s.dharani kumar asst.professor department of mechanical ... · s.dharani kumar asst.professor...
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S.DHARANI KUMAR
Asst.professor
Department of MechanicalEngineering
UNIT-1FUNDAMENTALS OF COMPUTER
GRAPHICS –PRODUCT CYCLE
DHARANI KUMAR.S/AP/MECH/SECE
CAD can be defined as the use of computer systems to perform certain
functions in the design process.
CAM is the use of computer systems to plan, manage and control the
operations of manufacturing plant through either direct or indirect computer
interface with the plant’s production resources.
DHARANI KUMAR.S/AP/MECH/SECE
The Product Cycle and CAD/CAM
• In order to establish the scope and definition of CAD/CAM in an
engineering environment and identify existing and future related tools,
a study of a typical product cycle is necessary. The following Figure
shows a flowchart of such a cycle.
DHARANI KUMAR.S/AP/MECH/SECE
The Manufacturing Process
The Design Process
SynthesisAnalysis The CAD Process
The CAM Process
Designneeds
Designdefinitions,specifications,and requirements
Collectingrelevant designinformation andfeasibility study
Designconceptualization
Designmodeling andsimulation
Designanalysis
Designoptimization
Designevaluation
Designdocumentation andcommunication
Processplanning
Ordermaterials
Design andprocurement ofnew tools
Productionplanning
NC, CNC, DNCprogramming
ProductionQualitycontrol
Packaging
Marketing
Shipping
Typical Product Life Cycle
DHARANI KUMAR.S/AP/MECH/SECE
• The product begins with a need which is identified based on customers'
and markets' demands.
• The product goes through two main processes from the idea
conceptualization to the finished product:
1. The design process.
2. The manufacturing process.
The main sub-processes that constitute the design process are:
1. Synthesis.
2. Analysis.DHARANI KUMAR.S/AP/MECH/SECE
The phases in design orGeneral design
procedure defined byShingley model
DHARANI KUMAR.S/AP/MECH/SECE
SHIGHELY ModelStep 1 Recognition of NeedProblems in the existing products or potential for
new products in the market have to be identified.Step 2 Definition of problemThe problem in the existing products or specification
of the new product is specified as “Design Brief”.It includes the specification of physical and functional
characteristics, cost, quality, performancerequirements etc
DHARANI KUMAR.S/AP/MECH/SECE
Step 3 Synthesis• In this stage the designer develops number of designs
to meet the requirement of design brief.Step 4 Analysis and optimization• Each design from the synthesis stage is analyzed and
the optimum one is selected.• Based on the analysis, improvements are made and
redesigned.
DHARANI KUMAR.S/AP/MECH/SECE
Step 5 EvaluationIn this stage, optimized design from the previous
stage is checked for all specifications mentioned in the“Design Brief”.• Performance• Quality• Reliability• And other aspects of productStep 6 Presentation• After the product design passing through the evaluation
stages, drawings, diagrams, materials specification,assembly lists, bill of materials etc.
DHARANI KUMAR.S/AP/MECH/SECE
Morphology of design• Morphology design refers the study of the chronological
structure of design projects. It is defined by seven phases andtheir sub steps.
Phase 1 Feasibility study / Conceptual design• To determine whether the need is original and valid.Phase 2 Preliminary design / Embodiment design• A surviving solution is tentatively accepted for further
examination• Synthesis are initiated the major design parameters must be
controlled• To maintained tolerances• Need customer feedback• testing
DHARANI KUMAR.S/AP/MECH/SECE
Morphology of designPhase 3 Detailed design• To prepare major layout• Deciding various dimensions of components• Preparing specification• Testing the prototype and redesign
Phase 4 Planning the production process• To prepare the detailed process planning sheets• Design of tool and fixture• Planning for the quality control system• Planning for the production personnel• Planning for the production control• Planning for the information flow feedback system
DHARANI KUMAR.S/AP/MECH/SECE
Morphology of designPhase V Planning for distribution• After the production of products, the products have to be
distributed• Design the packaging of the product• Planning the ware housing system• Planning for promotional activityPhase VI Planning for consumption• Design for maintenance• Design for reliability• Design for safety• Design for convenience use• Design for economic operation
DHARANI KUMAR.S/AP/MECH/SECE
Morphology of design
Phase VII Planning for Retirement• Design to reduce the rate• Design for the physical life to match• Design the product so that reusable materials
DHARANI KUMAR.S/AP/MECH/SECE
Pahl and Beitz Model
1. Classification of Task2. Conceptual Design3. Emodiment design4. Detail designStep 1 Classification of task• This phase involves the collection of information about the design
requirements and the constraints on the design as well as describing the asdesign specification
DHARANI KUMAR.S/AP/MECH/SECE
Step 2 Conceptual design• This phase involves the establishment of function to
be included in the design, and identification anddevelopment of suitable solution
Step 3 Emodiment design• In this phase, the conceptual solution is developed in
more detail, problems are resolved and weak aspectsare eliminated
Step 4 Detailed design• In this phase, dimensions, tolerances, materials and
form of each individual components of the design arespecified in detail which will be useful ormanufacturing
DHARANI KUMAR.S/AP/MECH/SECE
Ohsuga Model
• Ohsuga describes the design as a series of stages progressing fromrequirements through the conceptual design and preliminary designto detail design.
• If the proposal is unsuitable, then it is remodified.
DHARANI KUMAR.S/AP/MECH/SECE
Earle Model
The step in the design process prepared by Earle
• Problem Identification can be one of the following two general types
Identification of design need – It is the beginning point of the designprocess
Identification of design criteria – It is the part of problemidentification where the designer conducts an in depth investigationof specification which must be met by a new design.
