Computer-Aided Design and Manufacturing

Summary

Computer-aided design and manufacturing is a method by which graphic artists, architects, and engineers design models for new products or structures within a computer's virtual space. It is referred to by a host of terms related to specific fields—computer-aided drafting (CAD), computer-aided manufacturing (CAM), computer-aided design and drafting (CADD), computer-aided drafting/computer-aided manufacturing (CAD/CAM), and computer-aided drafting/numerical control (CAD/NC). The generic term computer-aided technologies is, perhaps, the most useful in describing computer technology as a whole. Used by professionals in many disciplines, computer-aided technology allows designers in traditional fields, such as architecture, to render and edit two-dimensional (2-D) and three-dimensional (3-D) structures. Computer-aided technology has also revolutionized once highly specialized fields, such as video game design and digital animation, into broad-spectrum fields that have applications ranging from the film industry to ergonomics.

Definition and Basic Principles

Computer-aided design and manufacturing is the combination of two different computer-aided technologies: computer-aided design (CAD) and computer-aided manufacturing (CAM). Although the two are related by their mutual reliance on task-specific computer software and hardware, they differ in how involved an engineer or architect must be in the creative process. A CAD program is a three-dimensional modeling software package that enables a user to create and modify architectural or engineering diagrams on a computer. CAD software allows a designer to edit a project proposal or produce a model of the product in the virtual space of the computer screen. CAD simply adds a technological layer to what is still, essentially, a user-directed activity.

CAM, on the other hand, is a related computer-aided technology that connects a CAD system to laboratory or machine-shop tools. There are many industrial applications for computer-directed manufacturing. One example of CAD/CAM might be when an automotive designer creates a three-dimensional model of a proposed design using a CAD program, verifies the physical details of the design in a computer-aided engineering (CAE) program, and then constructs a physical model via CAD or CAE interface with CAM hardware (using industrial lasers to burn a particular design to exact specifications out of a block of paper). In this case, the automotive designer is highly involved with the CAD program but allows the CAD or CAE software to direct the activity of the CAM hardware.

Background and History

CAD/CAM is, essentially, a modernization of the age-old process of developing an idea for a structure or a product by drawing sketches and sculpting models. Intrigued by the idea that machines could assist designers in the production of mathematically exact diagrams, Ivan Sutherland, a doctoral student at the Massachusetts Institute of Technology, proposed the development of a graphical user interface (GUI) in his 1963 dissertation, “Sketchpad: A Man-Machine Graphical Communication System.” GUIs allow users to direct computer actions via manipulation of images rather than by text-based commands. They sometimes require the use of an input device, such as a mouse or a light pen, to interact with the GUI images, also known as icons. Although it was never commercially developed, Sketchpad was innovative in that a user could create digital lines on a screen and determine the constraints and parameters of the lines via buttons located along the side of the screen. In subsequent decades, the CAD software package employed the use of a mouse, light pen, or touch screen to input line and texture data through a GUI, which was then manipulated by computer commands into a virtual, or “soft,” model.

In the twenty-first century, CAM is more or less the mechanical-output aspect of CAD work, but in the early days, CAM was developed independently to speed up industrial production on assembly lines. Patrick J. Hanratty, regarded as the father of CAD/CAM, developed the first industrial CAM using numerical control (NC) in 1957. Numerical control—the automation of machining equipment by the use of numerical data stored on tape or punched on cards—had been in existence since the 1940s, as it was cheaper to program controls into an assembly machine than to employ an operator. Hanratty's PRONTO, a computer language intended to replace the punched-tape system (similar to punch cards in that the automaton motors reacted to the position of holes punched into a strip of tape) with analog and digital commands, was the first commercial attempt to modernize numerical control and improve tolerances (limiting the range of variation between the specified dimensions of multiple machined objects).

How It Works

Traditionally, product and structural designers created their designs on a drawing board with pencils, compasses, and T squares. The entire design process was a labor-intensive art that demanded not just the ability to visualize a proposed product or structure in exact detail but also extensive artistic abilities to render what, up until that point, had been only imagined. Changes to a design, whether due to a client's specific needs or the limitations of the materials needed for construction, frequently required the designer to “go back to the drawing board” and create an entirely new series of sketches. CAD/CAM was intended to speed up the design and model-making processes dramatically.

Computer-Aided Design (CAD). CAD programs function in the same way that many other types of computer software function. One loads the software into a computer containing an appropriate amount of memory, appropriate video card, and appropriate operating system to handle the mathematical calculations required by the three-dimensional modeling process. There are quite literally hundreds of different CAD programs available for different applications. Some programs are primarily two-dimensional drawing applications, while others allow three-dimensional drawing, shading, and rendering. Some are intended for use in construction management, incorporating project schedules, or for engineering, focused on structural design. There are a range of CAD programs of varying complexity for computer systems of different capabilities and operating systems.

