5 3 518 13 Unit manufacturing cost 5 US$ 65 105 85 115 80 10019 14 Time in spray chamber w/o water entry 5 s 1300 2900 >3600 >3600 2300 >360020 15 Cycles in mud chamber w/o contamination 5 k-cycles 15 19 15 25 18 3521 16,17 Time to disassemble/assemble for maintenance 3 s 160 245 215 245 200 425
22 17,18 Special tools required for maintenance 3 list hex hex hex hexlonghex
hex,pin
wrnch23 19 UV test duration to degrade rubber parts 5 hours 400+ 250 400+ 400+ 400+ 25024 19 Monster cycles to failure 5 cycles 500k+ 500k+ 500k+ 480k 500k+ 330k25 20 Japan Industrial Standards test 5 binary pass pass pass pass pass pass26 20 Bending strength (frontal loading) 5 MN 55 89 75 75 62 102
Metric Units Mar
gina
l Val
ue
Idea
l Val
ue
1 Attenuation from dropout to handlebar at 10hz dB >10 >152 Spring pre-load N 480 - 800 650 - 7003 Maximum value from the Monster g <3.5 <3.24 Minimum descent time on test track s <13.0 <11.05 Damping coefficient adjustment range N-s/m 0 >2006 Maximum travel (26in wheel) mm 33 - 50 457 Rake offset mm 37 - 45 388 Lateral stiffness at the tip kN/m >65 >1309 Total mass kg <1.4 <1.1
10 Lateral stiffness at brake pivots kN/m >325 >650
11 Headset sizes in1.0001.125
1.0001.1251.250
12 Steertube length mm
150170190210
150170190210230
13 Wheel sizes list 26in26in
700c14 Maximum tire width in >1.5 >1.7515 Time to assemble to frame s <60 <3516 Fender compatibility list none all17 Instills pride subj >3 >518 Unit manufacturing cost US$ <85 <6519 Time in spray chamber w/o water entry s >2300 >360020 Cycles in mud chamber w/o contamination k-cycles >15 >3521 Time to disassemble/assemble for maintenance s <300 <16022 Special tools required for maintenance list hex hex23 UV test duration to degrade rubber parts hours >250 >45024 Monster cycles to failure cycles >300k >500k25 Japan Industrial Standards test binary pass pass26 Bending strength (frontal loading) MN >70 >100
We Also Asked You to Assign Marginal and Ideal Values
The Product Specs Process
• Set Target Specifications– Based on customer needs and benchmarks– Develop metrics for each need– Set ideal and acceptable values
• Refine Specifications– Based on selected concept and feasibility testing– Technical modeling– Trade-offs are critical
• Reflect on the Results and the Process– Critical for ongoing improvement
Now What? Can you get there from here?
• Make a functional model of the product• Make a technical model of the product• Make a cost model of the product• Refine the specifications, making trade-offs
where necessary.• Flow down the specifications as appropriate• Reflect on the results and the process.
Functional Analysis/Modeling
• Your text does not do the functional analysis until concept generation.
• There are several methods for Functional Analysis– Product Function (Top-Down)– FAST (Functional Analysis System Technique) (Top-Down)– Subtract and Operate Procedure (Bottom-Up)
• Functional analysis is NOT unique– A way of structuring your thinking about the problem– A way of aiding PDS development– Can also aid in concept generation
Functional Analysis...
• Identifies important system components and their functions.
• Describes how these components functionally interact with each other and super- and sub-systems.
• Clarifies the best problem to solve.
What are we going to do today?
• Define Functions and Sub-functions• Define Systems and Sub-systems• Map Functions through a System• Apply Subtract and Operate Procedure to
Develop a Function Tree
Product Function(s)
Brainstorming / Directed Search / Inventive Problem Solving
Define Customer Requirements
Model and Analyze Function
Formulate Candidate System Solutions
Identify Functional Solutions + + + +
OR OR
F1 F2 F3 F4 F5
S1 S2 S3
6
Functional Modeling Basics
Chop Beans
Transport People
AcceptHuman
Chopper Vehicle Door System
Product Function – What the product does. A statement of relationship between available input and desired output, independent of any particular form. (Overall Function)
Functional Modeling BasicsProduct Sub-function – A component of product
function. The combined effect of two or more product sub-functions is product function.
