chapter 10 managing engineering design
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Chapter 10 Managing Engineering Design. Advanced Organizer. Chapter Objectives. Describe the phases or stages in systems engineering and the new product development process Recognize product liability and safety issues Recognize the significance of reliability and other design factors. - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 10
Managing Engineering Design
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D ecision Mak ing
P lanning
O rganizing
Leading
C ontro lling
Managem ent Functions
R esearch
D esign
Production
Q uality
Marketing
Project Managem ent
Managing Technology
Tim e Managem ent
E thics
C areer
Personal Technology
Managing Engineering and Technology
Advanced Organizer
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Chapter Objectives
• Describe the phases or stages in systems engineering and the new product development process
• Recognize product liability and safety issues
• Recognize the significance of reliability and other design factors
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Nature of Engineering Design
Eng. Design Process
Information: • Statement of the problem• Design standards• Design methods
Information: • Drawings• Specifications• Financial estimates• Written reports• Oral presentations
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Systems Engineering/
New Product Development The design of a complex engineered system, from the realization of a need through production to engineering support in use is known as systems engineering (especially with military or space systems) or as new product development (with commercial systems).
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New Product Development - Stages
• Conceptual • Technical Feasibility or Concept Definition• Development• Commercial Validation• Production• Product Support• Disposal Stage
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Systems Engineering Process(In each phase of development)
• Requirements Analysis: Analyze customer needs, objectives, and constraints to determine the functional requirements.
• Functional Analysis/Allocation Identify lower level functions needed to meet these functional requirements, and translate them into design requirements suitable as design criteria.
• Synthesis. Define the system concept, configuration item alternatives and select the preferred set of product or process solutions to the level of detail required in the phase being conducted.
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Systems Engineering Process(In each phase of development)
• System Analysis and Control. Provide the progress measurement, assessment, and decision mechanisms required to evaluate design capabilities and document the design and decision data. – Trade-off (trade) studies– Risk management– Configuration management– Interface management – Systems engineering master schedule (SEMS) – Technical performance measurement (TPM) – Technical (design) reviews
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Quality Function Deployment (QFD)
• Quality function deployment is a team-based management tool in which the customer expectations are used to drive the product development process.
• Conflicting characteristics or requirements are identified early in the QFD process and can be resolved before production.
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Quality Function Deployment (QFD)
Key benefits:
• product improvement,
• increased customer satisfaction,
• reduction in the total product development cycle, &
• increased market share.
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Interrelationshipbetween
Technical Descriptors
How: Technical Descriptors(Voice of the Organization)
Relationship betweenRequirements and Descriptors
Prioritized Technical Descriptors
Pri
ori
tize
d
Cu
stom
er
Req
mts
Wh
at:
Cu
sto
me
r R
eq
mts
(Vo
ice
of
Cu
sto
me
r)
QFD: House of Quality
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4 Phases of QFD
Phase I:Productplanning
Phase II:Partsdeployment Phase III:
Processplanning
Phase IV:Productionplanning
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Classical Model of QFD
Production Operations
Process Parameters
Process Design Matrix
Process Parameters
Piece/Part Characteristics
Piece/Part Design Matrix
Piece/Part Characteristics
Tech. Performance Measures
Subsystem Design Matrix
HowWhatMatrix
Voice of CustomerHouse of Quality
Tech. Performance Measures
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Customer Needs •Good image•Easy to transport•Keeps present. flowing•Image visible in bad conditions•Minimizes unplanned interruptions•Design makes the product attractive•Device sets up quickly•Works well for short present.