Computer-Aided Manufacturing (CAM). CAM, on the other hand, tends to be a series of automated mechanical devices that interface with a CAD program installed in a computer system—typically, but not exclusively, a mainframe computer. The typical progress of a CAD/CAM system from design to soft model might involve an automotive designer using a light pen on a CAD system to sketch out the basic outlines of suggested improvements for an existing vehicle. Once the car's structure is defined, the designer can then command the CAD program to overlay a surface, or “skin,” on top of the skeletal frame. Surface rendering is a handy tool within many CAD programs to play with the use of color or texture in a design. When the designer's conceptual drawings are complete, they are typically loaded into a computer-aided engineering program to ascertain the structural integrity and adherence to the requirements of the materials from which the product will ultimately be constructed. If the product design is successful, it is then transferred to a CAM program, where a product model, machined out of soft model board, can be constructed to demonstrate the product's features to the client more explicitly.

Advertisements for CAD programs tend to emphasize how the software will enhance a designer's imagination and creativity. They stress the many different artistic tools that a designer can easily manipulate to create a virtual product that is as close as possible to the idealized conceptual design that previously existed only in the designer's imagination. On the other hand, CAM advertisements stress a connection of the CAM hardware to real-world applications and a variety of alterable structural materials ranging from blocks of paper to machinable steel. The two processes have fused over time, partly because of the complementary nature of their intended applications and partly because of clients' need to have a model that engages their own imaginations, but certain aspects of CAD (those technological elements most appropriate to the creation of virtual, rather than actual, worlds) may eventually allow the software package to reduce the need for soft models in terms of product development.

CAD in Video Games and Film Animation. CAD work intended for video games and film animation studios, unlike many other types of designs, may intentionally and necessarily violate one basic rule of engineering—a design's form should never take precedence over its function. Industrial engineers also stress the consideration of ergonomics (the human body's requirements for ease, safety, and comfort when using a product) in the design process. In the case of the virtual engineer, the visual appeal of a video game or animation element may be a greater factor in how a design is packaged for a client. The animated film Snow White and the Seven Dwarfs was drawn by hand using live models between 1934 and 1937. The studio's founder, Walt Disney, sought ways to increase the animated characters' visual appeal. One technique he developed was to draw human characters with a larger-than-standard size head, ostensibly to make her appear to have the proportions of a child and, thus, to be more appealing to film viewers. To draw the character more easily, the actor playing Snow White, Marjorie Bell, was asked to wear a football helmet while acting. Later animation styles, influenced by designers' CAD animation software, could be even more exaggerated without needing a live model in an uncomfortable outfit. For example, the character of Jessica Rabbit in Amblin Entertainment's Who Framed Roger Rabbit? (1988) has a face and body designed exclusively for visual appeal rather than to conform to external world reality.

Applications and Products

CAD and CAD/CAM have an extensive range and variety of applications.

Medicine. In the medical field, for example, software that employs finite element methods (FEM; also called finite element analysis, or FEA), such as Abaqus FEA, allows designers to envision new developments in established medical devices—improving artificial heart valves, for example—or the creation of new medical devices. CAD software ideally allows a user to simulate real-world performance. CAD and CAM technologies have revolutionized the dentistry and prosthodontics industries. Modern scanning technology produces detailed, 3D images of the patient's condition, and CAD software can use that image to manufacture crowns, veneers, dentures, implants, and more.

Aerospace. CAD and CAM software increases the accuracy, safety, and reliability in developing parts and components used in aerospace research and production. Femap and NEi Nastran are software applications used for aerospace engineering. These programs can simulate the tensile strength and load capacity of various structural materials as well as the effect of weather on performance and durability.

Mechanical Engineering.Mechanical engineering firms sometimes use Siemens Digital Industries Software for CAM or CAE functions in order to create and revise structural models quickly.

Some forms of CAD have engineering applications that can anticipate a design's structural flaws to an even greater extent than an actual model might. One example of this application is SIMULIA, one of the simulation divisions of Dassault Systèmes that creates virtual versions of the traditional automobile safety tester—the crash-test dummy. The company's program of choice is Abaqus FEA, but it has altered the base software to use various specialized virtual models for a wider variety of weight and height combinations. In the real world, crash-test dummies are rather complex mechanical devices, but their virtual simulacra have been declared as effective in anticipating structural failure as the original models.

