Chapter 1 Introduction

AbstractCAD/CAM technology have been impacting the design drafting and manufacturing of product significantly. CAD/CAM deparments are now vissible in many engineering industries like automobiles, machine tools etc. All mass production industries are also leading towards computer integrated manufacturing which uses flexible automation involving robot technology. CAD/CAM and automation tools have now been devloped fully and the technology now being used.

A slash between CAD/CAM/CAE indicates many shared functions of design and manufacturing.

CAD/CAM are highly eveolving areas of computer application and has revolutionised engineering industry. This revolution begines with simple drafting system, which allowed computer aided drafting and progressed to high level of computer aided designing which includes engineering analysis by the way of modelling and finite ellement analysis. This tools collectively known as CAD system. On simmilar lines manufacturing system begine with hardwire, NC controllers using tapes as input devices. This ystems have now been rendered obsolete with the advent of softwire CNC and DNC controls. Modern concepts of automation like FMS and the use of robot technology has change the look of shop floor.

To become more competatives in world with divercity of products, with countinous changes, the companies must moderise and increase flexibility of production systems.

The companies find out that the interactive design of a product is a most efficiency tool for analysis end evaluation. So the use of internet data base and CAD/CAM/CAE software creates visual data base and industrial geometry design. Process and product development using Computer and internet envornment allow a substantially costs and time economy.

On the market there is a lot of CAD-CAM-CAE software which offer specific tools for engineering design into a tri dimensional virtual space.

CAD/CAM/CAEIntroduction to CAD/CAM :CAD : stands for Computer Aided Design. It refers to the design and technical drawing of various engineering applications on computers. A related term, CADD, stands for Computer Aided Drafting and Design.CAD implementations have evolved dramatically over the last few decades. CAD was initially limited to produce drawings similar to hand drafted drawings at the beginning of its development history. Todays advances in CAD technology have allowed more skillful and complex applications in engineering.

The useful features of CAD include the ability to make changes in the design easily, and validate designs against design rules. CAD models can also be used to simulate designs without building a physical prototype.CAM : An engineering industry based on the needs of the people transforms ideas in to products, which can then be sold, so that the product can serve its purpose.The various phases of these operations have drastically changed with the advent of CAD/CAM technology. The ideas and plannning can be crystallised by using the various tools available with CAD technology. CAD allows the designer to model, analyse, review and optimise his designs. Besides these, it also generates the data and drawings which can be used for manufacturing.

Just as in the design phase, the methods of manufacturing have also undergo a tremendous change with the use of Numerically Controlled(NC) and Computer Numerically Controlled (CNC) machine tools.NC technology is based on controlling the motion of the drives of the machine tool as well as the motion of the cutting tool via programming code. The above tools allow integration of varioos phases of the product cycle. The use of computer system to plan, manage and control the operations of manufacturing plants is reffered to as CAM.Development History of CAD/CAM Technology :The first commercial numerical-control programming system was developed in 1957 by Dr. Patrick J. Hanratty. The first CAD system was developed during the 1960s. Several companies, such as MCS, were founded in the 1970s and they began to offer automated design/drafting systems in the early 1970s. CAD/CAM SYSTEMS FOR PART PROGRAMMING :

CAD systems are used to build the geometry of the parts.Once the component has been geometrically defined,the CAM softwares allows the user to pick tools,select machine speed,and other parameters.The software then allows the user to specify the direction of the cut.Once this is done,the CAM software can directly generates the toolpath data as per the instructions.

Higher level systems used use Solid models for tool path generations.In this case,the tool paths are automatically linked with the part data base.Thus,if there is geometrical change,the tool path data would also be automatically updated.These systems are highly suitable for industries involving producing complex components.Basic CAD/CAM HardwareWorkstation and PC

A workstation is a general purpose computer designed to be used by one person at a time and it offers higher performance than normally found in a personal computer, especially with respect to graphics, processing power and the ability to carry out several tasks at the same time. A personal computer is an inexpensive microcomputer, originally designed to be used by only one person at a time, and is compatible with IBM PC (though it may sometimes refer to non-IBM compatible machines).

Input DeviceA keyboard and mouse are designed to enter data by manual depression on keys. Most keyboards have characters printed on the keys, they usually represent characters selected from some language alphabet, along with numbers and punctuation. Output Device Computer monitors show still or moving images generated by a computer. It is driven by a graphics card and generally matches one or more display standards.

Plotters are used primarily in drafting and CAD applications, where they have the advantage of working on very large sized paper while maintaining high resolution.CAD/CAM SoftwareSoftware is created with programming languages and related utilities. CAD/CAM systems usually include a variety of software. In an open system, the software may come from a wide range of sources, including those purchased from a third party or developed from users.

The latest types of CAD/CAM software are those with built-in intelligence, some of them are the following.

Parametric design software: These packages represent geometry by parameters, which linked together by direct values or mathematical equations. Feature based software: A feather based software uses predefined geometry or behaviour (e.g. a rounding operation) called feathers to generate CAD/CAM models. Knowledge (expert) based software: Systems contain a knowledge base of specialized information that the expert uses to do his or her job. This generally consists of data drawn from textbooks, technical papers plus information such as rules of thumb, wise guessing criteria.

Basic Concepts (1) Database

A database is an information set organized for flexible searching and utilization. (2) Data structureA data structure is a specialized format for organizing and storing data. Often a carefully chosen data structure will allow a more efficient algorithm to be used.

(3) Algorithm

Algorithm is a computable set of steps to achieve a desired result. A computer pro-gram can be viewed as a complex algorithm.

