Introduction of cad cam

COMPUTER
AIDED
DESIGN
AND
MANUFACTURING
BE, 7th Semester
CAD/CAM,VIKKY(RSRRCETBHILAI)

Computer Aided Design & Manufacturing (CAD/CAM)
Computer-aided design (CAD): CAD is the use of computer programs to
create two- or three-dimensional (2D or 3D) graphical representations of
physical objects. CAD software may be specialized for specific applications.
CAD is widely used for computer animation and special effects in movies,
advertising, and other applications where the graphic design itself is the
finished product. CAD is also used to design physical products in a wide
range of industries, where the software performs calculations for determining
an optimum shape and size for a variety of product and industrial design
applications.
In product and industrial design, CAD is used mainly for the creation
of detailed 3D solid or surface models, or 2D vector-based drawings of
physical components. However, CAD is also used throughout the engineering
process from conceptual design and layout of products, through strength and
dynamic analysis of assemblies, to the definition of manufacturing methods.
This allows an engineer to both interactively and automatically analyze design
variants, to find the optimal design for manufacturing while minimizing the
use of physical prototypes.

Computer Aided Manufacturing (CAM): 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. Computer Aided Manufacturing commonly refers to the use of
numerical control (NC) computer software applications to create detailed
instructions (G-code) that drive computer numerical control (CNC) machine
tools for manufacturing parts. Manufacturers in a variety of industries depend
on the capabilities of CAM to produce high-quality parts.
A broader definition of CAM can include the use of computer applications to
define a manufacturing plan for tooling design, computer-aided design (CAD)
model preparation, NC programming, coordinate measuring machine (CMM)
inspection programming, machine tool simulation, or post-processing. The
plan is then executed in a production environment, such as direct numerical
control (DNC), tool management, CNC machining, or CMM execution.

CAD/CAM (computer-aided design and computer-aided manufacturing)
refers to computer software that is used to both design and manufacture
products.
CAD is the use of computer technology for design and design documentation.
CAD/CAM applications are used to both design a product and program
manufacturing processes, specifically, CNC machining. CAM software uses
the models and assemblies created in CAD software to generate tool paths
that drive the machines that turn the designs into physical parts. CAD/CAM
software is most often used for machining of prototypes and finished parts.
CAD/CAM is 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, there fore 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.

Computer assistance, while a designer converts his or her ideas and
knowledge, into a mathematical and graphical model represented in a
computer.
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 FLOW CHART
Fig: Information flow chart in CAD/CAM Application

PRODUCT CYCLE
For the reader to appreciate the scope of CAD/CAM in the operations of a
manufacturing firm, it is appropriate to examine the various activities and
functions that must be accomplished in the design and manufacture of a
product. We will refer to these activities and functions as the product cycle. A
diagram showing the various steps in the product cycle is presented in Figure.
The cycle is driven by customers and markets which demand the product. It is
realistic to think of these as a large collection of diverse industrial and
consumer markets rather than one monolithic market. Depending on the
particular customer group, there will be differences in the way the product
cycle is activated in some cases, the design functions are performed by the
customer and the product is manufactured by a different firm.
In other cases, design and manufacturing is accomplished by the same firm.
Whatever the case, the product cycle begins with
concept, an idea for a product. This concept is cultivated, refined, analyzed,
improved, and translated into a plan for the product through
the design engineering process.

Fig: Product cycle (design and manufacturing)
The plan is documented by drafting Ii set of engineering drawings showing
how the product is made and providing a set of specifications indicating how
the product should perform.
Except for engineering changes which typically follow the product
throughout its life cycle, this completes the design activities in above figure.
The next activities involve the manufacture of the product.
Product
Concept
Design
Engineering
Drafting
Process
Planning
Production
Scheduling
Production
Quality
Control
Customer
& Market
Order New
Equipment
& Tooling

A process plan is formulated which specifies the sequence of production
operations required to make the product. New equipment and tools must some
times be acquired to produce the new product. Scheduling provides a plan that
commits the company to the manufacture of certain quantities of the product
by certain dates. Once all of these plans are formulated,
the product goes into production, followed by quality testing, and delivery to t
he customer.
The impact of CAD/CAM is manifest in all of the different activities in
the product cycle, as indicated in Figure. Computer-aided design and
automated drafting are utilized in the conceptualization, design and
documentation of the product. Computers are used in process planning and
scheduling to perform these functions more efficiently.
Computers are used in production to monitor and control the
manufacturing operations. In quality control, computers are used to perform
inspections and performance tests on the product and its components.
As illustrated in Figure, CAD/CAM is overlaid on virtually all of the activities
and functions of the product cycle.