• Example: Hold Liquid
• Contains liquid
• Insulates liquid
• Insulates hand
• Supports liquid
• Accepts pour
• Interfaces hand
• Pours out
A System...• Is an entity that is connected to its environment by
means of inputs and outputs defined on its boundary,• It can be defined in terms of mechanical construction (form)
or by function, and• It can be decomposed into Sub-systems connected to each
other by means of inputs and outputs defined on their respective boundaries.
Input 1 Output 1
Input 2 Output 2
Input 3 Output 3
SystemInputs Outputs
Functions and Systems• Functions and sub-functions definitions parallel those of
systems and sub-systems but do not necessarily have a one-to-one correspondence.
• A sub-system may serve more than one sub-function.– Exhaust plumbing sub-system contains and transfers engine
exhaust
• Several sub-systems may be needed to provide a single sub-function.– Pump, fan, and radiator sub-systems cool engine
• Several sub-functions can be distributed among several sub-systems.– Sensors, wires, computer, and actuators control, diagnose, and
prognosticate engine function
Functions
Functions should be expressed in terms ofmeasurable effects
Typical function expression: “active verb – noun”
“increase pressure”“transfer torque”
“store energy”“cool liquid”
Is “Low Price” a function?
Functions vs. Goals vs. Constraints• Functions represent what the product does to satisfy the
customer need.• Some customer needs are satisfied by how the product is
implemented in form. These are attributes or features of the product.
• Criteria can be attributes on one product but functions on another. – Example: Storage compactness
Attribute : Make smallFunctional Solution: Make it fold up
• When in doubt: If the criteria is met by an identifiable sub-system doing something, then it is a function; otherwise, it is an attribute.
Goals vs Constraints
• A Constraint is a requirement that MUST be met.– If a constraint is not met, the design is NOT USABLE– Meet FDA requirement for biocompatability
• A Goal is a requirement that may be used to make trade-offs in design decisions.– Minimize cost– Maximize speed
Form Function Flow
Hot Water
Water Heater
Cold Water
Electric Current
Heats WaterHot WaterCold Water
Electric Current
Form
Function
FlowR
Functional Analysis...
• Identifies important system components and their functions.
• Describes how these components functionally interact with each other and super- and sub-systems.
• Clarifies the best problem to solve.
Functional Analysis• Functional relationships can be described using just 3
elements.
• In a function, an object is acted on by a tool.
• The action typically involves a parameter change for the object.
Tool ObjectAction
Functional Analysis
Auto PassengerTransports
System: Automobile
Chair PersonSupports
System: Chair
Oven FoodHeats
System: Oven
Component
Super System
ProductUseful
Harmful
B
D
Monitors Insufficient
Dispenses
Positions Required
Actuates Excessive
Holds E
C
A
Functional Analysis Diagram• Start with your knowledge of the product (or
process) system.• Draw a diagram of the elements and functions.
Verify Functions Against NeedsHolds a lot of coffee L L LStays cool to touch L L L L
Keeps coffee hot (L) L L L LLooks nice
Feels nice (D) D D DLow price
Does not spill (B) B B B B B B B B B
DelighterLinear Satisfier
Basic Requirement
Acc
ept L
iqui
d
Con
tain
Liq
uid
Insu
late
Liq
uid
Con
tact
Air
Inte
rface
Han
d
Insu
late
Han
d
Tran
smit
Load
Insu
late
Sup
port
Sup
port
Con
tain
er
Inte
rface
Mou
th
Con
t. Li
q. /
Intf.
Mou
nth
Con
t. Li
q. /
Insl
. Han
d
Con
t. Li
q. /
Tran
s. L
oad
Product Functions
Cust
omer
Need
s
Example: Washing Machine from Freshman Design
WasherDirty
ClothesClean
Clothes
Loosen
Dirt
(Fill)
Dirty
ClothesSeparate
Dirt
(Agitate)
Remove
Dirt
(Rinse)
Clean
clothes
Water Detergent
HowSpecific ?
This washer should loosen 85% of dirt particles or washer should have inputs for water and detergent assuming that this is the desired mode
Clean Water
Dirty Water
But Wet!!
