ENGINEERING: REPORT CAM AND CAD

INTRODUCTION

From this inception, it has been human nature to innovate, discover, invent new things and so has been his creation. Design may be pronounced as the synonym for creation. So there is no end to man’s creation, design and hence CAD. By passage of time it’ll be even smarter, quicker and sophisticated. COMPUTER-AIDED DESIGN (CAD) AND COMPUTER-AIDED MANUFACTURING (CAM).

The Origins of CAD/CAM:

CAD had its origins in three separate sources, which also serve to highlight the basic operations that CAD systems provide.

The first source of CAD resulted from attempts to automate the drafting process. These developments were pioneered by the General Motors Research Laboratories in the early 1960s. One of the important time-saving advantages of computer modeling over traditional drafting methods is that the former can be quickly corrected or manipulated by changing a model's parameters.

The second source of CAD was in the testing of designs by simulation. The use of computer modeling to test products was pioneered by high-tech industries like aerospace and semiconductors.

The third source of CAD development resulted from efforts to facilitate the flow from the design process to the manufacturing process using numerical control (NC) technologies, which enjoyed widespread use in many applications by the mid-1960s. It was this source that resulted in the linkage between CAD and CAM. One of the most important trends in CAD/CAM technologies is the ever-tighter integration between the design and manufacturing stages of CAD/CAM-based production processes.

The development of CAD and CAM and particularly the linkage between the two, overcame traditional NC shortcomings, in expense, ease of use, and speed by enabling the design and manufacture of a part to be undertaken using the same system of encoding geometrical data. This innovation greatly shortened the period between design and manufacture and greatly expanded the scope of production processes for which automated machinery could be economically used. Just as important, CAD/CAM gave the designer much more direct control over the production process, creating the possibility of completely integrated design and manufacturing processes.

The rapid growth in the use of CAD/CAM technologies after the early 1970s was made possible by the development of mass-produced silicon chips and the microprocessor, resulting in more readily affordable computers. As the price of computers continued to decline and their processing power improved, the use of CAD/CAM broadened from large firms using large-scale mass production techniques to firms of all sizes. The scope of operations to which CAD/CAM was applied broadened as well. In addition to parts-shaping by traditional machine tool processes such as stamping, drilling, milling, and grinding, CAD/CAM has come to be used by firms involved in producing consumer electronics, electronic components, molded plastics, and a host of other products. Computers are also used to control a number of manufacturing processes (such as chemical processing) that are not strictly defined as CAM because the control data are not based on geometrical parameters.

Markets and Applications:

The market for CAD hardware and software has experienced substantial growth since the early 1970's. The Office of Technology Assessment (OTA) of the U.S. Congress states, "Between 1973 and 1981, the CAD system market grew from under $25 million in annual sales to over $1 billion," a fortyfold increase. The years ahead may be even more promising. The Yankee Group, a Boston-based market analysis firm, predicts that sales may reach $6.9 billion annually by 1987, with an average annual growth rate of over 40 percent.

At present, the principal mechanical for CAD are within the mechanical manufacturing industry. Aerospace and automotive companies are the heaviest users, but other segments of the industry, such as machine tool manufacturers, are incorporating CAD into their operations.

Within these enterprises, CAD is only one member of a family of Computer based technologies that is altering the nature of American manufacturing. Computer-aided manufacturing (CAM) is usually mentioned in the same breath as computer-aided design. This juxtaposition, CAD/CAM, refers to the capability of systems to design a part or product, devise the essential production steps, and transmit this information electronically to manufacturing equipment, such as robots. These design and manufacturing tools may, in turn, be linked to management information systems (MIS), which enable managers to monitor closely all aspects of a company's operations.

While mechanical applications of CAD account for nearly one-half of the systems sold today, other industries recognize the benefits it affords. For the electronics industry, CAD offers considerable advantages, particularly in the design on printed circuit boards and integrated circuits. The design of these components can be tedious and time consuming. And so many lines and cross lines must be drawn that errors are not easily detected. CAD not only speeds up the drawing but detects errors as well.

Architecture, engineering, and construction applications offer the greatest potential for growth in sales, according to a recent industry survey. Although the construction and electronics industries each represent about 16 percent of the CAD market now, the penetration is far less extensive. However, both simple drafting applications and more complex design and analysis are evident within the industry. Architectural drafters will be able to complete drawings of a higher quality in much less time. Architects and engineers will be able to submit their designs to more exhaustive structural and stress analyses. Piping and electrical layouts will be made easier and the design and allocation of interior space will be facilitated as well. As a management tool, the data base created during the project will provide an effective means of inventory control enabling contractors not only to speed construction but to reduce costs.

CAD is also having an impact upon cartography. Geographers use CAD systems to help them draft maps used for environmental impact analysis and land use planning and for charting landfill contours for strip mining. Some software packages are available that aid in extraterrestrial mapping.

Process industries, such as oil and gas refineries and chemical manufacturers, as well as power and utility companies, must plan, construct, operate, and maintain electrical grid and pipeline networks. CAD makes these complex tasks easier. CAD even has applications in landscape design, interior design, and fashion design. Some high fashion couturiers use CAD systems to lay out patterns on expensive fabrics as a way to minimize waste.

Using CAD, it is possible to simulate in three dimensions the movement of a part through a production process. This process can simulate feed rates, angles and speeds of machine tools, the position of part-holding clamps, as well as range and other constraints limiting the operations of a machine. The continuing development of the simulation of various manufacturing processes is one of the key means by which CAD and CAM systems are becoming increasingly integrated. CAD/CAM systems also facilitate communication among those involved in design, manufacturing, and other processes. This is of particular importance when one firm contracts another to either design or produce a component.

CAD/ CAM (Definition): The process of creating, optimizing, analyzing and manufacturing a product completely by the aid of computer is called CAD/CAM.

Stages involved in complete CAD/CAM:

Ø Drafting and Documentation

Ø 3D Modeling and Designing

Ø Design simulation and Analysis

Ø Manufacturing using CNC or DNC programming.

Future Trends in CAD/CAM:

The rest of this decade will see continued advances in techniques for creating and manipulating workpiece geometry. Standards for user interfaces, data transfer, and computer architecture will give users new flexibility. All of these developments promise to have a significant impact on numerical control and other manufacturing applications.

Where are numerical control (NC) and computer-aided design/computer- aided manufacturing (CAD/CAM) headed? What current trends are influencing the direction these key manufacturing technologies are taking? The answers to these important questions should help us anticipate and plan for the future.

For years, manufacturing companies in the United States have been criticized for a lack of long-range planning. Intense pressures to meet short- term goals are usually blamed for this situation. But another factor has also been at work. Long-range planning means accepting a certain degree of uncertainty. Technology changes so rapidly that it is very difficult to predict what techniques, processes, or systems will predominate or become obsolete.

But decisions about technology are not like dropping an anchor. They are like spreading a sail. Leaders of a manufacturing enterprise must set a course toward a destination, then be ready to shift with the winds.

The following pages are meant to be a breezy review of the major currents blowing us toward the future. They represent the forces that will both guide and propel the decision-making process.

Capture and Share Knowledge:

The collective knowledge of individuals within a company is a clear corporate asset. In the 90s, CAD/CAM systems will provide the tools to electronically capture this knowledge and apply it to the design and manufacture of components. Current CAD/CAM technology is related primarily to the dimensional characteristics of a component. However, other properties, such as material, cost, manufacturability, inspectability, assembly fit, tolerances, and so on, are equally important. Design standards, rules, and constraints also impact the design.