DHARANI KUMAR.S/AP/MECH/SECE
Problem Identification• Problem statement – It is written to begin the thinking
process. This statement should be complete• Problem requirement- Needs to be positive requirement
are listed must be achieved through a proper design.• Problem limitations – Negative factors are listed.• Sketches- To generate 2D or 3D model• Gather data – The gathered data should be graphed or
easy interpretation
DHARANI KUMAR.S/AP/MECH/SECE
Preliminary ideas
• Conduct brain storming session – To find out a specific problem forall ideas contribute by its members
• Prepare sketches and notes - It can be used for create, modifyingand developing.
• Research existing designs – It can be obtained through research ofsimilar products, Magazines etc.
• Conduct survey – It can used to gather opinions and reactions.
DHARANI KUMAR.S/AP/MECH/SECE
Earle Model
Design refinement• Several of better preliminary
ideas are selected for suitablerefinement.
Analysis• To determine the cost, function
and market appeal.
DHARANI KUMAR.S/AP/MECH/SECE
Earle Model
Decision• At this stage a single design is
accepted as solution to thedesign problem when compareto the cost of manufacturing ,weight etc.
Implementation• It is the presentation of the
final design concept in workableform as working drawings andspecifications
DHARANI KUMAR.S/AP/MECH/SECE
Concurrent Engineering
Is a strategy where all the tasks involved in product development are done inparallel.
Collaboration between all individuals, groups and departments within a company.• Customer research• Designers• Marketing• Accounting• Engineering
DHARANI KUMAR.S/AP/MECH/SECE
Concurrent Engineering
Traditional Process = Linear
Vs
Concurrent Engineering = Team collaboration
DHARANI KUMAR.S/AP/MECH/SECE
Concurrent engineering
Characteristics of concurrentengineering• Product responsibilities lie on
the team of multi disciplinarygroup.
• Integration of design, processplanning and production will beachieved.
• Product lead time will be less.
Advantages of concurrent engineering• As the design decisions are taken
by a team of multidisciplinaryexperts, changes andmodification on the productdesign will be faster
• It ensures better quality
DHARANI KUMAR.S/AP/MECH/SECE
Sequential Engineering
• Three major phases of conventional manufacturing process aredesign, process planning and manufacturing.
• In design phase of the conventional manufacturing process, theproduct is designed on the basis of specification/requirements andmethod of manufacturing decided.
DHARANI KUMAR.S/AP/MECH/SECE
Sequential Engineering
Sequential engineeringapproach
Errors changes and corrections
DHARANI KUMAR.S/AP/MECH/SECE
Sequential Engineering
Advantages• It is very simple, well defined
method and allows everyone toremain on the same page.
• It is an enforced disciplineapproach
Disadvantages• As the decisions are taken by
individuals, productmodifications/changes will be slow.
• Since each activity is sequentiallycarried out, this approach requireslonger lead time
• Because of above reasons, theproduct will be low
DHARANI KUMAR.S/AP/MECH/SECE
Comparison b/w concurrent engineering and sequentialengineering
Design Planning Manufacture Testing Service
DHARANI KUMAR.S/AP/MECH/SECE
Roles of CAD in Design
• It is accurately generated and easily modifiable graphical representation of theproduct.
• The user can nearly view the actual product on screen.• It performs the complex design analysis in short time. By implementing finite
element analysis ( FEA) methods• Static, dynamic and natural frequency analysis
Heat transfer analysis Plastic analysis Fluid flow analysis Motion analysis Tolerances analysis Design optimization
DHARANI KUMAR.S/AP/MECH/SECE
CAD PROCESS
• The computer can be beneficially used in the design process.• Geometric modelingWire frame modelingSurface modelingSolid modeling
• Engineering analysis• Design review and evaluation• Automated drafting
DHARANI KUMAR.S/AP/MECH/SECE
Geometric modeling
Geometric modeling• The mathematical description should
be such that The image of the object can be
displayed and manipulated inthe computer terminal.
The modification on thegeometry of the object can beeasily done
It can be stored in thecomputer memory and it canalso be retrieved back .
Types of commands
• Commands used to generate basicgeometric entities such as points,lines, circles etc.
• Command used to do manipulationwork such as scaling, translation,rotation etc.
• Commands used for Booleanoperation to form the image of theobject in the computer screen
DHARANI KUMAR.S/AP/MECH/SECE
Geometric modeling
Engineering analysis• The computer can be used to aid
the analysis work such as stress– strain analysis, heat transferanalysis etc.
• The two types of importantengineering analysis are asfollowsAnalysis for mass propertiesFinite element analysis
Design Review and Evaluation• The accuracy of the design can be
checked and rectified if it isrequired in the computer screenitself.
• Another review features availablein the modeling software are“interference checking”
• The dimensions of the mating partscan be checked
DHARANI KUMAR.S/AP/MECH/SECE
Automated drafting
• Automated drafting is the process of crating hard copies of design drawing.• The important features of a drafting software• Automated dimensioning• Scaling drawing• Generating sectional views
Orthographic viewOblique viewIsometric viewPerspective view
• Enlargement of minute part details
DHARANI KUMAR.S/AP/MECH/SECE
Application of CAD
• Mechanical engineering sector is the largest user of CAD system• Manufacturing and forming a CAD/CAM• The application cover all types of manufacturing operationsMillingTurning,Punching etc
DHARANI KUMAR.S/AP/MECH/SECE
Application of CAD
Civil engineering• Projects• Interior design• Static and dynamic analysis
Electrical and electronics engineering• Electric motor• PCB design• IC design etc.
DHARANI KUMAR.S/AP/MECH/SECE