Chapter 6: Product Specifications Product Design and Developments Fifth Edition by Karl T. Ulrich and Steven D. Eppinger

Planning Product Development Process Concept Development Concept Development System-Level Design System-Level Design Detail Design Detail Design Testing and Refinement Testing and Refinement Production Ramp-Up Production 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 Perform Economic Analysis Benchmark Competitive Products Build and Test Models and Prototypes Identify Customer Needs Establish Target Specifications Generate Product Concepts Select Product Concept(s) Set Final Specifications Plan Downstream Development Test Product Concept(s) Development Plan 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

You are now ready to create the PDS for your design 1.Gather customer needs. 2.Benchmark against customer needs. 3.Translate customer needs to metrics. 4.Identify appropriate standards. 5.Add any standards requirements to the metrics. 6.Generate a functional model. 7.Add any functional requirements to the metrics. 8.Benchmark against metrics.

1. Gather customer needs: The spring at 90 degrees sometimes doesn’t shoot – it isn’t clamped down well The device operates properly at all settings. The device remains stationary during use. Klonworks

2. Benchmark against customer needs: For a given customer need, evaluate the selected competitors. NeedRoseKlonworksXpultWoodenGolfHockey The device remains stationary during use.

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 Children’s toys (Safety Requirements) ASTM E (2008) Standard Terminology Relating to Design of Experiments ASTM F 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

Product Function(s) Brainstorming / Directed Search / Inventive Problem Solving Define Customer Requirements Model and Analyze Function Formulate Candidate System Solutions Identify Functional Solutions ++++ OR F1 F2F3F4F5 S1S2S3 6

Functional Modeling Basics Chop Beans Transport People Accept Human ChopperVehicleDoor 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 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. Input 1 Output 1 Input 2 Output 2 Input 3 Output 3 SystemInputsOutputs

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 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 sub- system 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 Hot Water Water Heater Cold Water Electric Current Heats Water Hot Water Cold Water Electric Current Form Function Flow R

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. ToolObject Action

Functional Analysis AutoPassenger Transports System: Automobile ChairPerson Supports System: Chair OvenFood Heats System: Oven

Component Super System Product Useful 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 Needs

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

Loosen Dirt (Fill) Dirty Clothes Separate Dirt (Agitate) Remove Dirt (Rinse) Clean clothes WaterDetergent How Specific ? 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? Higher Order Function Basic Function Required Secondary Function Required Secondary Function Assumed Function

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

Figure 5.5, Otto and Wood

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 ChamberSealSlicing BladeShaftArmature 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

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.

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 ReservoirNarrow barrel NozzleBodyPump

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