product design. lecture outline l the design process l concurrent engineering l design for...
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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
Nu
mb
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of D
esi
gn
Ch
ang
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)