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Reverse Engineering. Establishing Product Functions. Learning Objectives. Understand the concept of functional analysis and its role in the design process Use a “Subtract and Operate” procedure to develop a function tree for ….. - PowerPoint PPT Presentation
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Reverse Engineering
Establishing Product Functions
Learning Objectives
• Understand the concept of functional analysis and its role in the design process
• Use a “Subtract and Operate” procedure to develop a function tree for …..
• Use the function tree to develop a Function Structure diagram for ……
Reading
• Required Reading– Chapter 9– Establishing Product Functions handout
• Suggested reading– Appendix A - Function Structure Definitions
handout– Subtract & Operate handout
Functional Modeling and AnalysisProblem definition
ClarificationCustomer requirements
Distinguish constraints
Generate functions tree
Compare with customers requirements Create alternative
function structures
Identify product architecture and
assemblies
Functional analysis is an integral part of product design and re-design:A way of structuring your thinking about the problemA way of aiding Product Design Specifications developmentCan also aid in concept generation
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
Generating Concepts
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
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/Modeling
• There are several methods for Functional Analysis– Product Function (Top-Down) --- Dissection– FAST (Functional Analysis System Technique) (Top-
Down)– Subtract and Operate Procedure (Bottom-Up) ---
Dissection
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
Functions should be expressed in terms ofmeasurable effects
Typical function expression: “active verb – noun”
“increase pressure”“transfer torque”
“store energy”“cool liquid”
Some functions that products/parts perform
amplify dissipate protect change fasten release channel heat rotate collect hold separate conduct increase store control join supply convert lift support cool lower transform decrease move translate
Refer to Appendix A - Function Structure Definitions handout for detailed description of functions.
Function & Flows
Function
Energy
Material
Signal
Energy
Material
Signal
State 1 State 2
All product activities involve changing the state of three basic quantities: energy, material and signal. We call this change of state a “flow”.
Form Function Flow
Hot Water
Water Heater
Cold Water
Electric Current
Heats WaterHot WaterCold Water
Electric Current
Form
Function
Flow
R
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 : Small sizeFunctional 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.
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.
GrinderOperator
Coffee Beans
EnergySystem
Ground Coffee
Chamber
SealSlicing blade
Example: Coffee Grinder
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 body
Pour out contents
The Subtract and Operate procedure helps us determine the critical functions and subfunctions of our device. These can be mapped to a function tree similar to figure 5.6 from Otto and Wood.
Function Tree
Steps in Creating a Function Structure
• Identify the overall function. In our case, this is the top block in the function tree.
• Identify the basic individual functions that are required to accomplish this task. We have already done this in the first row of functions of the Function Tree.
• Identify more precise functions from the basic functions determined in the previous step. Note that these two steps will be iterative. These more precise functions are the second level of blocks in the Function Tree.
• Arrange the function blocks in the order that they must occur to accomplish the desired overall function. This is a flow chart of functions in which order is important. The easiest way for us to do this is to take the 3x5 cards we used to make the function tree and place them in position until the group is satisfied.
• Add the energy, material, and signal flows between the function blocks as appropriate.
• Double check to make sure you haven’t missed a function block or flow line. • Reproduce the function diagram electronically.
Function Structure
Thick arrows: material flow Thin arrows: energy flow
Where to go from here?
• SOP for flash light• Generate SOP table• Generate function tree• Generate function structure• All of this is due next Monday
Activity for Today
Apply SOP on flashlight / spot light you have
1. Case - A very thin spring or strip of metal (usually copper or brass) that is located throughout the flashlight, making the electrical connection between the various parts – the batteries, the lamp and the switch. These parts conduct electricity and “hook everything up”, completing the circuit.2. Contacts - Deeper grooves for easier hold.3. Switch - The flow of electricity is activated when you push the switch into the ON position, giving you light. The flow of electricity is broken when the switch is pushed into the OFF position, thus turning off the light.4. Reflector - A plastic part, coated with a shiny aluminum layer that rests around the lamp (bulb, LED) and redirects the light rays from the lamp to allow a steady light beam, which is the light you see emitting from the flashlight.5. Lamp - The light source in a flashlight. In most flashlights, the lamp is either a tungsten filament (incandescent bulb) or a light emitting diode (solid state bulb), also known as an LED. The lamp glows when electricity flows through it, thus producing visible light. Incandescent bulb must be replaced when the tungsten filament breaks. An LED contains a very small semiconductor (diode) that is encapsulated in epoxy. LEDs in flashlights are widely considered “unbreakable” – a lifetime lamp.6. Lens- Clear, plastic part you see on the front of the flashlight that protects the lamp.7. Batteries- When activated, batteries are the power source for your flashlight.
http://www.energizer.eu/eu/ee/site/how-flashlights-work.html
Case Contacts Switch Batteries Reflector Lamp / LED
Lens