Today, manufacturing know-how is mainly locked in the minds of a few individuals at each company. CAD/CAM systems will be extended to capture and utilize this knowledge. This will be accomplished by direct coupling with dedicated knowledge-based engineering systems or by adding that capability to the base CAD/CAM functionality. Knowledge-based engineering will become an integral component of a CAD/CAM system.

New software tools will help these experts record the information and thought processes with which they make decisions. Once captured, these records become readily available to those making the actual design decisions on future projects. These tools will have a major impact on automation of the design and manufacturing process.

Simultaneous Engineering:

Sharing information is another urgent issue where new techniques and methodologies will have an impact. One of the most important of these is simultaneous engineering. Simultaneous engineering (or concurrent engineering) can be defined as a methodology in which the design of the product is accomplished simultaneously with the design of the process to produce the product. In this methodology, design engineering works together with manufacturing engineering and other related functions during the design phase to incorporate downstream manufacturing considerations into the product design.

Companies that have implemented simultaneous engineering have typically experienced fewer design changes, shorter lead times, lower manufacturing costs and improved quality. This concept not only applies within a company, but can be extended to the supplier network. As a company better understands the issues being faced by the supplier, and the supplier offers design suggestions based upon manufacturing knowledge, a more effective process results. The inclusion of suppliers and customers into the manufacturing process creates a "virtual factory." Different companies will work so closely together as a team that it will be as if they were actually a dedicated organization under one roof.

Product Data Management:

Many organizations using CAD/CAM now have thousands of files representing drawings, engineering analysis results, and other information related to product definition. Managing these collections has become a problem. Product Data Management (PDM) software is emerging as a solution.

A PDM system collects, organizes, files, accesses, and controls any type of data about a company's products. Typical information managed by a PDM system includes specifications, drawings, geometric models, models produced by finite element analysis, process plans, NC programs, and so on. Although product definition data could be in hard copy form, it is generally in digital files.

PDM software is provided by CAD/CAM vendors and independent suppliers. Good capability is now available in homogeneous environments and, in the 1990s, management of files in distributed, heterogeneous environments will be commonplace. PDM systems will soon become more closely integrated with both CAD/CAM and standard management information systems.

A related technology is image management systems. In image management systems, paper documents, such as drawings, are scanned into electronic form. The documents can then be indexed, manipulated, accessed within a network, and managed as in a PDM system.

Maturity:

The CAD/CAM industry has become a multibillion dollar industry. In the 1990s, it will become relatively mature. Industry growth rates, although substantial by most standards, will ease. Acquisitions, mergers, and alliances will accelerate. The trends noted, for the most part, are evolutionary and not revolutionary. Yet CAD/CAM in general, and automated manufacturing in

particular, will remain an exciting field.

New technologies will continue to emerge, and for the most part, will be introduced by niche companies. User organizations will become more sophisticated and hence, more inclined to implement the best product for the task at hand. World class manufacturing demands the appropriate utilization of advanced technology. It is essential for those firms striving to remain competitive in a worldwide marketplace.

COMPUTER AIDED DESIGN (CAD):

Computer-aided design (CAD) involves creating computer models defined by geometrical parameters. These models typically appear on a computer monitor as a three-dimensional representation of a part or a system of parts, which can be readily altered by changing relevant parameters. CAD systems enable designers to view objects under a wide variety of representations and to test these objects by simulating real-world conditions.

CAD for Beginners:

A completely new drawing can be created with a base drawing and slight modification of some part of it and unlike in paper drawings where a draughts man has to redraw again the whole drawing which, consumes not only his time but also reduces productivity and interest in work.

Once converted to CAD format, the drawings can be copied any number of times, any part can be added/removed to a drawing without disturbing the original one. Various engineering data can be retrieved as well from the drawings without doing any further calculations manually. An area where CAD has gained significant importance is Computer Aided Technologies. The advancements in this field have included a reduction in product development costs and shorter time spent on the design cycle.

Features:

Enhanced Geometry Creation:

The 1990s will see substantial enhancements in geometry creation, including solid modeling, feature-based geometry, associativity, inference systems, parametric design, and variational geometry functionality. Moreover, system architectures of the 1990s are likely to have a separate geometry subsystem that will serve all applications.

Geometry subsystems are now being independently developed and marketed in the same manner as database management, graphics, and data communication systems. They will provide a geometry toolkit to be utilized by all applications.

Advanced geometry software systems will provide an architecture in which wireframe, surface, and solid representations can be intermixed within the same model. Such a system will support applications that involve time, the fourth dimension. For example, this capability will permit direct computation of potential collisions between two solid objects moving through space, as in robotic or machining applications. Solid models provide a complete and unambiguous representation of a real object. They permit a more direct and accurate computation of mass properties. Internal characteristics of the object can also be included in the model.

Solid product models will form the core for a single product definition in a CAD environment. All functions will reference this model. NC machining systems, now under development in some firms, will be introduced to machine directly off a solid model.

Feature-based or form-feature-based modeling is a higher level of design. It recognizes that designers and engineers generally think in terms of blind holes, through-holes, slots, shafts, chamfers, ribs, rounds, fillets, and so on, rather than lines, circles, arcs, or Boolean manipulation of solid objects such as boxes, cylinders, or cones. Furthermore, the direct creation of a feature, as opposed to a buildup of the feature, improves the productivity of designers.

A related capability is Associativity. In associative systems, relationships are established between models and dimensions in such a way that changes in the model or its dimensions result in an automatic update of other related models or dimensions. Further, a change to a part within an assembly can trigger a corresponding change to that part in other assemblies.

In an inference system, the CAD system infers the next step by the operator. It automatically generates the next line, arc, circle, and so on. This is usually done by placement of the mouse pointer or other input device. By so doing, design productivity is increased. If the system inference is incorrect, it can be undone and re-entered.

Parametric design systems were introduced in the 1980s. In these systems, parameters are established as opposed to actual dimensions. Relationships can also be established among the parameters. For example, one side of an object is always twice that of another side of an object. When combined with an associativity capability, a powerful system results. A change in one dimension can also change other dimensions and update the geometric model.

A similar but somewhat more powerful capability is that of variational geometry. A variational design system completely defines the problem with a series of simultaneous equations. Thus, it offers greater flexibility by removing restrictions on interdependencies and solves all the values at once. If engineers change any type of condition or vary any design parameter, the variational design system can still adjust all other design parameters to arrive at a new solution that accounts for interactions among all the conditions defined.

A word about rapid prototyping is appropriate here. Prior to full-scale production, most manufacturers produce multiple prototypes in order to see and touch a part directly, to hold and examine the thing without recourse to abstract geometry. This step can involve significant time and cost.

Technology has been and is continuing to be introduced that reduces this time and cost substantially. The original technology is termed stereolithography but other approaches such as fused deposition modeling (Figure 3) have also appeared. In all cases, systems utilize the geometry from a CAD model as the starting point. Typically, the model is then mathematically sliced to obtain the geometry at a given elevation. Material is then deposited, layer by layer, to build the physical model.

Changes in User Interfaces:

Significant changes will take place in user interfaces to a graphics-based computing system. These changes will make the computer more like an extension of the user's mind. The impact of a new user interface was made strikingly clear with the introduction of the Macintosh family of personal computers by Apple Computer Corp. A totally new look and feel for the user was created by the mouse input, windows, pop-up menus, icons, and so on that were introduced with the Mac.

Proprietary graphical user interfaces (GUI) are giving way to pseudo standard solutions for UNIX-based systems. At the lowest level, the X windowing system serves as the clear standard. At the next higher level, where the look and feel is created, the Open Software Foundation's Motif and the UNIX International's Open Look are the two primary competitors for a de facto GUI standard. Stand-alone GUIs based upon these standards are likely to become available and serve as common front-ends to CAD/CAM systems that incorporate a variety of different applications.