PHASE I QFD -- Portable Slide ProjectorEngineering Metrics
Customer Requirements Cu
sto
mer
Weig
hts
Bri
gh
tness
Weig
ht
Dim
en
sion
s (g
irth
+ w
idth
)
Tim
e/T
ask
s re
qu
ired
to s
tart
pre
sen
tati
on
Dis
tort
ion
Dis
tan
ce f
rom
pre
sen
ter
(wit
h 3
' x 3
' p
roje
cti
on
)
Tim
e t
o i
nse
rt/p
ull
-ou
t sl
ide
Att
racti
ve p
rod
uct
Good image 9 9 9Easy to transport 9 9 9Device sets up quickly 9 3 1 9 3 3Works well for short present. 9 1 3 3 3Keeps present. flowing 1 3 3 9Image visible in bad conditions 3 9 3Minimizes unplanned interruptions 1 3 1 9Design makes the product attractive 3 3 3 9
Raw score
10
8
11
7
10
8
11
4
90
58
72
27
Relative Weight 1
6%
17
%
16
%
16
%
13
%
8%
10
%
4%
Engineering Metrics•Brightness•Weight•Dimensions (girth + width)•Time/Tasks required to start •Distortion•Distance from presenter •Time to insert/pull-out slide•Attractive product
QFD Example:Portable Slide Projector
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QFD Example:Portable Slide Projector—
Phase I
Customer RequirementsGood image
Easy to transportDevice sets up quicklyWorks well for short present.Keeps present. flowingImage visible in bad conditionsMinimizes unplanned interruptionsDesign makes the product attractive
Cu
sto
mer
Weig
hts
99991313
Engineering Metrics
Bri
ghtn
ess
Weig
ht
Dim
ensi
ons
Tim
e/T
ask
s
Dis
tort
ion
Dis
tance
Tim
e t
o inse
rt/p
ull
Att
ract
ive p
rod
uct
9 99 93 1 9 3 3
1 3 3 33 3 9
93 1 9
3 3 9
Raw score
10
8
11
7
10
8
11
4
81
58
72
27
Relative Weight 1
6%
17
%
16
%
17
%
12
%
8%
11
%
4%
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QFD Example:Portable Slide Projector—
Phase IIPart Characteristics
Top c
ase
Bott
om
case
Lens
Condense
r
Sta
nd
Heat
sink
Lam
p
Engineering MetricsBrightnessWeight
Dimensions (girth + width)Time/Tasks required to start pres.
DistortionDistance from presenterTime to insert/pull-out slideAttractive product
Ph
ase I
R
ela
tive
Weig
hts
16%17%16%16%13%8%10%4%
9 9 1 99 9 1 1 39 9 3 9 1 3 3
3 39 9 1 19 9 9
3 19 9 9
Raw score 3
.6
3.3
4.4
4.9
1.1
1.3
2.7
Rel. Weight 1
7%
15
%
21
%
23
%
5%
6%
13
%
Rank 3 4 2 1 7 6 5
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Phases in Systems Engineering /
New Product Development (DoD)
• Pre-milestone zero studies• Concept exploration & definition• Demonstration and validation• Engineering and manufacturing
development• Production and deployment• Operations and support
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Phases in Systems Engineering /
New Product Development (NASA)
• Conceptual design studies• Concept definition• Design and development• Fabrication, integration, test, and
certification• Pre-operations• Operations and disposal
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Phases in Systems Engineering / New Product Development
(NSPE/NIST )
• Conceptual• Technical feasibility• Development• Commercial validation and production
preparation• Full-scale production• Product support
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• Approval to expend the resources / agreement on the work to be accomplished.
• Accomplishment of the work • Compile the results: designs and
specifications, analyses and reports, and a proposed plan for conducting the following phase if one is recommended. – To cancel the development, – To go back (recycle) and do more work in the
present phase; or – To proceed with the next phase.
Tasks Within Each Phases of Systems Eng. / New Product
Development
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Conceptual stage
• Statement of the design problem, clearly defining what the desired intended accomplishment of the desired product
• Key functions • Performance characteristics• Constraints • Criteria of judging the design quality
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Conceptual stage
• Musts: requirements that must be met• Must nots: constraints defining what the
system must not be or do• Wants: features that would significantly
enhance the value of the solution but are not mandatory (to which an additional, even less compelling category of "nice to have" is often added)
• Don't wants: characteristics that reduce the value of the solution
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Conceptual stage(Kano’s Model)
Actual Performanc
e
Customer Satisfaction
SatisfiersDissatisfiers
Delighters
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Conceptual stage(Kano’s Model)
Product is non-conformantProduct conforms to std.
Product is unsafeProduct is safe to use
Function not providedNormal function
Missing instructionClear instruction
Broken partsAll parts work
Scratches, blemishesSmooth Surface
DissatisfiersExpected Quality
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Conceptual stage (Kano’s Model)
LargerTBTransactions /secondSpeed
LargerTBMTBFReliability
SmallerTBDollarsPrice
LargerTBCubic feet of storageCapacity
Direction
Performance Measure
Desired Quality
Satisfiers:
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Conceptual stage(Kano’s Model)
Examples of Delighters• Sony Walkman• 3M Post-it• Cup Holder• One-touch recording• Redial button on telephone• Graphic User Interface (GUI)
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Results from Conceptual stage
• A set of functional requirements• Identification of the potential barriers to
development, manufacturing, and marketing the proposed product.
