CHAPTER 3 Computer-Aided Design and Drafting (CADD)

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Transcript of CHAPTER 3 Computer-Aided Design and Drafting (CADD)

  • CHAPTER 3Computer-Aided Design and Drafting (CADD)

  • Learning ObjectivesDefine CADD and CADDescribe the CADD workstation and peripheral equipmentIdentify common CADD software manufactures and productsDescribe and compare CADD formatsIdentify disciplines and industry concepts related to CADD

  • Learning ObjectivesExplain the use of animation and virtual reality in the design processDemonstrate an understanding of basic CADD techniques including drawing and editing, line standards and layers, reusing content, plotting, file templates, and storing and managing filesExplain basic surface and solid modeling techniques

  • Learning ObjectivesDemonstrate an understanding of parametric solid modelingIdentify, describe, and use national CADD standardsDiscuss issues related to productivity with CADDDescribe sustainable design and CAD practices

  • Computer-Aided Design and Drafting (CADD)Entire range of design and drafting with the aid of a computerComputer-aided design (CAD)Computer-aided drafting (CAD)Used by several industries and most engineering and architectural related disciplines

  • CADD WorkstationHardwareComputer provides:Data processingCalculationsCommunication with peripheral equipment

  • CADD Software ProductsNumerous and constantly changingMany CADD software manufacturesRapidly evolving CADD market

  • CADD Software ProductsGeneral-purposeMechanical computer aided design (MCAD)Other disciplines such as architectural, civil, structuralSoftware packagesProduct lifecycle management (PLM)

  • Common CADD Software Manufactures

  • Common CADD Formats2-D drawings3-D wireframe models3-D surface models3-D solid models

  • Choosing a CADD FormatDesign and drafting practicesProject requirementsCollaboration and communicationSoftware and training costsKnown industry standard productStability and usabilitySupport and trainingPersonal preference

  • Two-Dimensional (2-D) DrawingsEstablished and often required design and drafting formatCommon in all engineering and architectural industries and related disciplinesDescribes design intent and product requirementsCan provide computer numerical control (CNC) machine code

  • 2-D Drawings

  • Three-Dimensional (3-D) Wireframe ModelsBasic 3-D CAD modelInclude object edges and verticesCan provide geometry for:2-D drawings3-D computer numerical control (CNC) machine codeReplaced by 3-D surface and solid modeling

  • 3-D Wireframe Models

  • 3-D Surface ModelsInclude object edges, vertices, and surfacesComplex curves and formsCan provide geometry for:2-D drawings3-D solid models3-D computer numerical control (CNC) machine code

  • 3-D Surface Models

  • 3-D Solid ModelsMost complex CAD formatInclude object edges, vertices, surfaces, and massExact digital representation of a productMay require some surface modelingOffer engineering analysis and testingCan provide geometry for:2-D drawings3-D computer numerical control (CNC) machine code

  • 3-D Solid Models

  • Industry and CADDCADD can store many forms of dataCADD supports:ManufacturingMarketingSalesServiceMaintenance

  • Product Lifecycle Management (PLM)Supported by CADDPLM software helps coordinate:Design and manufacturingVisualization and presentationMaintenance and disassembly

  • Web-Based CollaborationCommon to modern design and draftingSupports the design and documentation processUses product data management (PDM) systemsAllows for increased outsourcing

  • Prototyping

  • Prototyping

  • Computer-Aided Engineering (CAE)

  • AnimationEngineering animationsBasic element of product design and analysiseLearning animationsAdditional classroom learning tool or an online or distance learning presentationEntertainment animationsMovies, television, and video games

  • Computer-Aided Manufacturing (CAM)Major innovationCommon processHelps produce consistent and quality productsComputer-aided design/computer-aided manufacturing (CAD/CAM)Computer numerical control (CNC)

  • Computer-Integrated Manufacturing (CIM)Computer and software controls most, if not all, portions of manufacturingIncorporates CAD, CAM, robotics, electronics, hydraulics, pneumatics, computer programming, and process control

  • Additional CADD Applications

  • Virtual Reality (VR)Allows one or more people to move and react in a computer-simulated environmentProvides interaction with a model during the design process Requires special interface devicesWalk-throughFly-through

  • VR Applications and DevicesThrough-the-window VR (passive VR)Head Mounted Display (HMD)Binocular Omni-Orientation Monitor (BOOM)Cave Automatic Virtual Environment (CAVE)Haptic InterfaceWeb-Enabled Virtual Reality Modeling Language (VRML)

