20-11-2012, 05:38 PM
Introduction to CAD/CAM
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Throughout the history of our industrial society, many inventions have been patented and
whole new technologies have evolved. Perhaps the single development that has impacted
manufacturing more quickly and significantly than any previous technology is the digital computer.
Computers are being used increasingly for both design and detailing of engineering components
in the drawing office.
Computer-aided design(CAD) is defined as the application of computers and graphics
software to aid or enhance the product design from conceptualization to documentation. CAD
is most commonly associated with the use of an interactive computer graphics system, referred to
as a CAD system. Computer-aided design systems are powerful tools and in the mechanical
design and geometric modeling of products and components.
Rationale for CAD/CAM
The rationale for CAD/CAM is similar to that used to justify any technology-based
improvement in manufacturing. It grows our of a need to continually improve productivity,
quality and competitiveness. There are also other reasons why a company might
make a conversion from manual processes to CAD/CAM:
· Increased productivity
· Better quality
· Better communication
· Common database with manufacturing
· Reduced prototype construction casts
· Faster response to customers
CAD/CAM Hardware
The hardware part of a CAD/CAM system consists of the following components
⑴ one or mare design workstations, ⑵ digital computer, ⑶ plotters and other
output devices, and⑷ storage devices. The relationship among the component is
illustrated in Fig.10.1. In addition, the CAD/CAM system would have a
communicatio interface to permit transmission of data to and from other
computer systems, thus enabling some of the benefits of computer integration.
The workstation is the interface between computer and user in the CAD system.The design
of the CAD workstation and its available features have an important influence on the convenience,
productivity, and quality of the user´s output. The workstation must include a
digital computer with a high-speed control processing unit(CPU). It contains
require a and logic/arithmetic section for the system. The most widely used
secondary storage medium in CAD/CAM is the hard disk, floppy diskette, or a
combination of both.
The typical I/O devices used in a CAD system are shown in Fig.10.2. Input
devices are generally used to transfer information from a human or storage
medium to a computer where ¨CAD functions¨ are carried out. There are two
basic approaches to input an existing drawing:model the object on a drawing or
digitize the drawing. The standard output device for CAD/CAM is a CRT display.
There are two major of CRT displays: random-scan-line-drawing displays and
raster-scan displays. In addition to CRT, there are also plasma panel displays
and liquid-crystal displays.
CAD/CAM Software
Software allows the human user to turn a hardware configuration into a powerful design and
manufacturing system. CAD/CAM software falls into two broad categories,2-D and 3-D,
based on the number of dimensions are called 2-D representations of 3-D objects
is inherently confusing. Equally problem has been the inability of
manufacturing personnel to properly read and interpret complicated 2-D
representations of objects. 3-D software permits the parts to be viewed with
the 3-D planes-height,width, and depth-visible. The trend in CAD/CAM is toward
3-D representation of graphic images. Such representation approximate the
actual shape and appearance of the object to be produced; therefore, they are
easier to read and understand.