Cad And Cam Technology Computer Science Essay

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Computer-aided design (CAD), also known as computer-aided drafting and design (CADD), is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer. CADD software, or environments, provides the user with input-tools for the purpose of streamlining design processes; drafting, documentation, and manufacturing processes. CADD output is often in the form of electronic files for print or machining operations. The development of CADD-based software is in direct correlation with the processes it seeks to economize; industry-based software (construction, manufacturing, etc.) typically uses vector-based (linear) environments whereas graphic-based software utilizes raster-based environments.

CADD environments often involve more than just shapes. As in the manual drafting of technical and engineering drawings, the output of CAD must convey information, such as materials, processes, dimensions, and tolerances, according to application-specific conventions.

CAD may be used to design curves and figures in two-dimensional (2D) space; or curves, surfaces, and solids in three-dimensional (3D) objects.

CAD is an important industrial art extensively used in many applications, including automotive, shipbuilding, and aerospace industries, industrial and architectural design, prosthetics, and many more. CAD is also widely used to produce computer animation for special effects in movies, advertising and technical manuals. The modern ubiquity and power of computers means that even perfume bottles and shampoo dispensers are designed using techniques unheard of by engineers of the 1960s. Because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics (both hardware and software), and discrete differential geometry.

The design of geometric models for object shapes, in particular, is often called computer-aided geometric design (CAGD).

Computer Aided Design is used in industry for a number of purposes and may be performed in the traditional two-dimensional world or in the more revealing three-dimensional world. For example, the floor layout of a manufacturing plant might be made from a bird's eye view perspective, which might be best served with a 2-D plan view. Or, the swing path of a curved door might be best modelled in 3-D so the opening and closing path can be viewed from many perspectives - to more clearly see potential interferences.

The technical core classes at EvCC have been structured to offer instruction in both perspectives. Three classes in are AutoCAD currently offered for lessons in two dimensional representations, and include instruction in the way in which engineering drawings are laid out, the basic and some of the more advanced design tools contained in the software, as well as detailed instruction exploring precision fits, tolerances, and geometric dimensioning and tolerancing. Two classes are offered in Solid Works, the first examining the basics involved in three dimensional representation, and the second exploring the use of these 3D models to build something on a 3-axis bench mill available at the college. Two courses are also offered in Catia, version 5, for those students seeking instruction on this popular CAD software. And finally, a course is offered in general computer literacy, to ensure that students are familiar with the Microsoft Office Suite.

OVERVIEW

Current computer-aided design software packages range from 2D vector -based drafting systems to 3D solid and surface modellers. Modern CAD packages can also frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle, even from the inside looking out. Some CAD software is capable of dynamic mathematic modeling, in which case it may be marketed as CADD - computer-aided design and drafting.

CAD is used in the design of tools and machinery and in the drafting and design of all types of buildings, from small residential types (houses) to the largest commercial and industrial structures (hospitals and factories).

CAD is mainly used for detailed engineering of 3D models and/or 2D drawings of physical components, but it is also used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components. It can also be used to design objects.

CAD has become an especially important technology within the scope of computer-aided technologies, with benefits such as lower product development costs and a greatly shortened design cycle. CAD enables designers to lay out and develop work on screen, print it out and save it for future editing, saving time on their drawings.

USES

Computer-aided design is one of the many tools used by engineers and designers and is used in many ways depending on the profession of the user and the type of software in question.

CAD is one part of the whole Digital Product Development (DPD) activity within the Product Lifecycle Management (PLM) process, and as such is used together with other tools, which are either integrated modules or stand-alone products, such as:

Computer Aided Engineering (CAE) and Finite Element Analysis

Computer-aided Manufacturing to Computer Numeric Control

Photo Realistic Rendering

Document management and revision control.

Product Data Management

CAD is also used for the accurate creation of photo simulations that are often required in the preparation of Environmental Impact Reports, in which computer-aided designs of intended buildings are superimposed into photographs of existing environments to represent what that locale will be like were the proposed facilities allowed to be built. Potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD.

TYPES

There are several different types of CAD. Each of these different types of CAD systems require the operator to think differently about how he or she will use them and he or she must design their virtual components in a different manner for each.

There are many producers of the lower-end 2D systems, including a number of free and open source programs. These provide an approach to the drawing process without all the fuss over scale and placement on the drawing sheet that accompanied hand drafting, since these can be adjusted as required during the creation of the final draft.

1. 3D wireframe is basically an extension of 2D drafting.

