Introduction to cad cam

INTRODUCTION TO
CAD/CAM
ARVIND DESHPANDE

Need for CAD/CAM
 Design and manufacturing forms the core of engineering.
 To remain competitive in global economy
 New products with enhanced features at competitive
costs
 Short lead times and short product lives
 Reduction in product life cycle
 Mass customization – Customer specific changes to
satisfy diverse requirements – High flexibility in the
manufacturing system
 Reduction in manufacturing cost and delivery time
 Increasing consumer awareness about quality
3/6/2012 Arvind Deshpande(VJTI) 2

Developments in computers
 Developments in microelectronics –
microprocessors, VLSI
 Availability of computers with enhanced
memory and faster computing speed at
affordable prices
 Development of graphics workstations with
powerful graphic facilities
 Development of interactive graphics and
analysis software - Easy to use and powerful

Computer Aided Design
 Use of computer systems to assist in creation,
modification, analysis and optimization of a
design.
 Computer assistance while a designer
converts his or her ideas and knowledge into
a mathematical and graphical model
represented in a computer.


Computer Aided Manufacturing
 Use of computers systems to plan, manage and
control the operations of a manufacturing plant
through either direct or indirect computer interface
with plant’s production resources.
1. Computer monitoring and control - Computer is
connected directly to the manufacturing process
e.g. NC/CNC machines, chemical processing etc.
2. Manufacturing support applications – Use of
computers in process planning, scheduling, shop
floor control, work study, tool design, quality control
etc.

CAD-CAM and AUTOMATION
 Automation is technology concerned with the application of complex
mechanical, electrical, electronic , hydraulic, pneumatic or computer
based system in the operation and control of production.
 Types of manufacturing
1. Continuous process industries – Sugar industry, chemical industry etc.
2. Mass production industries – Automobiles, Consumer goods etc.
3. Batch production industries – machines, aircrafts etc.
4. Job production industries – Prototypes, heat exchangers , chemical
reactors etc.
 Automation is focused on reducing unit production time and to some
extent time associated with planning and setting up for each batch of
production.
 CAD/CAM is focused on reducing time for designing the product and all
other activities which are accomplished once for each product and time
associated with planning and setting up for each batch of production


CAD/CAM
 CAD/CAM involves all the processes of
conceptualizing , designing, analyzing,
prototyping and actual manufacturing with
computer’s assistance.
 Latest techniques of geometric modeling
(Feature base or parametric modeling) and
manufacturing like rapid prototyping (RP)
have bridged the gap between product
conceptualization and product realization.

CAD/CAM
 CAD/CAM - Key to improve manufacturing productivity
and the best approach for meeting the critical design
requirements.
 CAD/CAM software provides engineers with the tools
needed to perform their technical jobs efficiently and
free them from the tedious and time-consuming tasks
that require little or no technical expertise.
 CAD/CAM software speeds the design process,
therefore increasing productivity, innovation and
creativity of designers.
 CAD/CAM is the only mean to meet the new
technological design and production requirements of
increased accuracy and uniformity

Product life cycle
 2 main process: Design + Manufacturing
 2 sub-process of design: Synthesis + Analysis
 The end goal of the synthesis is a conceptual
design of the prospective product
 The analysis evaluate the performance of the
expected product
 Computer prototypes: Less expensive and faster
to generate


Product life cycle
 Manufacturing process begins with the
process planning.
 Process planning is the backbone of the
manufacturing process.
 The outcome of the process planning is a
production plan, tools procurement, material
order, and machine programming.


A typical
CAD process


A typical
CAM process


History of CAD/CAM
 4 major phases of development

 1950s: Start of interactive computer graphics,

 CRT (Cathode Ray Tube), NC (Numerical Control), APT (Automatically
Programmed Tools)

 1960s: Critical research period for interactive computer graphics

 Sketchpad by Ivan Sutherland, CAD 용어 사용 시작,

 Lockheed initiated CADAM,

 Storage tube-based turnkey system
 1970s: Potential of interactive computer graphics was realized by industry,
 SIGGRAPH, NCGA, IGES,

 Golden era for computer drafting,

 Wireframe modeling


History of CAD/CAM . . .
 1980s: CAD/CAM heady years of research,
 Integration, Solid modeling, synthetic curves and surfaces

 1990s: Management of CAD/CAM capabilities
 CIM, EDB, PDM, CALS, VR

 Improvement in communication medium and networking

 Reduced cost of hardware and software

 2000s: Wireless transmission, Reduced cost of high
performance computing, Reverse engineering - Rapid
prototyping


Definition of CAD tools based on constituents

Definition of CAD tools based on implementation

Definition of CAM tools based on constituents

Definition of CAM tools based on implementation

Factors that determine the success
of CAM implementation.

 The link between CAD and CAM must be a two-way route –
CAD databases must reflect manufacturing requirements
such as tolerances and features. Designers must think in
terms of CAM requirements when finalizing their designs.
CAD databases and their limitations must be conveyed to
manufacturing engineers who plan to utilize them in process
planning and other manufacturing functions.
 The hardware and software networking of the various CAM
elements - Timely synchronization among robots, vision
systems, manufacturing cells, material handling systems,
and other shop-floor tasks is most important.


