Product Design

Lecture Outline

The design process Concurrent engineering Design for Manufacture Failure Modes and Effects Analysis Value analysis Quality Function Deployment (QFD)

Product Design

Specifies materials Determines dimensions & tolerances Defines appearance Sets performance standards

An Effective Design Process

Matches product characteristics with customer needs

Meets customer requirements in simplest, most cost-effective manner

Reduces time to market Minimizes revisions

Breaking Down Barriers

Stages In The Design Process Idea Generation

Product Concept

Feasibility Study Performance Specifications

Preliminary Design Prototype

Final Design Final Design Specifications

Process PlanningManufacturing Specifications

No

Ideageneration

Finaldesign

Preliminarydesign

Feasibilitystudy

Processplanning

Productfeasible?

Yes

Prototype

Manufacturing

Design & ManufacturingSpecifications

The Design Process

Idea Generation

Suppliers, distributors, salespersons Trade journals and other published material Warranty claims, customer complaints, failures Customer surveys, focus groups, interviews Field testing, trial users Research and development

More Idea Generators

Perceptual Mapsvisual comparison of customer perceptions

Benchmarkingcomparing product/service against best-in-class

Reverse engineeringdismantling competitor’s product to improve your own product

Perceptual Map Of Breakfast CerealsGood taste

Bad taste

High nutritionLow nutrition

•Cocoa Puffs

•Rice Krispies •Wheaties

•Cheerios

•Shredded Wheat

Feasibility Study

Market Analysis

Economic Analysis

Technical / Strategic Analysis

Preliminary Design

Create form & functional design Build prototype Test prototype Revise prototype Retest

Form Design(How The Product Looks)

Functional Design(How The Product Performs)

Reliabilityprobability product performs intended function for specified length of time

Maintainabilityease and/or cost or maintaining/repairing product

Computing Reliability

0.90 0.90

.95

.90

0.90 x 0.90 = 0.81

0.95 + 0.90(1-0.95) = 0.995

Components in series

Components in parallel

Final Design & Process Planning

Produce detailed drawings & specifications Create workable instructions for

manufacture Select tooling & equipment Prepare job descriptions Determine operation & assembly order Program automated machines

Distribution Of Design Changes

21 12 33 ProductionbeginsMonths

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mb

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of D

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Ch

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es Company 1

90% of Totalchangescomplete

Company 2

Improving The Design Process

1. Design teams

2. Concurrent design

3. Design for manufacture & assembly

4. Design for environment

5. Measure design quality

6. Utilize quality function deployment

7. Design for robustness

Design Teams

Marketing, manufacturing, engineering

Suppliers, dealers, customers

Lawyers, accountants, insurance companies

Concurrent Design

Customers

Marketing

Design

Engineering

Suppliers Production

Concurrent Design Also, simultaneous or concurrent engineering Simultaneous decisionmaking by design teams Integrates product design & process planning Details of design more decentralized Encourages price-minus not cost-plus pricing Needs careful scheduling - tasks done in parallel

General Performance Specifications

Instructions to supplier: “Design a set of brakes that can stop a 2200 pound car from 60 miles per hour in 200 feet ten times in succession without fading. The brakes should fit into a space 6” x 8” x 10” at the end of each axle and be delivered to the assembly plant for $40 a set.”

Supplier submits design specifications and prepares a prototype for testing.

Role Of Design Engineer

No longer totally responsible for product design

Responsible for more than what was traditionally considered “design”

Merging of design engineer and manufacturing engineer

Design For Manufacture

Design a product for easy & economical production

Consider manufacturability early in the design phase

Identify easy-to-manufacture product-design characteristics

Use easy to fabricate & assemble components Integrate product design with process planning

DFM Guidelines

Minimize the number of parts Develop a modular design Design parts for multi-use Avoid separate fasteners Eliminate adjustments Design for top-down assembly Design for minimum handling

