S.DHARANI KUMAR Asst.professor Department of Mechanical ... · S.DHARANI KUMAR Asst.professor Department of Mechanical Engineering UNIT-1 FUNDAMENTALS OF COMPUTER GRAPHICS –PRODUCT

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.




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.


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


• 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



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


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.


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.


Design process


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



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


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


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




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


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



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.



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.



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


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.


Earle Model

Design refinement• Several of better preliminary

ideas are selected for suitablerefinement.

Analysis• To determine the cost, function

and market appeal.


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


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


Concurrent Engineering

Traditional Process = Linear

Vs

Concurrent Engineering = Team collaboration




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


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.



Sequential engineeringapproach

Errors changes and corrections



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


Comparison b/w concurrent engineering and sequentialengineering

Design Planning Manufacture Testing Service


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


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


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


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


CAD Process


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


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


Application of CAD

Civil engineering• Projects• Interior design• Static and dynamic analysis

Electrical and electronics engineering• Electric motor• PCB design• IC design etc.



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S.DHARANI KUMAR Asst.professor Department of Mechanical ... · S.DHARANI KUMAR Asst.professor Department of Mechanical Engineering UNIT-1 FUNDAMENTALS OF COMPUTER GRAPHICS –PRODUCT