Other innovations on the near horizon include multimedia, voice input and virtual reality. In multimedia systems, documents or files will be created with audio, animation, and/or video, as well as the conventional data, text, and graphics. This combination is then simultaneously presented on the display. Multimedia input will allow the user to absorb greater quantities of information by using more than one sense to process information. A message could include voice comments, animation, text, and full-motion color video--even music.

Voice input is likely to become practical in this decade. The user can then enter commands to a CAD/CAM system by voice as opposed to keyboard, mouse, tablet, and other input forms.

In a virtual reality system, the user is placed within the environment of the computer visualization. An architect can walk around inside a virtual building that is being designed. An NC programmer can "walk" along a tool path. A doctor can explore a patient's heart before surgery. In virtual reality, one can directly manipulate the simulation by grasping, moving, and changing elements of the simulation with a gloved hand. This may be the ultimate intuitive user interface.

Contoured Surfaces:

A pair of plastic speaker grilles for portable radios demonstrates the strategic value of Beach's integrated manufacturing capability. These grilles feature a curved surface that flows smoothly across the face of the radio and merges into its case. The clean, sweeping lines were an essential aesthetic element of this design.

Achieving the smooth surface contour and having it cleanly blend into the contour lines of the case were the prime challenges in designing and building the mold set. The finished grille, after shrinkage, had to have dimensional tolerances within a [+ or -]0.002-inch band around the entire curved periphery for easy assembly and an acceptable fit. Without CAD/CAM, these objectives could not be met (Figure 1).

Phil Kiesler, Chief Engineer, and Gary Wilson, CAD Manager, recall that the original drawing received in the request for a quote did not contain detailed dimensioning. Several points, radii, and matching curves were described and detailed, but smooth blending of surfaces was left to this mold shop.

The design work was done on a Calma CAD system by starting with the defined dimensional data and then using a series of splines and Bezier curves (curves drawn through points so no sharp junctures or cusps appear where they meet). One spline line must flow smoothly into the next. It turned out that this was no small task, because the rate of curvature slightly changes across the face of the grilles. In addition, blending had to be smooth in all directions. To make matters worse, the original specification called for hundreds of holes in each grille that had to be normal to the surface of the workpiece. The pattern easily could be defined, but some sophisticated math routines were needed to orient each one normal to the grille surface. This orientation would also greatly increase the mold cost. After a discussion, the customer agreed that the holes could be parallel. Again, the computer assisted in working out the various patterns for study and comparison.

The design database was generated in about four days, but it was only the beginning. The design showed the final shape of the workpiece and gave a thorough description of it in coordinate axes dimensions. But two mold halves also were needed, with the appropriate cavity, mounting surfaces, ejector pins, coolant connections, plastic flow channels, and all the other features inherent in the complete mold set.

One of the principal considerations in plastic mold design is allowing for shrinkage. Although some mathematical routines can be worked out, they are not infallible. There is no substitute for experience in this area. Plastic shrinkage during cooling is not the only problem. A decision had to be made about machining the critical cavity areas. Mr. Wilson and Mr. Kiesler chose to machine all mold elements except for finishing the cavity, then use ram EDM to finish. The cavity, in 420 stainless steel, was roughed out to within 1/16 inch of its finish dimension, and then hardened. It was then turned over to the ram EDM unit for the final finish cut. Individual NC part programs had to be generated to rough the mold cavity, machine the EDM electrode, and even machine a prototype part for visual inspection and checking. Working from the basic design resident in the CAD computer, Mr. Wilson entered the desired machining sequence (the logical sequence of machining operations), the tooling that was to be used, and the offsets and shrinkage factors that were critically important. For example, EDM requires an offset to allow for the dielectric fluid and spark gap. It must be stated in the proper direction for either the male or female half of the mold. When using a ball nose milling cutter to rough out a cavity, the cusp height allowances must be stated to leave enough material for the finish cuts.

Applications of CAD:

Computer Aided Design (CAD) is a type of computer-based tool used for drafting and designing. CAD is useful in various designing fields such as architecture, mechanical and electrical fields being some of them. This is a type of software, which enables users to create rapid and precise drawings and rough sketch plans of main products. It provides a flexible pattern in the drawing process that users can alter as according to their required dimensions with minimal efforts.

CAD is not only made for artists specifically but has the diversity to entertain all kinds of designing enthusiasts. This software has all built in features as per users need and come with many templates and symbols, for designing and drafting purposes, which gives it a wide area of application. It is the primary geometry-authoring tool used for all 2D and 3D designing purposes.

It is useful for engineers, architects, and other designing professions.

CAD is applied in mechanical, automotive, aerospace, consumer goods, machinery, and shipbuilding applications. In this field, it is used for designing various machinery and tools that are useful for manufacturing purposes. In the field of electronics, it is used in manufacturing process planning, digital circuit design, and other software applications. In the field of architecture, it is used as an effective tool for designing all types of buildings and assessing the integrity of steel-framed buildings. It enables them to design buildings in 2D and 3D models to give almost a real replica of the original work. It is useful in engineering processes in conceptual

design, and laying out and analyzing components in manufacturing methods. Computer Aided Software Applications are now available on personal computers to facilitate users to work from home.

Many professionals use the CAD software because of its precise and creative benefits. Lower product development costs and reduced design cycles are some other attributes of the CAD software. Many educational institutions are nowadays indulging in teaching CAD to their students to make them aware of the latest technological advancement in the field of designing.

Computer Aided Design provides detailed information on Computer Aided Design, Computer Aided Design Software, Computer Aided Design and Manufacturing, Computer Aided Design and Engineering and more. Computer Aided Design is affiliated with Cam and Computer Aided Design.

Softwares in Use:

Based on the concept of CAD technology, many CAD software have been developed by software giants like Auto-desk Inc, Bentley, Dassult Systemes, Some of the leading software in the industry are Auto-CAD, Micro-station, CATIA, Pro-Engineer, Uni-graphics, Solid-Edge, STAAD Pro, Auto-Civil, Auto-desk Inventor and the list goes on and on.

Due to CAD facilities, the repetition of work are minimized, exact accuracy can be achieved; reproduction is not a problem now days. After conversion into digital format it can also be sent through electronic mail to any part of the world as an editable file. Due to availability of a lot of file formats, the same file can be opened and used in a variety of CAD software.

Computer Aided Design (CAD) Process:

In CAD, generally the drawings are done according to the dimensions given either in a hard copy like paper or it may have been mentioned in a raster or image file, which is a scanned copy of the paper drawing. If the source drawing is a hard copy, then putting the hard copy by the side and referring to the same does the drawings. But this is a cumbersome process. So another process has been developed in which, the hard copy is scanned and the same is attached into the drawing platform say, Auto CAD. Then it becomes easier to draw the elements. This type of draughting is called as on-line draughting.

Area of Use:

As it is easy to work with cad software the authorities, engineers, draughts- men in many part of the world have already begun to work with the most advanced facilities and technologies like CAD (Computer Aided Designing) for creation, modification, reproduction, safely store and enhancement of dynamism in their drawings, such as: Civil Engineering, Mechanical Engineering, Electrical Engineering, Electronics, Engineering, Architectural Engineering, Aerospace, Automobile, Manufacturing, Production, Plumbing, Piping, HVAC and Fashion Design etc...

Advantages and Disadvantages:

Modeling with CAD systems offers a number of advantages over traditional drafting methods that use rulers, squares, and compasses. For example, designs can be altered without erasing and redrawing. CAD systems also offer "zoom" features analogous to a camera lens, whereby a designer can magnify certain elements of a model to facilitate inspection. Computer models are typically three dimensional and can be rotated on any axis, much as one could rotate an actual three dimensional model in one's hand, enabling the designer to gain a fuller sense of the object. CAD systems also lend themselves to modeling cutaway drawings, in which the internal shape of a part is revealed, and to illustrating the spatial relationships among a system of parts.