In the design and production operations of a modem manufacturing firm, the
computer has become a pervasive, useful, and indispensable tool. It is
strategically important and competitively imperative that manufacturing firms
and the people who are employed by them understand CAD/CAM
Computer
aided design
Computer automated
drafting &
documentation
Computer aided
process planning
Product
concept
Customer
& Market
Quality
Control
Computer
aided quality
control
Computer controlled
robots, machines, etc.
Computer scheduling,
material requirements
planning, shop floor control
Production Scheduling
Process
planning
Order new
equipment &
tooling
Design
Engineering
Drafting
Fig: Product cycle revised with CAD/CAM overlaid

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.
Typical Product Life Cycle
The Manufacturing Process
The Design Process
Synthesis
Analysis The CAD Process
The CAM Process
Design
needs
Design definitions,
specifications, and
requirements
Collecting
relevant design
information and
feasibility study
Design
conceptualization
Design
modeling and
simulation
Design
analysis
Design
optimization
Design
evaluation
Design documentation
and communication
Process
planning
Order
materials
Design and
procurement of
new tools
Production
planning
NC, CNC, DNC
programming
Production
Quality
control
Packaging
Marketing
Shipping

CAD Tools Required to Support the Design Process
Design phase Required CAD tools
Design conceptualization Geometric modeling techniques; Graphics
aids; manipulations; and visualization
Design modeling and simulation Same as above; animation; assemblies;
special modeling packages.
Design analysis Analysis packages; customized programs
and packages.
Design optimization Customized applications; structural
optimization.
Design evaluation Dimensioning; tolerances; BOM; NC.
Design communication and
documentation
Drafting and detailing…

Manufacturing phase Required CAM tools
Process planning CAPP techniques; cost analysis;
material and tooling specification.
Part programming NC programming
Inspection CAQ; and Inspection software
Assembly Robotics simulation and
programming
CAM Tools Required to Support the Design Process

PRODUCTENGINEERING
It is to the process of designing and developing a device, assembly, or system
such that it be produced as an item for sale through some production
manufacturing process. Product engineering usually entails activity dealing
with issues of cost, productivity, quality, performance, reliability,
serviceability and user features. These product characteristics are generally
all sought in the attempt to make the resulting product attractive to its
intended market and a successful contributor to the business of the
organization that intends to offer the product to that market. It includes
design, development and transitioning to manufacturing of the product. The
term encompasses developing the concept of the product and the design and
development of its mechanical, electronics and software components. For
example a product like a digital camera would include defining the feature
set, design of the optics, the mechanical and ergonomic design of the
packaging, developing the electronics that control the various component and
developing the software that allows the user to see the pictures, store it in
memory, download to a computer, etc. After the initial design and
development is done, transitioning the product to manufacture it in volumes
is considered part of product engineering. Product engineering is
an engineering discipline that deals with both design
and manufacturing aspects of a product.

BENEFITS of CAD/CAM
Benefits of CAD
The benefits of CAD include lower product development costs, increased
productivity, improved product quality and faster time-to-market.
• Better visualization of the final product, sub-assemblies and constituent
parts in a CAD system speeds the design process.
• CAD software offers greater accuracy, so errors are reduced.
• A CAD system provides easier, more robust documentation of the design,
including geometries and dimensions, bills of materials, etc.
• CAD software offers easy re-use of design data and best practices.
CAD
• Greater flexibility.
• Reduced lead times.
• Reduced inventories.
• Increased Productivity.
• Improved customer service.
• Improved quality.
• Improved communications with
suppliers.
CAM
• Better product design.
• Greater manufacturing control.
• Supported integration.
• Reduced costs.
• Increased utilization.
• Reduction of machine tools.
• Less floor space.

Benefits of CAM
The benefits of CAM include a properly defined manufacturing plan that
delivers expected results in production.
• CAM systems can maximize utilization of a full range of production
equipment, including high speed, 5-axis, multi-function and turning
machines, electrical discharge machining (EDM) and CMM inspection
equipment.
• CAM systems can aid in creating, verifying, and optimizing NC programs
for optimum machining productivity, as well as automate the creation of
shop documentation.
• Advanced CAM systems with product lifecycle management (PLM)
integration can provide manufacturing planning and production personnel
with data and process management to ensure use of correct data and
standard resources.
• CAM and PLM systems can be integrated with DNC systems for delivery
and management of files to CNC machines on the shop floor.

