Chapter 5: Product Specifications

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 Development 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

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.

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.

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

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. 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

14. 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

15. 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

16. A System... • Is an entity that is connected to its environment bymeans 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-systemsconnected 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

17. 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

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

19. Is “Low Price” a function?

20. 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 compactnessAttribute : 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.

21. 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

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

23. 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.

24. Action Tool Object 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.

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

26. B Monitors Insufficient E Holds Actuates Excessive Dispenses Positions Required Super System Useful Product D A C Harmful Component Functional Analysis Diagram • Start with your knowledge of the product (or process) system. • Draw a diagram of the elements and functions.

27. Verify Functions Against Needs

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

29. 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

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

31. 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

32. How? Why? Higher Order Function Basic Function Required Secondary Function Required Secondary Function Assumed Function

33. Chamber Slicing blade Seal Energy System Operator Grinder Ground Coffee Coffee Beans

34. Figure 5.5, Otto and Wood

35. 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.

36. Elements for Subtraction with Results

37. Scan in Figure 5.6 Otto and Wood

38. Quiz for Today Create a functional diagram for a squirt gun using the subtract and operate procedure. http://entertainment.howstuffworks.com/water-blaster1.htm

39. 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.

40. 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.

41. Name:_________________________CM:______Name:_________________________Name:_________________________Name:_________________________CM:______Name:_________________________Name:_________________________

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

43. 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.