DFM Guidelines

Avoid tools Minimize subassemblies Use standard parts when possible Simplify operations Design for efficient and adequate testing Use repeatable & understood processes Analyze failures Rigorously assess value

Design Simplification(c) Final design

Design for push-and-snap assembly

(b) Revised design

One-piece base & elimination of fasteners

(a) The original design

Assembly using common fasteners

More Design Improvements

Standardizationuses commonly available parts

reduces costs & inventory Modular design

combines standardized building blocks/modules into unique products

Design For Assembly (DFA)

Procedure for reducing number of parts Evaluate methods for assembly Determine assembly sequence

Analyzing Failures

Failure Mode and Effects Analysis (FMEA)a systematic approach for analyzing causes &

effects of failures

prioritizes failures

attempts to eliminate causes Fault Tree Analysis (FTA)

study interrelationship between failures

Failure Mode & Effects AnalysisFailure Mode

Causes of Failure

Effects of Failure

Corrective Action

Stale Low moisture content, expired shelf life, poor packaging

Tastes bad, won’t crunch, thrown out, lost sales

Add moisture, cure longer, better package seal, shorter shelf life

Broken Too thin, too brittle, rough handling, rough use, poor packaging

Can’t dip, poor display, injures mouth, choking, perceived as old, lost sales

Change recipe, change process, change packaging

Too Salty Outdated recipe, process not in control, uneven distribution of salt

Eat less, drink more, health hazard, lost sales

Experiment with recipe, experiment with process, introduce low salt version

Fault Tree For Potato Chips

And

Or

Value Analysis (Engineering)

Ratio of value / cost Assessment of value :

1. Can we do without it?

2. Does it do more than is required?

3. Does it cost more than it is worth?

4. Can something else do a better job?

5. Can it be made by less costly method, tools, material?

6. Can it be made cheaper, better or faster by someone else?

Design For Environment

Design from recycled material Use materials which can be recycled Design for ease of repair Minimize packaging Minimize material & energy used during

manufacture, consumption & disposal

Measures Of Design Quality

Number of component parts and product options

Percentage of standard partsUse of existing manufacturing resourcesCost of first production runFirst six months cost of engineering

changes

Measures Of Design Quality

First year cost of field service repairTotal product costTotal product salesSustainable development

Quality Function Deployment (QFD)

Translates the “voice of the customer” into technical design requirements

Displays requirements in matrix diagrams First matrix called “house of quality” Series of connected houses

House Of Quality

6. Technical assessment and target values

1. Customerrequirements

4. Relationship matrix

3. Productcharacteristics

Importance

2. Competitiveassessment

5. Tradeoffmatrix

Series Of QFD Houses

Benefits Of QFD

Promotes better understanding of customer demands

Promotes better understanding of design interactions

Involves manufacturing in the design process Breaks down barriers between functions and

departments Focuses the design effort

Benefits Of QFD Fosters teamwork Improves documentation of the design and

development process Provides a database for future designs Increases customer satisfaction Reduces the number of engineering changes Brings new designs to the market faster Reduces the cost of design and manufacture

Design For Robustness

Product can fail due to poor design quality Products subjected to many conditions Robust design studies

controllable factors - under designer’s control

uncontrollable factors - from user or environment Designs products for consistent performance

Consistency Is Important

Consistent errors are easier to correct than random errors

Parts within tolerances may yield assemblies which aren’t

Consumers prefer product characteristics near their ideal values

Technology In Design

CAD - Computer Aided Designassists in creating and modifying designs

CAE - Computer Aided Engineeringtests & analyzes designs on computer screen

CAD/CAM - Design & Manufacturingautomatically converts CAD data into processing instructions for computer controlled equipment

Benefits Of CAD

Produces better designs faster Builds database of designs and creates

documentation to support them Shortens time to market Reduces time to manufacture Enlarges design possibilities Enhances communication and promotes

innovation in design teams

Summary

The design process Concurrent engineering Design for Manufacture Failure Modes and Effects Analysis Value analysis Quality Function Deployment (QFD)