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.

CONCURRENT ENGINEERING
“The simultaneous performance of product design and process design.
Typically, concurrent engineering involves the formation of cross-functional
teams. This allows engineers and managers of different disciplines to work
together simultaneously in developing product and process design.”
“Concurrent engineering methodologies permit the separate tasks of
the product development process to be carried out simultaneously rather than
sequentially. Product design, testing, manufacturing and process planning
through logistics, for example, are done side-by-side and interactively.
Potential problems in fabrication, assembly, support and quality are identified
and resolved early in the design process.”
Basic Goals of Concurrent Engineering (CE) are:-
• Dramatic improvements in time to market and costs
• Improvements to product quality and performance
• Do more with less

Benefits of Concurrent Engineering
• Reduces time from design concept by 25% or more.
• Reduces Capital investment by 20% or more.
• Continuous improvement of product quality.
• Increases Product Life Cycle Profitability.
• 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.
• Use of special methods like DFMA and FMEA.
• Different departments can start their work simultaneously.
• Improve workflow.
• Eliminates conflict and procedures.
• 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.

Fig: Concurrent engineering (Simultaneous or parallel) vs Sequential engineering
Fig: No. of Changes for Concurrent & Traditional Engineering

WINDOW & VIEWPORT
A window defines a rectangular area in world coordinates. You define a
window with a GWINDOW statement. You can define the window to be
larger than, the same size as, or smaller than the actual range of data values,
depending on whether you want to show all of the data or only part of the
data.
A viewport defines in normalized coordinates a rectangular area on
the display device where the image of the data appears. You define a viewport
with the GPORT command. You can have your graph take up the entire
display device or show it in only a portion, say the upper right part.
WINDOW DEFINITION
The window must be defined the feet or meters or miles on in any length
dimension horizontally and vertically. It is more common to define the corners
of the window with reference to some world cordinate origin. These
dimensions will be input into the computer as (x,y) data, and subsequent
manipulations will be supplied to this computer model.
In the general case, with reference to origin O in fig, let as assume
that the window QRST is defined by the following limits in the world

Coordinates:
𝑊l = 𝑥 − coordinate of left edge of window, TQ
𝑊r = 𝑥 − coordinate of right edge of window, RS
𝑊b = 𝑦 − coordinate of bottom edge of window, QR
𝑊t = 𝑦 −coordinate of top edge of window, ST
Fig: Parameters for (a) Window, (b) Viewport
The coordinates of the bottom left, bottom right, top right and top left corners
of the window, designed Q,R,S and T in fig are
Q(𝑊l, 𝑊𝑏), 𝑅 𝑊r, 𝑊b , 𝑆 𝑊r, 𝑊t , and 𝑇(𝑊l, 𝑊t)

One way of inputting the window parameters is
SET WINDOW(𝑊l, 𝑊b , 𝑊r , 𝑊t)
This sequence (𝑊l, 𝑊b , 𝑊r , 𝑊t) of the window limits is the more common one
VIEWPORT DEFINITION
This zone may be defined in screen coordinates (s,t) or in plotting (pixel)
coordinates (p,q). More commonly, it is defined in the Normalized
coordinates (u,v) already, ranging from (0,0) at left bottom to (1,1) at top
right.
The advantage of normalized coordinates is the viewing
transformation relationship derived on this basis can be applied to any screen
display aspect ratio (b/h) and any resolution (m by n pixels). Further, with
(u,v) known, we can get the (s,t) and (p,q) coordinates by use of equations.
Let us further assume that the viewport is defined by the following limits in
the normalized coordinates, with reference to origin O’.
Coordinates:
𝑉l = 𝑢 − coordinate of left edge of viewport, HE
𝑉r = 𝑢 − coordinate of right edge of viewport, EF

𝑉b = 𝑣 − coordinate of bottom edge ofviewport, FG
𝑉t = 𝑣 −coordinate of top edge of viewport, GH
This quantities too are often designated variously. The coordinates of bottom
left , bottom right, top right, and top left corner of the view designated E,F,G
and H in fig are
E(𝑉l, 𝑉𝑏), 𝐹 𝑉r, 𝑉b , 𝐺 𝑉r, 𝑉t , and 𝐻(𝑉l, 𝑉t)
One way inputting the viewport parameters is
SET VIEWPORT(𝑉l, 𝑉b , 𝑉r , 𝑉t)
Again order of input may differ and need to specified.