Other limitations to CAD are being addressed by research and development in the field of expert systems. This field derived from research done on artificial intelligence. One example of an expert system involves incorporating information about the nature of materials—their weight, tensile strength, flexibility, and so on—into CAD software. By including this and other information, the CAD system could then "know" what an expert engineer knows when that engineer creates a design. The system could then mimic the engineer's thought pattern and actually "create" a design. Expert systems might involve the implementation of more abstract principles, such as the nature of gravity and friction, or the function and relation of commonly used parts, such as levers or nuts and bolts. Expert systems might also come to change the way data is stored and retrieved in CAD/CAM systems, supplanting the hierarchical system with one that offers greater flexibility.

One of the key areas of development in CAD technologies is the simulation of performance. Among the most common types of simulation are testing for response to stress and modeling the process by which a part might be manufactured or the dynamic relationships among a system of parts. In stress tests, model surfaces are shown by a grid or mesh, that distort as the part comes under simulated physical or thermal stress. Dynamics tests function as a complement or substitute for building working prototypes. The ease with which a part's specifications can be changed facilitates the development of optimal dynamic efficiencies, both as regards the functioning of a system of parts and the manufacture of any given part. Simulation is also used in electronic design automation, in which simulated flow of current through a circuit enables the rapid testing of various component configurations.

The processes of design and manufacture are, in some sense, conceptually separable. Yet the design process must be undertaken with an understanding of the nature of the production process. It is necessary, for example, for a designer to know the properties of the materials with which the part might be built, the various techniques by which the part might be shaped, and the scale of production that is economically viable. The conceptual overlap between design and manufacture is suggestive of the potential benefits of CAD and CAM and the reason they are generally considered together as a system.

Recent technical developments have fundamentally impacted the utility of CAD/CAM systems. For example, the ever-increasing processing power of personal computers has given them viability as a vehicle for CAD/CAM application. Another important trend is toward the establishment of a single CAD-CAM standard, so that different data packages can be exchanged without manufacturing and delivery delays, unnecessary design revisions, and other problems that continue to bedevil some CAD-CAM initiatives. Finally, CAD-CAM software continues to evolve on a continuing basis in such realms as visual representation and integration of modeling and testing applications.

CAD – Employment Outlook:

From the smallest computer microchip to the tallest skyscraper, every product must first pass through a painstaking process of design and analysis. Computers are making this process easier.

Computer-aided design (CAD) joins the power of the computer with the creativity and skills of the engineer, architect, designer, and drafter. The National Science Foundation suggests that CAD "many represent the greatest increase in productivity since electricity." This article examines some of the applications of this technology, its implications for the workers who use it, and opportunities it may offer for jobs in the future. Computer-aided design is not a new technology. The aerospace and automotive industries developed their own software packages to assist in product design and development over 20 years ago. And commercial CAD systems have been available since 1964. These early systems, however, used expensive mainframe computers that only the largest companies could afford. But recent advances in computer technology, particularly the introduction of mini-and microcomputers, have brought this technology within the reach of a host of potential users. The electronics industry, from computer makers to component manufacturers, is already a major user of CAD systems, and architectural, engineering, and construction firms are increasing their use of these systems to prepare designs, maps, and technical illustrations.

In the simpler forms of CAD, the drafter, working from an engineer's or architect's rough sketch, creates drawings on a computer screen. The pens, inks, compasses, and other tools used by drafters for generations are replaced by a keyboard, graphics tablet, digitizer, and light pen. Instead of a line of ink on paper, a line of glowing phosphorus appears on a video console. Through a series of programmed commands, the drafter can produce finished drawings in much less time and of a higher quality than those produced manually.

People frequently call CAD systems word processors for drafters. And, in fact, many of the word processor's advantages find counterparts in CAD systems. John Murray, an engineer with General Motors, jokes that, as with word processing equipment, "one of the things that works the best is the eraser." An error on the computer screen can easily be corrected with a few keystrokes. To correct a manual drawing takes much longer. To simplify this process still further, some of the more advanced CAD software packages are programmed to detect errors during the drafting process and inform the user that the data or design is incorrect. Most CAD systems, irrespective of the particular industry for which they are developed, offer four basic functions that greatly enhance the productivity of the drafter or designer.

* Replication--the ability to take part of an image and use it in other areas when the design or drawing has repetitive features;

* Translation--the ability to transfer features from one part of the screen to another;

* Scaling--the ability to change the size of one part of the design in relation to another;

* Rotation--the ability to turn the design on the screen so that it can be examined from different angles and perspectives.

When drafters and designers do their work on a CAD system, the drawings are stored in a central data base. The advantages here are several. First, the handy reference to previous drawings enables the operator to recall and modify a design whose features closely resemble a present assignment rather than start from scratch. Secondly, the data base encourages communication between the design and production staff. Working from the same data will greatly reduce the paper flow within a factory or office. Several sources interviewed for this article referred to the paperless factory of the future that CAD will permit. Thirdly, these stored designs serve as the basis for more complex applications of computer-aided design. These applications generally fall under another acronym--CAE--or computer- aided engineering. Using the same hardware that is used to draft a design, engineers are able to subject these designs to a battery of tests and analyses. The computer enables the engineer to simulate a variety of conditions or stresses to which a product may be subjected. For example, a designer or drafter in the automotive industry may design an axle according to an engineer's rough sketch. The engineer, working at another computer work station, will subject the axle to varying combinations of simulated conditions and weights. These computer simulations can cut the time between design and production; under older technologies, an actual prototype of the product or part would be fabricated, tested, redesigned, and reproduced until the engineer was satisfied with its performance. This reduction in development time should decrease costs and increase productivity.

COMPUTER AIDED MANUFACTURING (CAM):

Computer-aided manufacturing (CAM) is the use of computer-based software tools that assist engineers and machinists in manufacturing or prototyping product components and tooling. Its primary purpose is to create a faster production process and components and tooling with more precise dimensions and material consistency, which in some cases, uses only the required amount of raw material (thus minimizing waste), while simultaneously reducing energy consumption. CAM is a programming tool that makes it possible to manufacture physical models using computer-aided design (CAD) programs. CAM creates real life versions of components designed within a software package. CAM was first used in 1971 for car body design and tooling.

Overview:

Traditionally, CAM has been considered as a numerical control (NC) programming tool wherein three-dimensional (3D) models of components generated in CAD software are used to generate CNC code to drive numerically controlled machine tools.

Although this remains the most common CAM function, CAM functions have expanded to integrate CAM more fully with CAD/CAM/CAE PLM solutions. As with other “Computer-Aided” technologies, CAM does not eliminate the need for skilled professionals such as Manufacturing Engineers and NC Programmers. CAM, in fact, both leverages the value of the most skilled manufacturing professionals through advanced productivity tools, while building the skills of new professionals through visualization, simulation and optimization tools.

Early Use of CAM:

The first commercial applications of CAM were in large companies in the automotive and aerospace industries for example UNISURF in 1971 at Renault for car body design and tooling.

Historical shortcomings:

Historically, CAM software was seen to have several shortcomings that necessitated an overly high level of involvement by skilled CNC machinists. Fallows created the first CAM software but this had severe shortcomings and was promptly taken back into the developing stage. CAM software would output code for the least capable machine, as each machine tool interpreter added on to the standard g-code set for increased flexibility. In some cases, such as improperly set up CAM software or specific tools, the CNC machine required manual editing before the program will run properly. None of these issues were so insurmountable that a thoughtful engineer could not overcome for prototyping or small production runs; G-Code is a simple language. In high production or high precision shops, a different set of problems were encountered where an experienced CNC machinist must both hand-code programs and run CAM software.