2. 3D "dumb" solids (programs incorporating this technology include AutoCAD in a way analogous to manipulations of real world objects. 

3. 3D parametric solid modelling requires the operator to use what is referred to as "design intent". The objects and features created are adjustable. Any future modifications will be simple, difficult, or nearly impossible, depending on how the original part was created.

TECHNOLOGY

A CAD model of a mouse.

Originally software for Computer-Aided Design systems was developed with computer languages such as FORTRON, but with the advancement of object-oriented programming methods this has radically changed. Typical modern parametric feature based modeler and freeform surface systems are built around a number of key C modules with their own APIs. A CAD system can be seen as built up from the interaction of a graphical user interface (GUI) with NURBS geometry and/or boundary representation (B-rep) data via a geometric modeling kernel. A geometry constraint engine may also be employed to manage the associative relationships between geometry, such as wireframe geometry in a sketch or components in an assembly.

Today, CAD systems exist for all the major platforms (Windows, Linux, UNIX and Mac OS X); some packages even support multiple platforms.

Right now, no special hardware is required for most CAD software. However, some CAD systems can do graphically and computationally expensive tasks, so good graphics card, high speed (and possibly multiple) CPUs and large amounts of RAM are recommended.

The human-machine interface is generally via a computer mouse but can also be via a pen and digitizing graphics tablet. Manipulation of the view of the model on the screen is also sometimes done with the use of a space mouse/Space Ball. Some systems also support stereoscopic glasses for viewing the 3D model.

EFFECTS

Beginning in the 1980s Computer-Aided Design programs reduced the need of draftsmen significantly, especially in small to mid-sized companies. Their affordability and ability to run on personal computers also allowed engineers to do their own drafting work, eliminating the need for entire departments. In today's world most, if not all, students in universities do not learn drafting techniques because they are not required to do so. The days of mechanical drawings are almost obsolete. Universities such as New Jersey Institute of Technology no longer require the use of protractors and compasses to create mechanical drawings, instead there are several classes that focus on the use of CAD software such as Pro Engineer or IDEAS-MS.

Another consequence had been that since the latest advances were often quite expensive, small and even mid-size firms often could not compete against large firms who could use their computational edge for competitive purpose Today, however, hardware and software costs have come down. Even high-end packages work on less expensive platforms and some even support multiple platforms. The costs associated with CAD implementation now are more heavily weighted to the costs of training in the use of these high level tools, the cost of integrating a CAD/CAM/CAE PLM using enterprise across multi-CAD and multi-platform environments and the costs of modifying design work flows to exploit the full advantage of CAD tools. CAD vendors have effectively lowered these training costs. These methods can be split into three categories:

Improved and simplified user interfaces. This includes the availability of "role" specific tailorable user interfaces through which commands are presented to users in a form appropriate to their function and expertise.

Enhancements to application software. One such example is improved design-in-context, through the ability to model/edit a design component from within the context of a large, even multi-CAD, active digital mock-up.

User oriented modeling options. This includes the ability to free the user from the need to understand the design intent history of a complex intelligent model.

Computer-Aided Design is an established international journal that provides engineers, designers and computer scientists in academia and industry with key papers on research and developments in the application of computers to the design process.

Computer-Aided Design invites papers reporting new research and novel or particularly significant applications within a wide range of topics, including:

• CAD in conceptual design

• Design automation and optimization

• AI in design

• Geometric methods and applied computational geometry

• Surface and solid modelling

• Parametric, constraint-based, and feature modelling

• CAD interfaces to testing and analysis, including finite-element methods

• Design and planning for manufacturing, including numerical control, rapid prototyping and robotics

• Design and planning for assembly, maintainability, recycling etc

• Engineering data management and exchange, including design databases, component selection, product models, and life-cycle modelling

• Space and facilities planning and layout

• CAD user interfaces, including computer graphics, virtual and augmented reality

• Significant benchmarks, APIs, formats and standards in CAD

Contributions are acceptable across a wide range of disciplines, including:

• Mechanical and production engineering

• Civil engineering, architecture and building

• Industrial and aesthetic design

Papers in areas such as electrical and chemical engineering are also welcome provided they have a significant geometric component, and present developments likely to be of interest across other areas of CAD; Computer-Aided Design does not cover topics such as logic and process design.

