Transcript Chapter 6: Product Specifications Product Design and Developments Fifth Edition by Karl T.

Chapter 6: Product Specifications
Product Design and Developments
Fifth Edition
by Karl T. Ulrich and Steven D. Eppinger
Product Development Process
Planning
Concept
System-LevelDetail
DevelopmentDesign
Design
Testing and Production
Refinement Ramp-Up
Remember that we are looking at an overall Product Development Process.
We are going into more detail on Concept Development.
Concept Development Process
Identify
Customer
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 customer needs
and benchmarking
Based on selected concept,
feasibility, models, testing,
and trade-offs
Development
Plan
Product Design Specifications
• 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
You are now ready to create the PDS for your design
1.
2.
3.
4.
5.
6.
7.
8.
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.
1. Gather customer needs: The spring at 90 degrees
sometimes doesn’t shoot – it isn’t clamped down well
Klonworks
The device operates properly at all settings.
The device remains stationary during use.
2. Benchmark against customer needs: For a given
customer need, evaluate the selected competitors.
Need
The device remains
stationary during use.
Rose
Klonworks Xpult
Wooden Golf
Hockey
3. Translate Customer Needs to Metrics
The device remains stationary during use.
After activation, the device moves less that
1” in any direction.
4. Identify appropriate standards for your design.
AS 1647.2-1992 Children’s toys (Safety Requirements)
ASTM E1325-02(2008) Standard Terminology Relating to
Design of Experiments
ASTM F589 -06 Standard Consumer Safety Specification for
NON-POWDER GUNS
Translate standard requirements to metrics.
All exposed surfaces must be smooth so that skin is
not broken by contact with the surface.
6. Generate a functional model.
• 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
Define
Customer
Requirements
Product
Function(s)
Model and
Analyze
Function
Brainstorming / Directed Search / Inventive Problem Solving
Identify
Functional
Solutions
+
+
F1
F2
+
+
F3
F4
F5
6
Formulate Candidate
System Solutions
OR
S1
OR
S2
S3
Functional Modeling Basics
Product Function – What the product does. A statement of relationship
between available input and desired output, independent of any particular
form. (Overall Function)
Chop
Beans
Chopper
Transport
People
Vehicle
Accept
Human
Door System
Functional Modeling Basics
Product 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.
Inputs
System
Outputs
Input 1
Output 1
Input 2
Output 2
Input 3
Output 3
Functions and Systems
• Functions and sub-functions definitions parallel those of
systems and sub-systems but do not necessarily have a oneto-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 subfunction.
– Pump, fan, and radiator sub-systems  cool engine
• Several sub-functions can be distributed among several subsystems.
– Sensors, wires, computer, and actuators  control, diagnose, and
prognosticate engine function
Functions
Functions should be expressed in terms of
measurable 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 small
Functional Solution: Fold element
• When in doubt: If the criteria is met by an identifiable subsystem doing something, then it is a function; otherwise, it
is an attribute or feature.
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
Form
Water Heater
Hot Water
Cold Water
Electric Current
Function
R
Flow
Cold Water
Heats Water
Electric Current
Hot Water
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.
Action
Tool
Object
• In a function, an object is acted on by a tool.
• The action typically involves a parameter change for the
object.
Functional Analysis
System: Automobile
Transports
Auto
Passenger
System: Chair
Supports
Chair
Person
System: Oven
Heats
Oven
Food
Functional Analysis Diagram
• Start with your knowledge of the product (or
process) system.
• Draw a diagram of the elements and functions.
A
Holds
B
Monitors
Insufficient
E
Actuates
Excessive
Dispenses
C
Positions
Required
Super System
D
Useful
Product
Harmful
Component
Customer
B
Contain Liquid
Delighter
Linear Satisfier
Basic Requirement
B
Accept Liquid
Holds a lot of coffee
Stays cool to touch
Keeps coffee hot (L)
Looks nice
Feels nice (D)
Low price
Does not spill (B)
B
Product Functions
D
B
B
B
B
B
Cont. Liq. / Insl. Hand
Cont. Liq. / Trans. Load
B
D
Cont. Liq. / Intf. Mounth
D
Interface Mouth
L
L
Support Container
L
L
L
Insulate Support
L
Transmit Load
L
Insulate Hand
Interface Hand
L
Contact Air
Insulate Liquid
Needs
Verify Functions Against Needs
L
L
L
Example: Washing Machine
from Freshman Design
Dirty
Clothes
Washer
Clean
Clothes
How
Specific ?
Dirty
Dirty Water
Clean
Loosen
Separate
Remove
Dirt
Dirt
Dirt
(Fill)
(Agitate)
(Rinse)
Clothes
Water
clothes
But
Wet!!
Detergent
Clean Water
This washer should loosen 85% of dirt
particles or washer should have inputs
for water and detergent assuming that
this is the desired mode
Dirty Water
Remove
Dirt
(Rinse)
Clean
Remove
wet
Water
clothes (Spin)
Clean Water
Clean,
Damp
Clothes
Chamber
Slicing
blade
Seal
Energy
System
Operator
Grinder
Coffee
Beans
Ground Coffee
Subtract and Operate Procedure
1. 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 Results
Chamber
Seal
Slicing Blade
Shaft
No defined way
of holding
content
No protection
against contents
splattering
Contents won’t
be chopped
Slicing blade
Shaft doesn’t
won’t be attached spin
No measurable
volume
No protection
against spinning
blade
No resistance to
torque
Contents will not
be chopped
No body to
measure contents
Chamber can’t be
closed
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 body
Pour out contents
No resistance to
torque
Armature
Electricity is not
transformed into
mechanical
energy
Scan in Figure 5.6 Otto and Wood
Quiz for Today
Create a functional diagram for a squirt gun using the subtract and
operate procedure.
http://entertainment.howstuffworks.com/water-blaster1.htm
The Classic Water Gun
Before 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.