(4) Raster

A scanning pattern of parallel lines that forms the display of an image projected on a display screen.(5) Raster graphicsA raster graphics image, or bitmap, is a data file or structure that consists of a generally rectangular array of pixels on a computer monitor or other display device. (6) Vector graphicsVector graphics describe the use of geometrical primitives such as points, lines, curves and polygons to represent images in computer graphics.(7) Database managementA database management system (DBMS) is a computer program designed to manage a database, a large set of structured data, and run operations on the data requested by numerous users.(8) NetworksAs the increasing dependence on communication and data exchange in engineering and manufacturing, system hardware is increasingly being tied together into networks. Networks allow systems to share data and software. The most common network is LAN (Local Area Network). Large geographic areas are handled by WAN (Wide Area Network).APPLICATIONS AND PHASES IN CAM/CAM :Typically the applications of CAM/CAM can be divided in to two broad categories the operation of the plant.

1.MANUFACTURING CONTROL :

This process can be further divided into two parts .This fruther part is called as computer process monitoring.In this case,the computer ditectly interfaces with the process and recieves the data about the process.In short the computer doesnot control the process,but just monitors it.A typical example of this process is the use of digitalread-outs.While manufacturing on lathes,the digital read-outs give the numericals value of the coordinates. These are used by the operator to achieve necessary tolerances.

The second area of manufacturing control is called as computer process control.In this case,the computer not only monitores the data that it recieves,but also sends signal to control manufacturing process.Human intervention is only incidental and may occure only under extraordinary circumtances.This method of control is highly effective and efficient.As an example,consider a manufacturing process which requires highly controlled temperatures,where the computer continuously monitors the temperatures and takes corrective action to maintain this tempteratures. 2. MANUFACTURING PLANNING :

In this case the computer plays a support role for manufacturing.There are no direct interfaces between the two.The computer is considered off line and it is used to provide plans,schedules,forecasts,stastistics,instructions and informations to effectively plan and indirectly controlled production.Typically,operations such as NC part programming,computer aided process planning,material resource planning,production scheduling,cost istimation,production and inventory planning are some of the key area of this phase of CAM.

ADVANTAGES OF CAD/CAM

1. High productivity and reduced lead times.

2. Accuracy in design.

3. Better controlled over the complete project process

4. Modifications in design are easy.

6. Better communications and presentation of design.

7. Optimised solution as a result of detailed engineering analysis.

8. Automatic database creations assists in creations of manufacturing documentations.

Introduction to CAE : A few years ago, when a Hong Kong manufacturer decided to invest in CAD/CAM technology, he was not sure whether the investment could be justified, in terms of possible savings achievable in the product design stage and during the manufacturing operations. The manufacturer was actually buying a Vision, something which he might claim as Strategic Advantages against his competitions. Computer Aided Engineering (CAE) technology offers "Mathematical Analysis on Computerized Models, simulating real-life Physical structural analysis as well as thermal analysis and plastic flow analysis.

Fundamentals of Computer Aided Engineering provides support for all students involved in computer aided engineering courses in civil, mechanical, chemical and environmental engineering. This book is also a useful reference for researchers, practising engineers using CAE and educators who wish to increase their knowledge of fundamental concepts.Computer - aided engineering

Any use of computer software to solve engineering problems. With the improvement of graphics displays, engineering workstations, and graphics standards, computer-aided engineering (CAE) has come to mean the computer solution of engineering problems with the assistance of interactive computer graphics. See COMPUTER GRAPHICS. CAE software is used on various types of computers, such as mainframes and superminis, grid-based computers, engineering workstations, and even personal computers. The choice of a computer system is frequently dictated by the computing power required for the CAE application or the desired level and speed of graphics interaction. The trend is toward more use of engineering workstations.

Design engineers use a variety of CAE tools, including large, general-purpose commercial programs and many specialized programs written in-house or

elsewhere in the industry. Solution of a single engineering problem frequently requires the application of several CAE tools program is made up of a number of mathematical models encoded by algorithms written in a programming language. The natural phenomena being analyzed are represented by an engineering model. The physical configuration is described by a geometric model. The results, together with the geometry, are made visible via a user interface on the display device and a rendering model CAE allows for many more iterations of the analysis-design cycle thanwas possible by hand computation, especially when the CAE is coupled with

optimization systems that drive this cycle automatically. The benefits are translated into improved productivity and quality of design.

Solid modeling on a mainframe via a CAE workstation :

Though many small CAE applications programs are written for personal computers, of which most engineering companies have a wide array, most large, commercial CAE programs do not perform effectively or at all on personal computers. Engineering workstations, on the other hand, have the necessary computer power and local resources, and usually run only one CAE program at a time and serve only one user. As a result of this independence, a demanding CAE code at one workstation node in a computer network will not affect the response time for other users.

Finite-element stress analysis using commercial CAE software :A wide variety of output devices are available for CAE images. The most popular are ink-jet and laser printers for color images and line drawings on paper and Mylar. Others include wall projection and stereovision display systems, often combined with positional and orientation input from the observer. Many types of graphics input devices are available forworkstations and mainframe displays. Cursor and tablet, mouse, joystick, ball, glove, function key box, and dial box are the most widely used. Light pens are generally in use on older-technology displays. Applications :The fields of civil, architectural, and construction engineering have CAE interests similar to mechanical CAE with emphasis on structures. Aerospace, mechanical, industrial, and manufacturing engineering all make use of mechanical CAE software together with specialized software.Conclusion :The improvement in computer engineering and scanning technology offers

much faster and less costly solutions for product design and product modifications.

It offers powerful tools for Hong Kong OEM manufacturers. who are in many

cases, having to work from manual prototypes or just a sample of the end

product, without any drawings or specifications.References :

CAD/CAM and Automation by Farazdak Haideri.

CAD/ CAM Principles and Applications by P. N. Rao.

CAD/CAM/CAE by Radhakrishana P. and Subramanyam.

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