• Test-of-principle model to reduce technical uncertainties
• Order-of-magnitude economic analyses and • Preliminary market surveys to reduce
financial uncertainty.
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Importance of Conceptual stage
• 1% of the cost of the product• 70 % of the life-cycle cost
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Technical feasibility stage
The objectives of this stage are • To confirm the target performance of the
new product through experimentation and/or accepted engineering analysis and
• To ascertain that there are no technical or economic barriers to implementation
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Technical feasibility stage
• Subsystem identification• Trade-off studies• System integration• Interface definition• Preliminary breadboard-level testing • Subsystem and system design requirements (reliability,
safety, maintainability, and environmental impact).• Development of preliminary test plans, production
methods, maintenance and logistic concepts, and marketing plans.
• Preliminary estimation of the life-cycle cost of the system.
• Preparation of a proposal for the development stage
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Importance of Technical feasibility stage
• 7% of the cost of the product• 85 % of the life-cycle cost
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Development stage (Build-test-fix-retest
sequences)The objective of this stage is • To make the needed improvements in
materials, designs and processes and • To confirm that the product will perform as
specified by constructing and testing engineering prototypes or pilot processes.
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Commercial validation and Production preparation stage
The objective of this stage is to develop the manufacturing techniques and establish test market validity of the new product.
• Selecting manufacturing procedures, production tools and technology, installation and start-up plans for the manufacturing process, and
• Selecting vendors for purchased materials, components, and subsystems.
Reproduction prototypes
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Full-scale production stage
• Final design drawings, specifications, flow charts, and procedures are completed for manufacture and assembly of all components and subsystems of the product, as well as for the production facility.
• Quality control procedures and reliability standards are established
• Contracts made with suppliers• Procedures established for product distribution and
support. • Manufacturing facilities are constructed• Continuous process improvement (kaizen)
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Product support stage
• Technical manuals for product installation, operation, and maintenance
• Training programs for customer personnel• Technical supports• Warranty services• Repair parts and replacement consumables must
be manufactured and distributed• New procedures for operation and maintenance• Improved parts for retrofit• Notification of product recall for safety reasons
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Disposal stage
• Every product causes waste during manufacture, while in use, and at the end of useful life that can create disposal problems.
• The time to begin asking, "how do we get rid of this" is in the early stages of product or process design.
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CONCURRENT ENGINEERING AND
CALS
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Traditional Product Development
• System Level Design• Subsystem Design• Component Design• Manufacturing Process Concept Development• Manufacturing Process Development• Delivery Development• Service Development• Delivery
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Concurrent Processes
System Level Design
Manufacturing Process Concept
Development
Delivery Development
Production & Delivery
Component Design
Subsystem Design Manufacturing
Process Development
Service Development
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Definition of Concurrent Engineering
A systematic approach to the integrated, concurrent design of products and their related processes, including manufacture and support.
This approach is intended to cause the developer, from the outset, to consider all elements of the product lifecycle from concept through disposal, including quality control, cost, scheduling, user requirements. (Inst. For Defense Analysis)
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Advantages of Concurrent Engineering
The set of methods, techniques, and practices that:• Cause significant consideration within the design
phases of factors from later in the life cycle;• Produce, along with the product design, the design
of processes to be employed later in the life of the product;
• Facilitate the reduction of the time required to translate the design into distributed products; and
• Enhance the ability of products to satisfy users' expectations and needs.
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CALS
• "Computer Aided Logistics Support," then • "Computer-aided Acquisition and Logistics
Support," • "Continuous Acquisition and Life-Cycle Support,"
(1993, DoD)• "Commerce At Light Speed" (U.S. industry)
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Purposes of CALS
To enable more effective generation, management, and use of digital data supporting the life cycle of a product through the use of international standards, business process change, and advanced technology application.
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CALS
Electronic storage, transmission, and retrieval of digital data
• Between engineers representing the several design stages,
• Between organization functions such as marketing, design, manufacturing, and product support, and
• Between cooperating organizations such as customer and supplier.