Clipping to the world-coordinates window is usually applied to the
objects before they are passed through the window-to-viewport
transformation. For a 2D object, the latter transformation is simply a
combination of translation and scaling, the latter not necessarily uniform.
(a) Window (b) Viewport
A window and a viewport are related by the linear transformation that maps
the window onto the viewport. A line segment in the window is mapped to a
line segment in the viewport such that the relative positions are preserved.

The window, in effect, defines the portion of the graph that is to be displayed
in world coordinates, and the viewport specifies the area on the device on
which the image is to appear.
In above figure are showing follows:
• World coordinates -- Problem-oriented
• Screen coordinates -- Of device in use.
• Normalized screen coordinates -- (0,0) and (1,1) at opposite corners of the
screen.
• Window -- Visible rectangular region of the world. Boundaries are
specified in world coordinates.
• Viewport - A region, within the screen, that displays a window. Boundaries
are specified in
a. Screen coordinates
b. Normalized screen coordinates (transformations between window
and viewport coordinates are machine-independent)
• A window acts as a clip region only for future insertions.
• A window may have many viewports

Relation b/w Windows, and Viewports
1. A window defines a rectangular area
in world coordinates.
2. A window can be defined with a
GWINDOW statement.
3. The window can be defined to be
larger than, the same size as or
smaller than the actual range of data
values, depending on whether we
want to show all of the data or only
part of the data.
4. A window is related by the linear
transformation that maps the
window into the viewport.
5. A line segment in the window is
mapped to a line segment in the
viewport such that the relative
positions are preserved.
1. A viewport defines in normalized
coordinates a rectangular area on the
display device where the image of
the data appears.
2. A viewport is defined with the
GPORT command.
3. We can have our graph take up the
entire display device or show it in
only a portion, say the upper right
part.
4. A view port is also related by the
linear transformation that maps the
window into the viewport
5. The ultimate intention of computer
graphics is to represent the image of
any object in the window.

MODELING COORDINATES
We can construct the shape of individual objects in a scene within separate
coordinate reference frames called modeling (local) coordinates.
WORLD COORDINATES
Once individual object shapes have been specified, we can place the objects
into appropriate positions within the scene using reference frame called world
coordinate.
To be useful, a graphics system needs to be universal in scale: it
needs to be able to represent atoms or galaxies on the same screen and do both
with minimal hassle for the user. This dictates the requirement that the
package should accept arbitrary rectangular coordinates supplied by the user.
The users coordinates, denoted (x,y), will be called World Coordinates
throughout the course. In the user's world, he chooses an origin O, a pair of X
and Y axes centered at O, and a unit of length along these axes, and all
positions are then specified relative to the origin and measured in his length
units along the axes. The length unit could be feet, angstroms or light years.
Note that the World is infinite in extent - there is no largest or smallest
coordinate. This corresponds to our need for example to possibly track

Fig: Modeling, World. Device & Normalized Coordinates
a space-ship throughout the galaxy, or to represent a black hole collapsing to a
point. Furthermore the coordinates are also continuous
NORMALIZED DEVICE COORDINATES
Finally, the world coordinates description of the scene is transferred to one or
more output-device reference frames for display, called device (screen)
coordinates.
A graphic system first converts world coordinate positions to
normalized device coordinates, in the range 0 to 1.This makes the system
independent of the output-devices.

HOMOGENEOUS COORDINATES
Homogeneous coordinates.(x,y,w) instead of (x, y)
Points (x, y) in the plane z = w of a 3D space.
Fig: Homogeneous Coordinates

NORMALIZED HOMOGENEOUS COORDINATES
Normalized device coordinates (NDCs) make up a coordinate system that
describes positions on a virtual plotting device. The lower left corner
corresponds to (0,0), and the upper right corner corresponds to (1,1).
NDCs can be used when you want to position text, lines, markers, or polygons
anywhere on the plotting device (that may or may not already contain a plot).
Fig: Normalized Homogeneous Coordinates

Introduction of cad cam

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