Integration of CAD with other components of CAD/CAM/CAE PLM environment requires an effective CAD data exchange. Usually it had been necessary to force the CAD operator to export the data in one of the common data formats, such as IGES or STL, that are supported by a wide variety of software. The output from the CAM software is usually a simple text file of G-code, sometimes many thousands of commands long, that is then transferred to a machine tool using a direct numerical control (DNC) program.

CAM packages could not, and still cannot, reason as a machinist can. They could not optimize tool paths to the extent required of mass production. Users would select the type of tool, machining process and paths to be used. While an engineer may have a working knowledge of g-code programming, small optimization and wear issues compound over time. Mass-produced items that require machining are often initially created through casting or some other non-machine method. This enables hand-written, short, and highly optimized g-code that could not be produced in a CAM package.

At least in the United States, there is a shortage of young, skilled machinists entering the workforce able to perform at the extremes of manufacturing; high precision and mass production. As CAM software and machines become more complicated, the skills required of a machinist advance to approach that of a computer programmer and engineer rather than eliminating the CNC machinist from the workforce.

Typical areas of concern:

■High Speed Machining, including streamlining of tool paths

■Multi-function Machining

■5 Axis Machining

■Ease of Use

Overcoming historical shortcomings

Over time, the historical shortcomings of CAM are being attenuated, both by providers of niche solutions and by providers of high-end solutions. This is occurring primarily in three arenas:

1. Ease of use

2. Manufacturing complexity

3. Integration with PLM and the extended enterprise

Ease in use

For the user who is just getting started as a CAM user, out-of-the-box capabilities providing Process Wizards, templates, libraries, machine tool kits, automated feature based machining and job function specific tailorable user interfaces build user confidence and speed the learning curve.

User confidence is further built on 3D visualization through a closer integration with the 3D CAD environment, including error-avoiding simulations and optimizations.

Manufacturing complexity

The manufacturing environment is increasingly complex. The need for CAM and PLM tools by the manufacturing engineer, NC programmer or machinist is similar to the need for computer assistance by the pilot of modern aircraft systems. The modern machinery cannot be properly used without this assistance.

Today's CAM systems support the full range of machine tools including: turning, 5 axis machining and wire EDM. Today’s CAM user can easily generate streamlined tool paths, optimized tool axis tilt for higher feed rates and optimized Z axis depth cuts as well as driving non-cutting operations such as the specification of probing motions.

Integration with PLM and the extended enterprise:

Today’s competitive and successful companies have used PLM to integrate manufacturing with enterprise operations from concept through field support of the finished product.

To ensure ease of use appropriate to user objectives, modern CAM solutions are scalable from a stand-alone CAM system to a fully integrated multi-CAD 3D solution-set. These solutions are created to meet the full needs of manufacturing personnel including part planning, shop documentation, resource management and data management and exchange.

Machining Process:

Most machining progresses through four stages, each of which is implemented by a variety of basic and sophisticated strategies, depending on the material and the software available. Those stages are:

Roughing: This process begins with raw stock, known as billet, and cuts it very roughly to shape of the final model. In milling, the result often gives the appearance of terraces, because the strategy has taken advantage of the ability to cut the model horizontally. Common strategies are zig-zag clearing, offset clearing, plunge roughing, rest-roughing.

Semi-finishing: This process begins with a roughed part that unevenly approximates the model and cuts to within a fixed offset distance from the model. The semi-finishing pass must leave a small amount of material so the tool can cut accurately while finishing, but not so little that the tool and material deflect instead of shearing. Common strategies are raster passes, waterline passes, constant step-over passes, pencil milling.

Finishing: Finishing involves a slow pass across the material in very fine steps to produce the finished part. In finishing, the step between one pass and another is minimal. Feed rates are low and spindle speeds are raised to produce an accurate surface.

Contour milling: In milling applications on hardware with five or more axes, a separate finishing process called contouring can be performed. Instead of stepping down in fine-grained increments to approximate a surface, the workpiece is rotated to make the cutting surfaces of the tool tangent to the ideal part features. This produces an excellent surface finish with high dimensional accuracy.

Computer Aided Manufacturing Software:

Computer Aided Manufacturing (CAM) is one of the software automation processes that directly convert the product drawing or the object into the code design, enabling the machine to manufacture the product. The CAM system is used in various machines like lathes or milling machines for product manufacturing purposes. It allows the computer work instructions to communicate directly to the manufacturing machines. This saves on time and money, in that the controls can all be routed directly to a computer or laptop system, where changes can be made with the click of a button.

It provides compatibility with any CAD file format including DXF, DWG and DGN Professional 2D Mechanical drafting and design. It allows easy 3D modeling and rendering options. The CAM software provides complete support for milling, drilling and lathing operations. It includes the setup wizard, the tool database and a dialog-free CAM palette. CAM software has developed in such a way that it has become quick, flexible machining with effective simulation. The 2D and 3D simulation is developed in the real time environment - a major advantage of the software. Load factor compensation for machine and tool, tool paths, automatic optimal tool paths and cumulative time are also major benefits in this CAM software.

Several software vendors like AutoDesk, EDC, PTC, GibbsCAM and CamSoft offer you the software with factors involving high quality, ease of use, and a reasonable price. EDS e-factory, EDS e-Vis, EDC FactoryCAD, PTC Pro/ENGINEER Advanced Assembly, and the API Toolkit are a few of the major software applications that are used in the CAM system.

Computer Aided Manufacturing provides detailed information on Applications of Computer Aided Manufacturing, Cam And Computer Aided Design, Computer Aided Design, Computer Aided Design Scanners and more. Computer Aided Manufacturing is affiliated with Computer Aided Design and Manufacturing.

CAD stands for Computer Aided Design, it used to stand for Computer Aided Drafting but was changed because as it improved, it evolved to do more than just drafting. It is also known as CAID - Computer Aided Industrial Design and CAAD - Computer Aided Architectural Design.

CAD can be used in a number of different ways, depending on the task at hand, the profession of the user, as well as the type of software that is run. CAD comes in a variety of systems, and each requires a different pattern of thought on how to use it to maximum benefit. In addition, each system's virtual components must also be designed in a different way.

CAD generally operates on computers that are Windows based, although some systems run on hardware that uses Unix operating systems and a few work with Linux. There are a few CAD systems e.g. Ocad and NX that provide multi-platform support and these include Windows, Linux, UNIX, and Mac OSX.

In order to use CAD it is generally not necessary to obtain any special hardware other than a high-end OpenGL based Graphics card. If you are going to be doing complex designs then you will need computers with high speed CPUs and large amounts of RAM. A computer mouse is used as the human-machine interface, although a pen and digitising graphics tablet can also be used. In the 21st century technology has expanded its wings in almost every sphere of knowledge and life style. Hence with the enhancement of technology has empowered Engineers and Designers to get the power to excel with CAD.

Due to the advancement of CAD (computer aided design) there is no painstaking workout of the engineers and draughts-men standing near the drawing board with a huge drafter and trying to draw their concepts.

Recreation of designs & drawings has become so easy today that it takes only an unimaginable fraction of a second. Sharing of a single platform helps the draughts man to divide the time consumption and hence increases the productivity.

Software providers today:

The 10 largest CAM software products and companies, by end-user payments in year 2008[1] are, sorted alphabetically:

■CATIA from Dassault Systèmes

■Cimatron from Cimatron group

■Edgecam from Planit, formerly Pathtrace

■Mastercam from CNC Software

■NX formerly Unigraphics, from Siemens PLM Software

■Powermill from Delcam

■Pro/E from PTC

■Space-E/CAM from NDES, formerly Hitachi Zosen.