CAD USAGE IN SCREENING, DAIGNOSTIC MAMMOGRAPHY INCREASES: STUDY

The use of computer-aided detection (CAD) is increasing, in both screening and diagnostic mammography, according to a study in the October issue of the Journal of the American College of Radiology (www.jacr.org). CAD software systems highlight and alert the radiologist of abnormal areas of density, mass or calcification on a digitized mammographic image (of the breast) that may indicate the presence of cancer.

CAD software programs

General purpose CAD software

Architectural CAD software

3D rendering software

Solid modelling CAD software

CAD/CAM/CAE software

Mechanical CAD (MCAD)

Facility management CAD

 

BENEFITS OF COMPUTER AIDED DESIGN

In the field of product development there are often immense costs associated with the testing of new products. Every new product must undergo at least a small measure of physical testing - not only to ensure that it meets minimum safety standards but also to ensure that it will successfully operate under the range of conditions to which it can expect to be exposed. For instance, the wing of an aeroplane just undergo stress tests to ensure that it will retain its integrity even under the most gruelling weather and turbulence conditions before it is approved for use.

Unfortunately, this testing can be ruinously time-consuming and expensive. If an aeronautical company has to physically build dozens of wings in the course of testing a new design then the final cost and time scale of the project can be far higher than projected.

Fortunately, there is no need to physically test all of these designs. Instead, developers can run virtual stress tests using computer-aided design, substituting a wind tunnel for a CAD application that can simulate the same conditions.

The benefits of virtual simulations are obvious. In addition to a reduction in the cost of product development and the time required to run tests there is also the advantage that conceptual designs can be modified instantly as the tests progress.

Perhaps one of the best examples of this versatility can be seen in the design of the aeroplane wing. The science of aerodynamics is complex, and it is often the case that certain wing shapes can create unexpected turbulence under certain conditions. When this occurs during physical testing it can be a challenge to discover the problem and make alterations. When running virtual tests using CAD, however, alterations to the design can be made quickly and easily, so new designs can be tested and retested until the problem is resolved.

New developments in CAD applications and technologies are regularly presented at such industry conferences as ICCAD, and in peer-reviewed journals such as Computer Aided Design and Applications. An introduction to the subject is available at NIST, and agency of the US Commerce Department.

BUSINESS APPLICATIONS FOR CAD

While Computer-Aided Design can be an excellent tool for performing stress tests on conceptual products, there are still more potential uses.

With the limiting factor of prototype manufacture removed, CAD allows the process of idea generation to become much more flexible. Enterprises can afford to be more open to new ideas and suggestions than in the past - from both employees and potential customers. Suggestions for new products can be quickly tested at a much lower cost than in the past.

* Augmentation

CAD opens up the possibility to make slight improvements on new product designs instantly. While this can be of great benefit in the design of a new product it can also be extremely useful for investigating possible improvements to existing products - or even reverse engineering and augmenting the products of competitors.

* Market Testing

Through designing new products using CAD it becomes possible to begin the process of market testing much earlier than in the past. Focus groups can be presented with virtual mock-ups of new products more quickly than would be possible with physical prototypes, and alterations can be made based on their feedback almost instantly. Since modifications can be made simply by entering new data into the CAD software, updated virtual mock-ups can be presented to the same audience for further feedback during the same session.

THE FUTURE OF CAD

Since the early development of Computer-Aided Design we have seen a trend towards increasing accessibility. When CAD applications became available for product development in the 1960s it was only the largest of enterprises that could afford to make use of the technology - the aerospace and automobile industries, for instance.

As computer technology developed, Computer-Aided Design made the move from dedicated systems to general-use personal computers, opening the door for smaller enterprises and individual users. Today it is possible to run most CAD software (and even some high-end 3D packages) on typical desktop PCs.

In the future we can expect further advances in 3D software packages, allowing users a more simple and intuitive experience. Perhaps most exciting for CAD users is the fact that the cost of 3D printing will steadily decline, opening up a whole new avenue in the product development process. Not only will CAD users be able to make instant modifications to their conceptual designs, but they will also be able to instantly create a physical prototype - solving an inherent drawback of virtual product development.

"CAD SOFTWARE IN THE FUTURE"

3D CAD software is today dominated by 3 vendors, Dassault, PTC and UGS.

Their 3D CAD software products are very similar - in fact so functionally similar that they now almost always avoid competing on 3D CAD functionality but instead focus almost exclusively on their PLM capabilities and "business process innovation".

Technical innovation in 3D CAD software seems to have flown out of the window as PLM stomped in through the door.