Remove
Dirt
(Rinse)
Clean
wet
clothes
Clean Water
Dirty Water
Remove
Water
(Spin)
Clean, Damp
Clothes
FAST• Brainstorm all functions that product will
serve in the eyes of the customer.• Select the overall product function• Distinguish between the basic function and
the secondary functions• Arrange functions in a critical path
How? Why?
HigherOrder
Function
BasicFunction
RequiredSecondaryFunction
RequiredSecondaryFunction
AssumedFunction
GrinderOperator
Coffee Beans
EnergySystem
Ground Coffee
Chamber
SealSlicing blade
Figure 5.5, Otto and Wood
Subtract and Operate Procedure1. Disassemble (subtract) one component of the
assembly.2. Operate the system through its full range.3. Analyze the effect.4. Deduce the subfunction of the missing component.5. Replace the component and repeat n times where n
is the number of components in the assembly.6. Translate the collection of subfunctions into a
function tree.
Elements for Subtraction with ResultsChamber Seal Slicing Blade Shaft Armature
No defined way of holding content
No protection against contents splattering
Contents won’t be chopped
Slicing blade won’t be attached
Shaft doesn’t spin
No measurable volume
No protection against spinning blade
No resistance to torque
Contents will not be chopped
Electricity is not transformed into mechanical energy
No body to measure contents
Chamber can’t be closed
No resistance to torque
No body to contain contents
Impact noise will not be enclosed
No body to hold apparatus
Might not be able to turn on if safety feature
Looks bad
Difficult to clean undefined bodyPour out contents
Scan in Figure 5.6 Otto and Wood
Quiz for TodayCreate a functional diagram for a squirt gun using the subtract and operate procedure.
http://entertainment.howstuffworks.com/water-blaster1.htm
The Classic Water GunBefore the 1980s, water guns had fairly limited capabilities. Handheld pistols could only shoot water a short distance. They shot a weak, narrow stream and you had to run to a spigot to refill them after every shoot-out. These guns are still terrific toys, of course, and they're a wonderful demonstration of basic plumbing principles. In a classic squirt gun, there are just a few basic parts: 1.There is a trigger lever, which activates a small pump. 2.This pump is attached to a plastic tube that draws water from the bottom of the reservoir (in most cases, the reservoir is the entire inside of the gun). 3.The pump forces this water down a narrow barrel and out a small hole at the gun's muzzle. 4.The hole, or nozzle, focuses the flowing water into a concentrated stream. For the purposes of your quiz, assume that there is a trigger lever, plastic tube, reservoir, narrow barrel, nozzle, body and pump. Furthermore, you may assume that the pump has both one-way valves attached to it and that the pump and valves act as a unit.
The only complex element in this design is the water pump, and it's about as simple as they come. The main moving element is a piston, housed inside a cylinder. Inside the cylinder is a small spring. To operate the pump: You pull the trigger back, pushing the piston into the cylinder. This compresses the spring, causing it to push the piston back out of the cylinder when you release the trigger. These two strokes of the piston, into the cylinder and out again, constitute the entire pump cycle. The downstroke, the piston pushing in, shrinks the volume of the cylinder, forcing water or air out of the pump. The upstroke, the spring pushing the piston back out, expands the cylinder volume, sucking water or air into the pump. In a water gun, you need to suck water in from the reservoir below and force it out through the barrel above. In order to get all the water moving through the barrel, the pump must only force water up -- it cannot force water back into the reservoir. In other words, the water must move through the pump in only one direction. The device that makes this possible is called a one-way valve. The one-way valve in a basic squirt pistol consists of a tiny rubber ball that rests neatly inside a small seal. There are two one-way valves: one between the reservoir and the pump, and another between the pump and the nozzle.
Name:_________________________CM:______Name:_________________________Name:_________________________
Trigger Lever
Plastic Tube
Reservoir Narrow barrel
Nozzle Body Pump
List Functions identified, but don’t attempt to structure your solution.
Now What? Can you get there from here?
• Make a functional model of the product• Make a technical model of the product• Make a cost model of the product• Refine the specifications, making trade-offs
where necessary.• Flow down the specifications as appropriate• Reflect on the results and the process.