■Tebis from Tebis AG

■WorkNC from Sescoi

Other CAM products and companies are BobCAD, CAMWorks from Geometric Technologies, Inc., Dolphin, ESPRIT from DP Technology, GCAM, GIBcam, GibbsCAM, MazaCAM, MetaCAM,OneCNC, SUM3D, SurfCAM, T-FLEX, TopSolid from Missler and VisualMILL from MecSoft.

Areas of usage

■Aerospace Engineering

■Automotive Engineering

■Mechanical Industries

■electronic design automation, CAM tools prepare printed circuit board (PCB) and integrated circuit design data for manufacturing.

Markets and Applications

Within these enterprises, CAD is only one member of a family of Computer based technologies that is altering the nature of American manufacturing. Computer-aided manufacturing (CAM) is usually mentioned in the same breath as computer-aided design. This juxta position, CAD/CAM, refers to the capability of systems to design a part or product, devise the essential production steps, and transmit this information electronically to manufacturing equipment, such as robots. These design and manufacturing tools may, in turn, be linked to management information systems (MIS), which enable managers to monitor closely all aspects of a company's operations.

Implications for Employment

Technological innovations invariably prompt questions as to how these changes will affect employment. Implicit in many of these questions is the notion that the introduction of new technologies will lead to the elimination of certain jobs or at least to significant changes in the way these jobs will be performed. Among those occupations directly affected by CAD, concerns focus upon drafting and design jobs.

Drafting shops are traditionally a bottleneck in many industries. Pen and ink drawings take a long time to produce. Once complete, the drawings must be presented to the engineer or architect for review and analysis. The ability of CAD systems to produce drawings much faster than manual techniques would seem to reduce the need for drafters in the long run. Dr. Donald Hecht, president of the California College of Technology in Anaheim, a technical school that trains students in computer-aided design and drafting, urges a more cautious appraisal. "I hesitate to make such straight-line predictions," he says, "particularly when dealing with computer-based technologies." Hecht believes that the reduction in drafting time and the consequent increases in productivity that CAD affords may foster a greater emphasis upon new product design and development.

CATIAP3V5

Introduction:

CATIA (Computer Aided Three-dimensional Interactive Application) is a multi-platform CAD/CAM/CAE commercial software suite developed by the French company Dassault Systemes and marketed worldwide by IBM. Written in the C++ programming language, CATIA is the cornerstone of the Dassault Systemes product lifecycle management software suite. CATIA competes in the CAD/CAM/CAE market with Siemens NX, Pro/ENGINEER, Autodesk Inventor and SolidEdge.

Several thousands of companies in multiple industries Worldwide have already chosen the Virtual Design capabilities of CATIA products to ensure their products Real Success. CATIA delivers solutions for the enterprise from large OEMs through their supply chains to Small and Medium Businesses.

CATIA V5 is the leading solution for product excellence. It addresses all manufacturing organizations, from OEMs, through their supply chains, to small independent companies. The range of CATIA V5’s capabilities allows for its application in a wide variety of industries, from aerospace, automotive, industrial machinery, electrical, electronics, shipbuilding, plant design, and consumer goods, to jewelry and clothing.

CATIA V5 is the only solution that covers the complete product development process, from product concept specifications through to product-in-service, in a fully integrated manner. Based on an open, scalable architecture, it facilitates true collaborative engineering across the multidisciplinary extended enterprise, including style and form design, mechanical design, equipment and systems engineering, digital mock-up management, machining, analysis, and simulation. By enabling enterprises to reuse product design knowledge and accelerate development cycles, CATIA V5 helps companies speed-up their response to market needs.

In conjunction with ENOVIA for collaborative product lifecycle management, SIMULIA for engineering quality and DELMIA for production performance, CATIA V5 is a key component of V5 PLM.

Features:

Commonly referred as a 3D Product Lifecycle Management software suite, CATIA supports multiple stages of Product development (CAx), from Conceptualization, Design (CAD), Manufacturing (CAM), and Engineering (CAE).

CATIA can be customized via application programming interfaces (API). V4 can be adapted in the Fortran and C programming languages under an API called CAA. V5 can be adapted via the Visual Basic and C++ programming languages, an API called CAA2 or CAA V5 that is a component object model (COM)-like interface. Although later versions of CATIA V4 implemented NURBS, V4 principally used piecewise polynomial surfaces. CATIA V4 uses a non-manifold solid engine.

CatiaV5 features a parametric solid/surface-based package which uses NURBS as the core surface representation and has several workbenches that provide KBE support. V5 can work with other applications, including Enovia, Smarteam, and various CAE Analysis applications.

The version used in the current project is CATIA V5R17. It extends the unique 2D/3D associative approach for conceptual design and extends the 3D master approach by enabling the fast and convenient display of product information, such as tolerances and annotations, in a familiar drawing layout within the 3D environment. It boosts conceptual design within the 3D environment by enabling designers to easily create in-context 2D sketches from the automatic detection of existing 3D geometry displayed in the view background. Efficient, comprehensive, and standards-compliant CATIA V5 drafting capabilities always guarantee high quality when realizing drawing layouts and dress-up, whether immersed in 3D or in a separate drawing document. It is continually enhanced and updated to meet specialized needs, such as support for new customized symbols, strokes, and open-type fonts.

CATIA V5R17 promotes 3D as the master reference for part and product definition. Designers can define and manage standards-compliant tolerance specifications and annotations linked to the 3D geometry, making them directly reusable for manufacturing planners and to be shared throughout the enterprise. Designers can easily present and share 3D tolerancing and annotation in a familiar drawing layout embedded in the 3D environment. V5R17 enables the rapid creation of associative views from Functional Tolerancing & Annotation views or captures. Users benefit from a more productive 3D annotation definition and layout process by realizing specific operations in a single step, such as directly managing the view ratio property for 3D annotation.

CATIA V4 to V5/V6 Conversion:

CATIA V5 and V6 can directly use the CATIA V4 models, but changes in the CATIA data structure requires data conversion from CATIA V4 to V5/V6. This is due to both a change in geometric kernel between CATIA V4 and CATIA V5, and changes in the CAD data structure between CATIA V5 and CATIA V6. Dassault Systemes provides utilities to convert CATIA V4 data to CATIA V5 with a one-to-one mapping. Still, cases show that there can be issues in the data conversion from CATIA V4 to V5, from either differences in the geometric kernel between CATIA V4 and CATIA V5, or by the modelling methods employed by end users.

Experiment results show that there can be data loss during the conversion (from 0% to 90%). The percentage loss can be minimized by using the appropriate pre-conversion clean-up, choosing the appropriate conversion options, and clean-up activities after conversion.

Engineering service providers have solutions, but mostly they are unique to a particular company and its processes / standard of modeling method. A common solution for 100% data conversion has yet to be devised. It is important to note that ANY change from one modeling kernel to another would cause similar problems; this issue is not unique to CATIA.

Notable Industries using CATIA:

CATIA is widely used throughout the engineering industry, especially in the automotive and aerospace sectors.

Aerospace:

The Boeing Company used CATIA V3 to develop its 777 airliner, and is currently using CATIA V5 for the 787 series aircraft. They have employed the full range of Dassault Systemes' 3D PLM products — CATIA, DELMIA, and ENOVIA LCA — supplemented by Boeing developed applications.[9] Chinese Xian JH-7A is the first aircraft developed by CATIA V5, when the design was completed on September 26, 2000. European aerospace giant Airbus has been using CATIA since 2001.[10] Canadian aircraft maker Bombardier Aerospace has done all of its aircraft design on CATIA.[11] The Brazilian aircraft company, EMBRAER, use Catia V4 and V5 to build all airplanes. The British Helicopter company, Westlands, use CATIA V4 and V5 to produce all their aircraft. Westlands is now part of an Italian company called Finmeccanica the joined company calls themselves AgustaWestland.