"COMPUTER AIDED MANUFACTURING"

Computer-aided manufacturing (CAM) is the use of computer software to control machine tools and related machinery in the manufacturing of work pieces. This is not the only definition for CAM, but it is the most common; CAM may also refer to the use of a computer to assist in all operations of a manufacturing plant, including planning, management, transportation and storage. 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 subsequent computer-aided process after computer-aided design (CAD) and sometimes computer aided engineering (CAE), as the model generated in CAD and verified in CAE can be input into CAM software, which then controls the machine tool.

APPLICATIONS OF COMPUTER AIDED MANUFACTURING

The field of computer aided design has steadily advanced over the past four decades to the stage at which conceptual designs for new products can be made entirely within the framework of CAD software. From the development of the basic design to the Bill of Materials necessary to manufacture the product there is no requirement at any stage of the process to build physical prototypes.

Computer-Aided Manufacturing takes this one step further by bridging the gap between the conceptual design and the manufacturing of the finished product. Whereas in the past it would be necessary for a design developed using CAD software to be manually converted into a drafted paper drawing detailing instructions for its manufacture, Computer-Aided Manufacturing software allows data from CAD software to be converted directly into a set of manufacturing instructions.

CAM software converts 3D models generated in CAD into a set of basic operating instructions written in G-Code. G-code is a programming language that can be understood by numerical controlled machine tools - essentially industrial robots - and the G-code can instruct the machine tool to manufacture a large number of items with perfect precision and faith to the CAD design.

Modern numerical controlled machine tools can be linked into a 'cell', a collection of tools that each performs a specified task in the manufacture of a product. The product is passed along the cell in the manner of a production line, with each machine tool (i.e. welding and milling machines, drills, lathes etc.) performing a single step of the process.

For the sake of convenience, a single computer 'controller' can drive all of the tools in a single cell. G-code instructions can be fed to this controller and then left to run the cell with minimal input from human supervisors.

BENEFITS OF COMPUTER AIDED MANUFACTURING

While undesirable for factory workers, the ideal state of affairs for manufacturers is an entirely automated manufacturing process. In conjunction with computer-aided design, computer-aided manufacturing enables manufacturers to reduce the costs of producing goods by minimizing the involvement of human operators.

In addition to lower running costs there are several additional benefits to using CAM software. By removing the need to translate CAD models into manufacturing instructions through paper drafts it enables manufactures to make quick alterations to the product design, feeding updated instructions to the machine tools and seeing instant results.

In addition, many CAM software packages have the ability to manage simple tasks such as the re-ordering of parts, further minimising human involvement. Though all numerical controlled machine tools have the ability to sense errors and automatically shut down, many can actually send a message to their human operators via mobile phones or e-mail, informing them of the problem and awaiting further instructions.

All in all, CAM software represents a continuation of the trend to make manufacturing entirely automated. While CAD removed the need to retain a team of drafters to design new products, CAM removes the need for skilled and unskilled factory workers. All of these developments result in lower operational costs, lower end product prices and increased profits for manufacturers.

PROBLEMS WITH COMPUTER AIDED MANUFACTURING

Unfortunately, there are several limitations of computer-aided manufacturing. Obviously, setting up the infrastructure to begin with can be extremely expensive. Computer-aided manufacturing requires not only the numerical controlled machine tools themselves but also an extensive suite of CAD/CAM software and hardware to develop the design models and convert them into manufacturing instructions - as well as trained operatives to run them.

Additionally, the field of computer-aided management is fraught with inconsistency. While all numerical controlled machine tools operate using G-code, there is no universally used standard for the code itself. Since there is such a wide variety of machine tools that use the code it tends to be the case that manufacturers create their own bespoke codes to operate their machinery.

While this lack of standardization may not be a problem in itself, it can become a problem when the time comes to convert 3D CAD designs into G-code. CAD systems tend to store data in their own proprietary format (in the same way that word processor applications do), so it can often be a challenge to transfer data from CAD to CAM software and then into whatever form of G-code the manufacturer employs.

Further information regarding computer-aided manufacturing can be found at the Berkeley CAM Research site, UC Irvine's CAM resource site and the National Institute of Standards and Technology (NIST) (PDF).

Computer-aided manufacturing (CAM), a form of automation where computers communicate work instructions directly to the manufacturing machinery. The technology evolved from the numerically controlled machines of the 1950s, which were directed by a set of coded instructions contained in a punched paper tape. Today a single computer can control banks of robotic milling machines, lathes, welding machines, and other tools, moving the product from machine to machine as each step in the manufacturing process is completed. Such systems allow easy, fast reprogramming from the computer, permitting quick implementation of design changes. The most advanced systems, which are often integrated with computer aided design systems, can also manage such tasks as parts ordering, scheduling, and tool replacement.