Animation. CAD programs have caused the rapid expansion and development of the animation industry—both in computer games and in film animation. Models of live animals and humans are generated using three-dimensional CAD software such as Massive and Autodesk. Graphic artists used Massive to create battle sequences in Peter Jackson's Lord of the Rings film trilogy. Autodesk Maya is often used for animated character designs. Autodesk 3ds Max is one of the forerunner programs in the video game industry. It allows a great deal of flexibility in rendering surfaces. Certain video games—such as Will Wright's Sims series as well as any number of massively multiplayer online role-playing games (MMORPGs) such as World of Warcraft, Second Life, and EverQuest—not only have CAD functions buried in the game's design but also accept custom content designed by players as a fundamental part of individualization of a character or role. A player must design a living character to represent him or her in the video game, including clothing, objects carried, and weapons used, and the process of creation is easily as enjoyable as the actual gameplay.

Avatar (2009) was envisioned by director James Cameron as a sweeping epic in much the same vein as George Lucas's original Star Wars trilogy (1977–83). Avatar was originally scheduled to start filming in 1997 after Cameron completed Titanic. Still, Cameron only started work on the computer-aided-technology aspects of the film in 2006, when he felt the technology was ready. Using a three-dimensional software animation package, an alien world was created. Most of the action depicted in the highly successful film Avatar occurs on a distant, toxic planet, Pandora. Pandora's ten-foot-tall blue creatures and the hybrid human-Na'vi avatar bodies were challenging for animators to render realistically, even using computer-aided technology.

Careers and Course Work

Careers in computer-aided design and manufacturing tend to be affected most obviously by the intended purpose of the designer's work. There could be significant differences between the coursework required of a medical device designer and that required of a film animation specialist. Aside from coursework in rapid visualization, CAD operation, graphic illustration, digital type and image manipulation, digital photography, new media, and three-dimensional modeling, those who wish to work with computer-aided technology should consider supplemental coursework in the field most relevant to their design area. Various institutes have CAD/CAM labs that provide experience and increase the awareness and capacities of engineers using CNC machines, CAD packages, computer-integrated manufacturing, and industrial robots and for those who wish to offer to teach to others in this field.

Social Context and Future Prospects

Computer-aided technologies, in general, are expected to keep developing and evolving. The possibilities of virtual reality continue to evolve as the need for structural and materials modeling increases. Some professionals describe the future of computer-aided design and manufacturing as “exponential productivity.” Rather than designers spending time working out the exact proportions and measurements needed for a given project and possibly making errors, CAM and CAD software can draw straight lines, evaluate numerical formulas for proportions, and edit mistakes in minutes. Designers can then spend more time on plans, improvements, and other tasks that improve the quality of their work.

In the twenty-first century, CAD and CAM are used in medicine, entertainment, 3D model printing, and more. Proprietary and open-source software licenses are widely available. If an organization uses many CAD or CAM systems, a computer-integrated manufacturing (CIM) system helps manage the technology.

Bibliography

Balamurugan, S. "CAD/CAM/CNC in Manufacturing Current Trends in Manufacturing (System) Engineering." ResearchGate, Nov. 2020, dx.doi.org/10.2139/ssrn.3767525.

Bi, Zhuming, and Xiaoqin Wang. Computer Aided Design and Manufacturing. Wiley, 2020.

Kerlow, Issac. The Art of 3D Computer Animation and Effects. 4th ed., Wiley, 2009.

Lake, Matthew. Technical Animation in Video Games. CRC Press, 2024.

Lee, Kunwoo. Principles of CAD/CAM/CAE Systems. Reading: Addison, 1999.

Mund, Ben. "CAD/CAM Options for Increased Shop Productivity." SME, 27 Jan. 2021, www.sme.org/technologies/articles/2021/february/cadcam-options-for-increased-shop-productivity. Accessed 15 July 2021.

Nyemba, Wilson R. Computer Aided Design: Engineering Design and Modeling Using AutoCAD. CRC Press, 2022.

Sapot, Bryan. "CAD – Computer-Aided Design: Manufacturing Explained." Mingo Smart Factory, 12 Jan. 2023, www.mingosmartfactory.com/cad-computer-aided-design-manufacturing-explained. Accessed 20 June 2024.

Sarkar, Jayanta. Computer Aided Design: A Conceptual Approach. CRC Press, 2017.

Schell, Jesse. The Art of Game Design: A Book of Lenses. 3rd ed., CRC, 2020.

Sengupta, Anindita. "Best General-Purpose CAD Software for Enterprise Businesses." G2, 2024, www.g2.com/categories/general-purpose-cad. Accessed 20 June 2024.

"Why Is Computer-Aided Design (CAD) Important to Manufacturing?" Godwin University, 21 July 2023, www.goodwin.edu/enews/why-is-computer-aided-design-cad-important. Accessed 20 June 2024.