Automotive:

Many automotive companies use CATIA to varying degrees, including BMW, Porsche, Daimler AG, Chrysler, Audi,[12] Volkswagen, Bentley Motors Limited, Volvo, Fiat, Benteler AG, PSA Peugeot Citroën, Renault, Toyota, Ford, Scania, Hyundai, Škoda Auto, Tesla Motors, Proton, Tata motors and Mahindra & Mahindra Limited. Goodyear uses it in making tires for automotive and aerospace and also uses a customized CATIA for its design and development. Many automotive companies use CATIA for car structures — door beams, IP supports, bumper beams, roof rails, side rails, body components — because CATIA is very good in surface creation and Computer representation of surfaces.

Shipbuilding:

Dassault Systems has begun serving shipbuilders with CATIA V5 release 8, which includes special features useful to shipbuilders. GD Electric Boat used CATIA to design the latest fast attack submarine class for the United States Navy, the Virginia class.[13] Northrop Grumman Newport News also used CATIA to design the Gerald R. Ford class of supercarriers for the US Navy.[14]

Other:

Architect Frank Gehry has used the software, through the C-Cubed Virtual Architecture company, now Virtual Build Team, to design his award-winning curvilinear buildings.[15] His technology arm, Gehry Technologies, has been developing software based on CATIA V5 named Digital Project.[16] Digital Project has been used to design buildings and has successfully completed a handful of projects.

MASTERCAM

History:

Founded in Massachusetts in 1983,[1] CNC Software, Inc. is one of the oldest developers of PC-based computer-aided design / computer-aided manufacturing (CAD/CAM) software. They are one of the first to introduce CAD/CAM software designed for both machinists and engineers.

Introduction:

Mastercam, CNC Software’s main product, started as a 2D CAM system with CAD tools that let machinists design virtual parts on a computer screen and also guided computer numerical controlled (CNC) machine tools in the manufacture of parts. Since then, Mastercam has grown into the most widely used CAD/CAM package in the world.[2] CNC Software, Inc. is now located in Tolland, Connecticut.

Mastercam’s comprehensive set of predefined toolpaths—including contour, drill, pocketing, face, peel mill, engraving, surface high speed, advanced multiaxis, and many more—enable machinists to cut parts efficiently and accurately. Mastercam users can create and cut parts using one of many supplied machine and control definitions, or they can use Mastercam’s advanced tools to create their own customized definitions.

Mastercam also offers a level of flexibility that allows the integration of 3rd party applications, called C-hooks, to address unique machine or process specific scenarios. Mastercam's name is a double entendre: it implies mastery of CAM (computer-aided manufacturing), which involves today's latest machine tool control technology; and it simultaneously pays homage to yesterday's machine tool control technology by echoing the older term master cam, which referred to the main cam or model that a tracer followed in order to control the movements of a mechanically automated machine tool.

Mastercam Product Levels:

With the release of Mastercam X (10), the application became a true Windows-based application, as opposed to one ported over from DOS. It also represented a fundamental shift in the way the application was configured. Mastercam X2 provided many enhancements over the previous version and adopted a true Windows application feel. Mastercam supports many types of machines, each with a choice of levels of functionality, as well as offers optional add-ins for

solid modeling, 4-axis machining, and 5-axis machining. The following list describes the Mastercam product levels:

• Design—3D wireframe geometry creation, dimensioning, importing and exporting of non-Mastercam CAD files (such as AutoCAD, SolidWorks, Solid Edge, Inventor, Parasolid, etc.).

• Mill Entry—Includes Design, plus various toolpaths (top construction and tool planes only), posting, backplot, verify.

• Mill, Level 1—Includes Mill Entry, plus surface creation, many additional toolpaths (for all construction and tool planes), highfeed machining, toolpath editor, toolpath transforms, stock definition.

• Mill, Level 2—Includes Mill, Level 1, plus additional toolpaths, toolpath projection, surface rough and finish machining, surface pocketing, containment boundaries, check surfaces.

• Mill, Level 3—Includes Mill, Level 2, plus 5-axis wireframe toolpaths, more powerful surface rough and finish machining, multiaxis toolpaths.

• 5-Axis add-on—5-Axis roughing, finishing, flowline multisurface, contour, depth cuts, drilling, advanced gouge checking.

• Lathe Entry—3D wireframe geometry creation, dimensioning, importing and exporting of non-Mastercam CAD files (such as AutoCAD, SolidWorks, Solid Edge, Inventor, Parasolid, etc.), various toolpaths, backplot, posting.

• Lathe, Level 1—Includes Lathe Entry, plus surface creation, C-axis toolpaths, stock definition, stock view utility.

• Router Entry—3D wireframe geometry creation, dimensioning, importing and exporting of non-Mastercam CAD files (such as AutoCAD, SolidWorks, Solid Edge, Inventor, Parasolid, etc.), various toolpaths (top construction and tool planes only), toolpath transformation in top plane, backplot, verify, posting. CNC Software/Mastercam 2

• Router—Includes Router Entry, plus surface creation, rectangular geometry nesting, additional toolpaths (for all construction and tool planes), highfeed machining, toolpath editor, full toolpath transformations, stock definition.

• Router Plus—Includes Router, plus additional toolpaths, toolpath projection, surface rough and finish machining, surface pocketing, containment boundaries, check surfaces.

• Router Pro—Includes Router Plus, plus True Shape geometry nesting, 5-axis toolpath functionality, multiple surface rough and finish machining, multiaxis toolpaths, toolpath nesting.

• Wire—2D and 3D geometry creation, dimensioning, various 2-axis and 4-axis wirepaths, customizable power libraries, tabs.

• Art—Quick 3D design, 2D outlines into 3D shapes, shape blending, conversion of 2D artwork into machinable geometry, plus exclusive fast toolpaths, rough and finish strategies, on-screen part cutting.

The Router products are targeted to the woodworking industries but are virtually identical to the Mill line.

CNC Programming:

Programming is a means of defining Tool Movements, through the application of coded Letter Symbols. As shown in the figure, all the phases of production are included in the programming, beginning with the technical drawing and end with the final product.

CNC machines use a special programming language called GN-code (technical name: RS274). MasterCAM is a software that allows users to create GN-code programs that can be used to cut different geometric shapes on CNC machines. The main functions are:

(i) Describe the geometry of the part to be machined.

(ii) Create a tool database – this DB carries information about the available milling tools.

(iii) Create the GN-code program to cut the part.

(iv) Simulate the machining of the part (for visual verification of the program).

(v) Upload the program to the CNC machine controller.

Virtual Machining Process

Before commencement of the actual machining, the followings steps need to be considered and performed carefully.

1) Drawing Study:

Drawing study is the very first basic and important step of manufacturing. It is the process of understanding the components geometry, identifying the machining processes and knowing various other parameters which are all together required to convert that component from raw material to final finished product. Also special processes like coatings, polishing finishes etc. are all identified. Drawings are normally represented in sheets of ‘A’-series. Based on the size & geometry of the part, no of details, other specifications, etc., the ‘A’ sheet is used to represent it. Sometimes, based on the complexity of the part geometry, more than one sheet will also be used to provide all the details. Any mistake or error if arises while reading or understanding the drawing, it ruins the entire manufacturing process and finally the part gets rejected. So, one should have proper technical knowledge and sufficient experience for reading and understanding a Production Drawing. These drawings are generally read by Production In-charges or Shop floor Supervisors.