Definition of CAD/CAM tools based on constituents

Definition of CAD/CAM tools
based on implementation

Conventional Design
Process


Comparison of capabilities of
designers and computers
 Human designers are good  Computers are good at
at 1. Carry out long, complex and
1. Identifying design needs laborious calculations
2. Drawing up specifications 2. Store and efficiently search
3. Selecting design variations large databases
4. Optimizing design solutions 3. Provide several alternative
5. Selecting the best design design solutions
6. Learning from experience 4. Provide information on design
methodologies, heuristic data
and stored expertise
5. Simulation of design for
optimization
6. Aids in modeling, drafting and
documentation

Concurrent Engineering
 New technique adopted to improve efficiency of
product design & reduce product cycle design time
 Team of people from different function areas
 Interaction between different departments
 Concurrent engg. (Simultaneous or parallel) vs
Sequential engg. (Across the wall method)
 Use of special methods like DFMA and FMEA
 Different departments can start their work
simultaneously
 Improve workflow
 Eliminates conflict and procedures


Concurrent Engineering
 Holistic approach to product development
 Robust products
 Reduction in lead time for product
development
 IT tools – CAD systems with solid modeling
capabilities, KBE, RDBMS, PLM, ERP


ADVANTAGES OF CAD

1. To increase the productivity of the designer
 Create conceptual design of product
 Better visualization – rotate and view the objects from various sides and directions,
display in several colours to appeal the customers, display all inner details of the
assembly
 Detail drawing, assembly drawing, BOM can be automatically generated.
 Reduction in design cost
 Shorter project completion time
 Editing or refining the model to improve aesthetics, ergonomics and performance
2. To improve quality of design
 Use of analysis tools such as FEM – stress analysis, vibration, CFD- thermal, fluid
analysis
 Mechanism analysis to check for interference or clearance between mating parts in
static or dynamic situations
 Large no.of alternatives can be investigated
 Greater accuracy in design calculations and reduction in errors
 Study the product from various aspects such as material requirements, cost, value
engineering, manufacturing processes, standardization, simplification, variety
reduction, service life, lubrication, servicing and maintenance aspects etc.

ADVANTAGES OF CAD
3. To improve communication
 Better visualization, greater legibility
 Standardization of design, drafting, documentation procedures
 Direct feed back from manufacturing, assembly, inspection and
other depts.
 Use of design data for analysis, drafting and documentation,
process planning, tool and fixture design, manufacturing,
inspection etc.
4. To create a database of parts
 Minimise product variations
 Parametric designs
 Making families of parts reducing tooling, fixturing and testing
costs


Computer Aided Engineering
 CAE is the technology concerned with the use of computer
systems to analyze CAD geometry, allowing the designer to
simulate and study how the product will behave.
 Mass property calculations (mass, centre of gravity, moment of
inertia etc.)
 Mechanical assembly testing (dimensional checking, interference
checking etc.)
 Kinematic analysis and animation (movement visualization,
simulation)
 FEM analysis (Linear static analysis, dynamic analysis, seismic
analysis, non-linear static analysis)
 Fluid analysis (CFD)
 Thermal analysis
 Vibration analysis


Computer Integrated
Manufacturing
 CAD-CAM CIM
 CIM – A process of integration of CAD, CAM and business aspects of a
factory. It attempts complete automation with all processes functioning
under computer control.
 It uses database and communication technologies to integrate design,
manufacturing and business functions.
 CIM stands for a holistic and methodical approach to activities of the
enterprise in order to improve the industrial performance.
 Reduces human component of manufacturing
 Lean manufacturing – Reduce waste at all stages of manufacturing.
(Toyota)
 Objectives of CIM –
1. Production improvement
2. Cost reduction
3. Fulfillment of delivery dates
4. Quality improvement
5. Global and local flexibility of manufacturing system


NEED TO STUDY CAD/CAM
 Training courses typically offered by CAD/CAM vendors & manuals and
documentation which are typically provided with the CAD/CAM systems
tend to concentrate on the user interface and the syntax associated
with it.
 Understanding the basic concepts and principles underlying the system
helps the user in understanding the various jargon and terminology
encountered in the system documentation as well as enabling the user
to deal with system errors more intelligently.
 Failure of such understanding often results in user frustration and a
significant decline in productivity and utilization of the system relative to
manual procedures.
 Learning one system is sufficient to learn another one at a faster pace.
 Learning the basic concepts does not only speed up the training curve
of users but it also helps them utilize the technology productively.


Syllabus
1. Introduction
 The design process, product life cycle & CAD/CAM, computer for design process.
2. Computer Aided Design
2.1 Introduction, functions of graphics package, graphics devices.
2.2 Scan conversion: - scan converting line, circle ellipse.
2.3 2D-3D Transformations.
2.4 2D clipping & viewing:-line clipping, polygon clipping.
2.5 Curves: - Introduction, parametric, non parametric curves, Hermite, Bezier, B-spline
Curves.
2.6 Surfaces: - Introduction, surface of revolution, sweep surfaces, bilinear surface,
Coons patch, Bezier Bspline surfaces.
2.7 Hidden surface elimination: - Introduction, Visibiliti techniques, z-buffer, painters
algorithm.
2.8 Solid Modeling:-Introduction, solid representation, B-rep, CSG schemes.
2.9 Graphics standards: - DXF, IGES, STEP


Syllabus
3. CAM
3.1 Fundamentals of NC, CNC, DNC, Basic components of
NC system, NC procedure, NC Co-ordinate system.
3.2 Introduction to NC part programming, Tape coding and
formatting, Manual part programming.
3.3 Introduction to computer aided part programming APT
language, Macro statement.
3.4 CMM & Rapid Prototyping,


References
 Text books
1. CAD/CAM – P.N.Rao, Tata McGraw Hill
2. CAD/CAM – Sareen and Grewal, S.Chand
3. CAD/CAM/CAE – Chougule N.K., Scitech
4. CAD/CAM – Groover
5. CAD/CAM/CIM - Radhakrishnan
6. Computer Graphics – Schaum series
 Reference books
1. CAD/CAM – Ibrahim Zeid
2. Computer graphics – Hearn and Baker

Introduction to cad cam

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Introduction to cad cam