OVERVIEW

Chrome-cobalt disc with implants manufactured using CAM

Traditionally, CAM has been considered as a numerical control (NC) programming tool, wherein two-dimensional (2-D) or three-dimensional (3-D) models of components generated in CAD software are used to generate G-code to drive computer numerically controlled (CNC) machine tools. Simple designs such as bolt circles or basic contours do not necessitate importing a CAD file.

As with other "Computer-Aided" technologies, CAM does not eliminate the need for skilled professionals such as manufacturing engineers, NC programmers, or machinists. CAM, in fact, leverages both 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.

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. The 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 zigzag 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.

Finishingcil milling

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 work piece 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.

Software

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

CATIA from Dassault Systems

Cimatron from Cimatron group

Edgecam  from Planit formerly Pathtrace

Mastercam from CNC Software

NX from Siemens PLM Software

Powermill from Delcam

Pro/E from PTC

Space-E/CAM from NDES

Tebis from Tebis AG

WorkNC from Sescoi

Other CAM products and companies are Alphacam, BobCAD, CAMWorks, Dolphin, ESPRIT, GCAM, GIBcam, GibbsCAM, GoElan, MazaCAM, MetaCAM, OneCNC, SolidCAM, SprutCAM, SUM3D,SurfCAM, T-FLEX, TopSolid, Visual MILL, and VoluMill.

CAM Study Includes Diet Plans as Complementary and Alternative Medicine

The CAM study researched the use of United States adults and children of therapies used instead of, or in addition to, mainstream medicine. The study included 45 therapies that are considered complementary and alternative. In addition to therapies such as acupuncture and chiropractic, diet plans were defined as alternative or complementary. Diet plans included in the definition included the Atkins Diet, Macrobiotic Diet, Ornish Diet, Pritikin Diet, South Beach Diet, Vegetarian Diet and the Zone Diet.

Prospective study of CAM 17·1/WGA mucin assay for serological diagnosis of pancreatic cancer

Background

Serological tests for pancreatic cancer are little used, partly because such assays have proved insufficiently specific for screening. However, retrospective studies have reported results that compare well with commonly used scanning techniques. In this prospective study we assessed a new type of combined lectin/antibody enzyme-linked mucin assay, CAM 17·1, in a routine clinical setting.

Methods

Clinicians at a 1200-bed teaching hospital were encouraged to request the CAM 17·1 assay for any patient whose differential diagnosis included pancreatic cancer. Serum samples from 250 patients were tested during an 18-month period. Patients were followed up for at least 8 months. 75 patients who did not have symptoms of pancreatic cancer and had alternative diagnoses were also studied as a control group.

Computer-Aided Manufacturing System Engineering

A new type of computer-aided engineering environment is envisioned which will

improve the productivity of manufacturing/industrial engineers. This environment

would be used by engineers to design and implement future manufacturing

systems and subsystems. This paper describes work which is currently underway

at the United States National Institute of Standards and Technology (NIST) on

computer-aided manufacturing system engineering environments. The NIST

project is aimed at advancing the development of software environments and tools

for the design and engineering of manufacturing systems. The paper presents an

overall vision of the proposed environment, identifies technical issues which must

be addressed, and describes work on a current prototype computer-aided manufacturing system engineering environment.

NEW APPLICATIONS OF CAD/CAM

The integration of computer aided design and manufacturing (CAD/CAM) has been around for five decades. The technology, which was originally developed in the mid-1950s for use in the U.S. military, quickly spread to use by the automotive industry. As the technology grew in sophistication, so did its applications. Today, CAD/CAM technology is being used to manufacture everything from fine china and jet propulsion systems to-you guessed it-orthotic and prosthetic devices. Patients are already benefiting from digitally designed and created cranial helmets, AFOs, and multiple other orthotic applications, all or most of which have been made possible by the laser scanner, which has changed the way shapes are captured and enabled immense progress in the ways O&P practitioners are able to care for their patients.

New developments in CAD/ CAM continue to dazzle us as they debut. Chief among those, according to Randy Alley, BSc, CP, CFT, FAAOP, are contributions to upper-limb design. Alley is chair of the American Academy of Orthotists and Prosthetists (the Academy) CAD/CAM Society, which recently provided templates for the newer upper-limb interface designs to the industry's leading CAD/CAM providers.

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