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Commercial standards
• Computer Graphics Metafile (CGM) (ISO-8632): A standard means of representing line drawings in a device-independent way.
• Electronic Data Interchange for Administration, Commerce, and Transport (EDIFACT) (ISO 9735, ANSI X12): An international standard means for communicating commercial (trade) information.
• Initial Graphics Exchange Specification (IGES) (ANSI Y14.26M): A standard means of representing product data in a device-independent way.
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Control Systems in Design
• Drawing/Design Release– Version Control– Product Data Management (PDM)
• Configuration (Design Criteria) Management– Functional baseline (at end of conceptual stage)– Allocated baseline (at end of validation stage)– Product baseline (at end of development stage)
• Design Review
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Special Considerations in Design
• Product liability • Safety• Reliability• Maintainability• Availability• Ergonomics• Producibility
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History of Product Liability
• Caveat emptor (let the buyer beware)• “Privity of contract” (Direct contractual relationship)• 1916, MacPherson v. Buick (No need for direct contract)• Plaintiff must prove negligence• 1960, Hernington v. Bloomfield Motors, implied
warranty• 1984, Greenman v. Yuba Power Product Strict
Liability• Absolute liability: “A manufacturer could be held strictly
liable for failure to warn of a product hazard, even if the hazard was scientifically unknowable at the time of the manufacture and sale of the product.”
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Reducing Liability
• Include safety as a primary specification for product design.
• Use standard, proven materials and components. • Subject the design to thorough analysis and testing.• Employ a formal design review process in which
safety is emphasized.• Specify proven manufacturing methods.• Assure an effective, independent quality control
and inspection process.• Be sure that there are warning labels on the
product where necessary.
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Reducing Liability
• Supply clear and unambiguous instructions for installation and use.
• Establish a traceable system of distribution, with warranty cards, against the possibility of product recall.
• Institute an effective failure reporting and analysis system, with timely redesign and retrofit as appropriate.
• Document all product safety precautions, actions, and decisions through the product life cycle.
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Designing for Reliability
Definition of Reliability:
• Reliability is the probability that a system
• Will demonstrate specified performance
• For a stated period of time
• When operated under specified conditions.
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Reliability Measures
• Reliability
0
tt S
SR
• Failure CDF (cumulative distribution function):
• Failure PDF (probability density function):
• Failure or hazard rate:
t
0 0S
FF(t)
0
t
S
Ff(t)
t
t
S
F(t)
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Simple Reliability Models
• Simple Parallel Model
)R)(R(R LST
S L
L
L
• Simple Series Model
2LT )R1(1R
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Simple Reliability Models
2L
2ST )R1(1)R1(1R
L
L
S
S
L
L
S
S
• Series- parallel model
2LST )R)(R(11R
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Infant Mortality
Useful Life Wear-out
Hazard Rate
Life
Simple Reliability ModelsBathtub curve
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Designing for Reliability
• “Start with the best”
• Redundancy
• Factor of safety
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Maintainability
• Maintainability is the probability that a failed system
• Will be restored to specified performance
• Within a stated period of time
• When maintained under specified conditions.
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Maintainability
Maintenance downtime• Administrative & preparation time• Logistic time• Active maintenance time
Types of Maintenance • Corrective maintenance• Preventive maintenance• Predictive maintenance
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Availability
• Inherent Availability (considers only corrective maintenance)
Ai = MTBF / (MTBF+MTTR)• Operational Availability (considers both preventive
& corrective maintenance)
Ao = MTBM / (MTBM+MDT)MTBM: Mean Time Between MaintenanceMDT: Mean Down TimeMTTR: Mean Time To RepairMTBF: Mean Time Between Failure (1/)BIT: Build-In Test
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Other Considerations
• Human Factors Engineering (Ergonomics)• Standardization
– Set of specifications for parts, materials, or processes intended to achieve uniformity, efficiency, and a specified quality.
• Producibility
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Value Engineering
A methodical study of all components of a product in order to discover and eliminate unnecessary costs over the product life cycle without interfering with the effectiveness of the product.
• What is it?• What does it do?• What does it cost?• What does it worth?• What else might do the job?• What do the alternatives cost?• Which alternative is least expensive?• Will the alternative meet the requirements?• What is needed to implement the alternative?