Introduction to CAD (MEC435)

Introduction to Computer-Aided Design (MEC435)

• This course introduces Computer-Aided Design (CAD).
• Key objectives include understanding various manufacturing spheres where computers are used.
• The course will also cover the product cycle, differences between conventional and computer-based manufacturing systems.
• Definitions of various computer-based applications will be provided.
• Topics include Computer-Aided Design (CAD) and its applications, various types of manufacturing organizations, and Computer-Aided Manufacturing (CAM).
• The course will also examine Computer-Integrated Manufacturing (CIM).

Objectives (MEC435)

• Understand various manufacturing spheres where computers are used.
• Define the product cycle and contrast conventional and computer-based manufacturing systems.
• Define computer-based applications.
• Explore CAD and its applications.
• Identify different manufacturing organizations.
• Learn about CAM and its applications.
• Understand the concept of Computer-Integrated Manufacturing (CIM).

Computer-Aided Environment

• Computers are crucial in daily life.
• CAD/CAM are widely used in engineering for drafting, design, simulation, analysis, and manufacturing.

Current Trends (2015)

• Trends with above-average adoption show awareness translating to usage.
• Trends with below-average adoption highlight awareness as insufficient for driving use.
• Awareness alone is not sufficient for usage.

Computer-Aided Environment Evolution

• Historical development of CAD, from tape systems and processors to magnetic cassette, floppy disks, and mainframe computers. This illustrates how technology evolved with stages of development.

Role of Computers in Manufacturing

• Computers in manufacturing are broadly categorized into two groups:
  • Computer monitoring and control of the manufacturing process.
  • Manufacturing support applications related to preparations and post-production operations.

Computer Aided Processes

• CAD: computer aided design
• CADD: computer aided design and drafting
• CAE: computer aided engineering
• CAM: computer aided manufacturing
• CAPP: computer aided process planning
• CATD: computer aided tool design
• CAP: computer aided planning

Areas of CAE

• Stress analysis using FEA (Finite Element Analysis)
• Thermal and fluid flow analysis (CFD)
• Mechanical event simulation (MES)
• Analysis tools for casting, molding, and die press forming
• Optimization of the product or process

Advantages of CAE

• Reduce product development cost and time
• Precise analysis and simulations
• Early prediction of results
• Design verification, eliminating the need for physical prototypes
• Minimize optimization time
• Parallel tasks during design stages

Manufacturing Production Types

• Mass production (e.g., automobiles)
• Batch production (e.g., industrial machinery, aircrafts)
• Job shop production (e.g., prototypes, aircrafts)

Manufacturing Engineering

• Process planning
• Process sheets
• Route sheets
• Tooling (cutting tools, jigs, fixtures, dies, moulds)
• CNC part programs
• Robot programs
• Inspection (CMM) programs
• Production organization
• Bill of materials
• Material requirement
• Planning
• Shop floor control
• Plant simulation
• Marketing and distribution
• Packaging
• Distribution
• Marketing

Advantages of CAM

• Greater design freedom
• Increased productivity
• Greater operating flexibility
• Shorter lead time
• Improved reliability
• Reduced maintenance
• Reduced scrap and rework
• Better management control

Computer Aided Engineering (CAE)

• Utilizing information technology to support engineers in analysis, simulation, design, manufacturing, planning, diagnosis, and repair. Offers tools to analyze components and assemblies like robustness, performance, and simulation.

Areas of CAE (Continued)

• Stress analysis
• Thermal and fluid flow analysis (using CFD)
• Kinematics
• Mechanical event simulations

Advantages of CAE (Continued)

• Reduced product development cost/time
• Precise analysis and simulations
• Early prediction of results
• Design verification without physical prototypes
• Optimization time reduction
• Parallel task execution

2D Drafting Tools

• Earliest CAD systems replace traditional design on drawing boards.
• Use simple geometric entities (lines, circles, arcs, curves, points) for annotations.
• Include dimensions, tolerances, and cross-hatching.
• Improve productivity over manual drawing techniques.
• Primarily used for documentation rather than design.
• Difficult to model complex 3D shapes.

3D Wireframe

• Extending 2D drafting into 3D provides improved visualization.
• Allows various viewpoint and rotation of models.

3D Wireframe (Limitations)

• Primarily uses lines, circles, arcs, curves, points to represent edges/vertices without surface information.
• Lacks understanding of object properties, unable to represent object faces between edges.
• Limited use for manufacturing.

Surface Modelling

• Fully defines external shape with faces, edges, vertices.
• Uses mathematical functions for surfaces.
• Created by fitting smooth skin through wireframes.
• Enables modelling of car parts, aircraft skins, and injection-moulded plastic items.
• CAD surface data can generate tool paths for CNC machinery.
• Limitations: does not model internal shapes.

Solid Modelling

• Most comprehensive CAD representation.
• Represents external and internal structures.
• Used to calculate part weight, center of gravity, and inertia moments.
• Combines basic shapes (primitive parts) from a library or creates them from wireframes/2D images.

Solid Modelling (Continued)

• Utilizes Boolean operations (union, intersection, difference, subtraction) to create more complex shapes.
• Data can be used directly for manufacturing, FEA, and dynamic analyses.
• Highly efficient CAD representation with thoroughness, accuracy and versatility.

Computer-Aided Manufacturing (CAM)

• The connection between product design and its manufacturing.
• Traditional approach uses engineering drawings to communicate design intent (tolerances, surface finish, materials, standard parts).
• Manufacturing process plans are made from drawings to control and program manufacturing tools.

CAM - In an Integrated CAD/CAM environment:

• CAD geometry is converted to CAM to facilitate manufacturing planning.
• Tool paths are generated for CNC machining tools for manufacturing parts.

Computer-Aided Engineering (CAE)

• Kinematics: Analyzing the movement of CAD assembly model parts and joints, and potential clashes/blockages.
• Finite Element Analysis (FEA): Numeric method for tackling complex engineering problems to assess stress/strain in components. Includes subdividing geometries into smaller elements, applying loads/boundary conditions, analyzing, and interpreting results.

CAE - FEA (Steps and Integrated Environment)

• CAD geometry is introduced to a finite element preprocessor to build models.

CAE

• Integrated CAD/CAM/CAE aids product introduction processes, reduces costs and lead times, and reuses product geometry.
• Traditional product development is sequential (design, manufacture, stress testing, etc.).

Engineering Approach: Sequential and Concurrent Approaches

• Sequential approach: Keeps strict control over product development; Later design issues may become expensive.
• Concurrent approach: Teams composed of various specialists work collaboratively throughout the design process.

Product Development Processes: Sequential vs. Concurrent

• Sequential: Linear, step-by-step approach; different steps, phases
• Concurrent (set-based): Integrated design process; continuous refinement

Model-Centered Engineering Design

• Shares a 3D CAD database.
• Eliminates the need for separating processes.
• Non-linear processes bring all input, process stages, and output data together.
• Enables better products, higher quality, reduced issues, and shorter development time.

This quiz tests your knowledge on Computer-Aided Design (CAD) and its related concepts covered in MEC435. You will explore the role of CAD in various manufacturing spheres, the product cycle, and the differences between conventional and computer-based systems. Prepare to assess your understanding of Computer-Aided Manufacturing (CAM) and Computer-Integrated Manufacturing (CIM).