  • Basic CADD TechniquesDrawing and EditingLine Standards and LayersReusing ContentPlottingFile TemplatesStoring and Managing Files

  • Drawing and EditingCommands for creating and modifying all elements of a drawingTechniques vary depending on:CADD softwarePreferred design techniques

  • Drawing and Editing

  • Line Standards and LayersHelp organize and assign properties to objectsSeparate objects into logical groups for formatting and display purposes

  • Line Standards and Layers

  • Example Mechanical Drafting Layers

    Layer NameLine TypeLine WeightColorObjectSolid (Continuous).02 in. (0.6 mm)BlackHiddenHidden (Dashed).01 in. (0.3 mm)BlueCenterCenter.01 in. (0.3 mm)GreenDimensionSolid (Continuous).01 in. (0.3 mm)RedConstructionSolid (Continuous).01 in. (0.3 mm)YellowBorderSolid (Continuous).02 in. (0.6 mm)BlackPhantomPhantom.01 in. (0.3 mm)MagentaSectionSolid (Continuous).01 in. (0.3 mm)Brown

  • Reusing ContentCADD offers the ability to reuse:Objects and object propertiesText and dimension settingsDrafting symbolsSheetsTypical drawing details

  • Plotting a Hard CopyOften requiredCreates a plot that can be viewed and marked without having a computerEach CADD system uses a specific method to plotPlotting theory is similarElectronic plotting (exporting)

  • Drawing Scale and Scale FactorImportant consideration when plottingAutomated by most CADD software,Remains an important conceptExample application:A 1:4 scale drawing has a scale factor of 4 (4 1 = 4)Multiply the scale factor of 4 by values such as text height of .12 in. (3 mm) to find the .48 in. (12 mm) scaled text height

  • File TemplatesPreset settings for specific applicationsStandard items required for multiple projectsSave timeImprove consistency

  • Common Elements of a File TemplateUnits settingsDrawing and design settings and aidsLayersColor, material, and lighting standardsAnnotation standardsCommon symbolsDisplay settingsSheets and sheet itemsPlot settings

  • Storing and Managing FilesSave files immediately after you begin workSave at least every 10 to 15 minutesDevelop an organized structure of file foldersUse a specific file naming systemFollow established file management techniques

  • Surface Modeling TechniquesPolygonal modelingSurfaces are quick and easy to modifyCommon for character design for gamesNURBSNon-uniform rational basis splineNon-uniform rational B-splineAccurate curves and surfacesUsed by most CAD systems

  • NURB GeometryComplex mathematical spline representation with control pointsChange control points to alter the curve

  • NURB Geometry

  • Direct Surface Modeling

  • Procedural Surface Modeling

  • Solid PrimitivesBoolean operationsAlso apply to more complex solid models

  • Feature-Based Solid ModelingConstruct solid models using intuitive feature toolsOften begins with a 2-D sketchSketch used to develop a sketched featureAdditional features add or subtract solid material

  • Parametric Solid ModelsMost common feature-based solid modelsOften store model historyHistory-based solid modelingCaptures design intent using parametersMaintains design constraints

  • History-Free Solid ModelingOften associated with basic solids (dumb solids)Makes design changes easyHelps support collaborationExplicit modeling

  • Parametric Solid Model Work EnvironmentsPartAssembly (subassemblies and assembly)

  • Part Model ElementsSketchSketched featurePlaced (built-in, added, automated) featuresFeature patternReference (work, reference geometry) featuresCatalog (library) feature

  • Assembly ModelingAdd and constrain existing componentsBottom-up designCreate components within an assembly file (in-place)Top-down designAssembly constraints (mates)

  • Assembly Modeling

  • Extracting Drawing Content from ModelsEditing the model adjusts the corresponding drawingSome edits to the drawing modify the linked model

  • CADD StandardsDesign and drafting requirementsAppearanceTechniqueOperating proceduresRecord keeping method

  • CADD StandardsFile storage, naming, and backupFile templatesUnits of measurementLayout characteristicsBorders and title blocksSymbolsLayers, and text, table, and dimension stylesPlot styles and plotting

  • CADD StandardsAmerican Society of Mechanical Engineers (ASME) standardsCADD Skill StandardsUnited States National CAD Standard

  • Design PlanningImportant and productive timeDetermines how you approach a projectWithout proper planning you may become frustrated and waste time

  • Design PlanningHelps establish:Drawing layoutDrafting settingsHow and when to perform specific tasksWhat objects and symbols to createThe best use of CADD and equipmentAn even workload

  • Ergonomic W