2) Development of Geometry CAD Model:

You can create the geometry in one of two ways:

(a) By using the graphical design interface provided by MasterCAM

(b) By making the design in a CAD software, e.g. CATIA, Pro/Engineer, SolidWorks, and saving it in a format that MasterCAM can import (safest format to use: IGES; other possible formats include STL, STEP)

Method (a) is useful if you want to cut a simple shape; although MasterCAM provides some functions to generate 3D curved surfaces, defining the geometry in this environment is not convenient. So: if you want to make a part where the entire shape is defined using volumes made by sweeping 2D profiles normal to the plane of the geometry, use method (a). If you have access to any CAD system, use method (b).

Method (b) generates the part by using a CAD system, and saved in any one of the Data Exchange Formats. Design the part (in, e.g. CATIA or SolidWorks). It is best if you already create the part such that the surfaces to machine are in the correct orientation and position for the machine. That is, the machining surfaces should be accessible from –Z direction, and the part should be located such that the covering, rectangular stock should be in the positive octant of the coordinate frame, with the corner at the origin.

In the current project, the model is developed using Catia V5R17.

Import the part into MasterCAM :-

MAIN MENU 􀃆 File 􀃆 Converters 􀃆 IGES 􀃆 Read File 􀃆 in the file browser, select file 􀃆 OK.

3) Identifying and Planning Process Sequence:

After developing the cad model, all the processes involved in manufacturing a that component need to be identified and the sequence of those processes must be planned. For example, a particular component involves some processes, such as, Rough milling, Facing, Finish milling, Rough Turning, Grinding, Drilling and Tapping, etc. Planning the sequence of all these processes depends on many factors such as;

a) Complexity of the operation

b) Material being used

c) Geometry of the part

d) Degree of closeness of tolerances

e) Sometimes availability of the machinery

f) Any Heat Treatment Process specified, etc.

Based on its geometry and features, the current component involve, four milling operations (viz.., one contour milling and three pocket milling operations). All these operations are carried out in two steps (i) Roughing and (ii) Finishing.

4) Planning of Tools (Tooling):

For the completion of a machining process in-time and with desired surface finish conditions, proper planning of the required tools must be adopted. After identifying the processes involved, we need to select which tools are suitable for each individual process. This planning of tools not only helps to complete the operation in-time, but also brings down the manufacturing cost to a greater extent. If the jobs to produced are of large quantity (e.g. nuts, bolts, automobile components, etc), then it is advisable to use indexable milling inserts, because inserts can machine more number of parts when compared to solid cutters. This automatically, reduces the tooling expenses.

The tool database present in the Mastercam software describes the geometry of tools available for use in the workshop. The path that a tool travels in order to cut a shape depends on the size of the tool; some other information about the tool is also important – for example, the length of the cutting teeth on a drill or an end mill constraints the depth of the hole these can cut. The main functions for the tool database are:

(i) Look for an existing tool that you may want to use

MAIN MENU 􀃆 NC Utils 􀃆 Def. Tools 􀃆 Library

The Tools Manager window comes up, listing all available tools. Suppose we want to look for a flat end-mill of small diameter (e.g. less than 6mm). We can use the filter as follows:

Click Filter. In the Tools list Filter window, click Endmill1 Flat (top left icon) [if you leave the mouse cursor above the icon, its name appears] 􀃆 Tool diameter: [less than] value: 6 􀃆 Unit masking: metric 􀃆 OK.

The tools Manager window will show all tools that match these criteria.

NOTE: by default, ALL TOOL TYPES are selected; you must click on each icon to DE-SELECT it.

The figure below shows that my search gave five tools matching my criteria; If I want to use a 5mm end mill, double click on this tool, and its details will be shown in a Define Tool window.

If the search results in no existing tool, and you would like to enter the data of a tool you have into the library: RIGHT-CLICK within the Tools Manager window 􀃆 Create new tool. This also pops up the Define Tool window; type the data for the new tool, and click Save to library...

In the current case, for all the four operations, Flat-End Mill type cutters of different radii are used.

5) Generation of Machining Tool path:

There are many different options and settings in generation of the tool path. Respective option must be chosen based on the requirement.

Using the Tool parameters tab, you can set the Spindle speed, Feed rate and Plunge rate; if you know the values, enter them; otherwise just use the default – you can modify these when you actually machine the part, on the CNC machine.

Hit OK, and if all goes well, the software will generate the tool path for you, and display it. Notice that the tool path where it is cutting is shown in different color than when it is moving up or down, and moving between pockets. Also notice how the tool path for removing the region inside the pocket is zig-zag, but the tool path also goes once around the contour of each pocket.

6) Verification of the Generated Tool Paths:

Once after proper tool paths with desired operations are developed, these are verified by simulating them one after the other, so that the final product after total machining can be viewed graphically.

In Mastercam, we can see a 3D animation of the cutting by the following method:

MAIN MENU 􀃆 Toolpaths 􀃆 Operations 􀃆 The operations Manager window pops up; 􀃆 Verify, and then click the Machine button on Verify: simulation window. You can speed up the simulation by moving the slider to the right:

7) Job Stock Set-up:

This step defines the block from which you will cut the final part. It is essential to create the cutting plan. This enables proper viewing and understanding of the Virtual Machining process. This step has to be performed prior to the tool path verification process.

MAIN MENU 􀃆 Toolpaths 􀃆 Job Setup 􀃆 in the Job Setup window, Click Bounding Box [Window will vanish], MasterCAM will prompt you to select the entities:

All 􀃆 Entities 􀃆 Done

Job setup window re-appears, and the size of the bounding box is displayed in the correct boxes 􀃆 OK.

You will see the bounding box around the part (different colored lines) 4

8) Completion of the Given Task:

Following all the above operations properly with proper attention and care leads to completion of the task as per the specifications. After completion of all these steps, the NC code part programme must be developed for real time machining.

The tool path generated by MasterCAM has all information required to control a CNC machine tool to cut the part. However, different CNC machines use slightly different versions of GN-code. The conversion of the machining data to the GN-code specific for a particular CNC machine is called Post-Processing. The exact format of the GN-code is stored in different post-processing files, and the system will use whichever post-processing format you select.

Later, the generated NC-Part file is subjected to proper Header- Footer changes before being transferred into the CNC machine controller. You can set the communications settings for your CNC machine controller, and if your PC is connected to the CNC machine controller, the program will be uploaded to the CNC machine. Else, the program can also be transferred using various external Data Transfer Devices.

CONCLUSIONS:

As the concept of virtual machining is not just viewing of the machining process graphically, it has to be carried out with atmost care. So, while performing virtual machining, the following precautions must be taken into consideration:

Ø No mistake or error should takes place while creating the model. All the dimensions and sizes must be maintained as given in the drawing.

Ø The model has to be converted into proper Data Exchange formats in which very less or no geometry losses occur.

Ø After importing the model into the CAM software, it should be transformed into proper orientation as per the machining convenience.

Ø While generating the tool paths for various operations, precautions should be followed keeping in mind, the real time machining hurdles, like spindle speed , feed, depth of cut, etc.

Ø It is always advisable that tool path for each operation is verified until you get visually satisfied.

Ø After generating the NC Code part file, it is mandatory that necessary Header- Footer changes are made before transforming it into the CNC machine controller.

REFERENCES:

1) Operational Manual of “Vertical Milling Machine. Model: BMV 50, Controller: Fanuc Series-OiMB”.

2) “CNC MACHINES” by B.S. Pabla, M.A. Adhithan.

3) “MECHATRONICS” by HMT.

4) “Automation Production Systems and Computer Integrated Manufacturing” by Mikell P. Groover.

5) www.wikipedia.com

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Saturday, 29 December 2012

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