1. Chapter 5: Product Specifications
Product Design and Developments
Fourth Edition
by Karl T. Ulrich and Steven D. Eppinger

2. Announcements
There will be no lab the week of the career fair.

3. Concept Development Process
Plan
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
Based on customer needs and benchmarking
Final Specs
Based on selected concept, feasibility, models, testing, and trade-offs
For Senior Design, you may only get to the point of identifying target specs.

4. 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

5. Our Approach to PDS
Process recommended for high-risk new product design.
PDS development will be modified based on your product or process.
Emphasize that the process that we are teaching is typically used for new product and/or high risk product development
If this is a product that you have made before, you will likely take the old PDS and update it as necessary. It might not even be necessary.

6. Last Class You Performed Benchmarking on Metrics

7. We Also Asked You to Assign Marginal and Ideal Values

8. 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

9. 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.
I’m adding a step here. Let’s insist that they do some functional modeling.

10. 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 aids in organizing the design team, it also allows you to have an abstraction level between need and form. In the past, we looked at what the customer needed and then selected forms (objects, subsystem) based on our experience. The Functional Analysis proposed emphasizes going from the customer needs - functions necessary to fulfill those needs. Then forms for generating the functions are considered.

11. 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.

12. 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

13. Abstraction Level Changes
After benchmarking concurrent with concept development
Much different than specifications for subassemblies
Usually two levels of specs
High Level Requirements
Interaction with external environment
Interaction between top-level functions
Detail level
Major Communication to Your Client in ME471/472
High level – interface with user, human action causes screw to turn. Handle, plastic handle with black rubber coating

14. 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 OR S1 S2 S3

15. 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
Transport People
Accept
Human
Chopper
Vehicle
Door System

16. 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

17. 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

18. 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

19. Typical function expression: “active verb – noun”
Functions
Functions should be expressed in terms of
measurable effects
Typical function expression: “active verb – noun”
“increase pressure”
“transfer torque”
“store energy”
“cool liquid”

20. Is “Low Price” a function?
No – it is probably a goal; systems engineering calls it a feature

21. 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: 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.

22. 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

23. Form  Function  Flow Electric Current R Electric Current Form
Water Heater
Hot Water
Cold Water
Function
Electric Current R
Flow
Cold Water
Hot Water
Heats Water
Electric Current

24. 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.

25. 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
Object
Action

26. Functional Analysis Auto Passenger Transports System: Automobile Chair
Person
Supports
System: Chair
Oven
Food
Heats
System: Oven

27. Functional Analysis Diagram
Start with your knowledge of the product (or process) system.
Draw a diagram of the elements and functions. B D
Monitors Insufficient
Dispenses
Positions Required
Actuates Excessive
Holds E C A
The blue boxes represent “parts” of the system. One source of these “parts” could be the process map - Input Variables, Output Variables or Process Step.
Component
Super System
Product
Useful
Harmful

28. Verify Functions Against Needs

29. Example: Washing Machine from Freshman Design
Dirty Clothes
Clean Clothes
Washer

30. How
Specific ?
Dirty Water
Clean
clothes
Dirty
Clothes
Loosen
Dirt
(Fill)
Separate
Dirt
(Agitate)
Remove
Dirt
(Rinse)
But Wet!!
Water
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

31. Dirty Water
Remove
Dirt
(Rinse)
Clean
wet
clothes
Remove
Water
(Spin)
Clean Water
Clean, Damp Clothes

32. 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
Functional Analysis System Technique

33. How? Why? Higher Order Function Basic Function Required Secondary
Assumed
Function
I don’t get this arrangement at all. I show it because there may be some global thinkers who like it.

34. Chamber Slicing blade Seal Energy System Operator Grinder
Ground Coffee
Explain that you put in coffee beans, put on the lid, plug it in, turn it on, and the grinder turns it into coffee dust? What do you call this?
I have drawn a rough domain diagram, but it doesn’t specify the functions, it just indicates where interactions might occurr
Coffee Beans

35. Figure 5.5, Otto and Wood
Example of Coffee Grinder from this approach, it doesn’t really make sense to me. I just don’t think this way – it is ok that I don’t think like this!

36. Subtract and Operate Procedure
Disassemble (subtract) one component of the assembly.
Operate the system through its full range.
Analyze the effect.
Deduce the subfunction of the missing component.
Replace the component and repeat n times where n is the number of components in the assembly.
Translate the collection of subfunctions into a function tree.
Assumes that the product already exist.
The subtraction need not be done literally. It can be imagined.
I actually do a combination of the two approaches. I try to start with the overall process and then I am forced to go to the bottom up because that is the way that I think.

37. Elements for Subtraction with Results
Chamber
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 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

38. Scan in Figure 5.6 Otto and Wood
Insert solution from book

39. Quiz for Today
Create a functional diagram for a squirt gun using the subtract and operate procedure.

40. 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:
There is a trigger lever, which activates a small pump.
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).
The pump forces this water down a narrow barrel and out a small hole at the gun's muzzle.
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.

41. 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.

42. Name:_________________________CM:______ Name:_________________________ Name:_________________________
Trigger Lever
Plastic Tube
Reservoir
Narrow barrel
Nozzle
Body
Pump

43. List Functions identified, but don’t attempt to structure your solution.

44. 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.
Ok, it has been a day since we showed this slide. I just repeated it
Imagine you’re doing computer memory, each additional gigabyte costs something (making thumb drives) Fixed cost + memory+ We will do this at the end of the quarter.