What is computer-aided design or CAD? Definition and meaning

The definition and meaning of computer-aided design, also known as CAD, refers to the use of computer software that supports the design process. The software aids in the creation, modification, analysis and enhancing of a design. Many people mistakenly believe that computer-aided design refers just to drawings of a product – CAD refers to any use of software to help in the design process.

CAD software replaces drafting by hand with an automated process. People working in architecture today, MEP (mechanical, electrical and plumbing engineering), or structural engineering have probably used 2-D or 3-D CAD programs.

Computer-Aided DesignComputer-aided design makes designers’ work easier by enabling them to create, modify and optimize designs. MIT’s Impact Labs says: “Indeed with CAD, you can create anything! Ok, maybe not quite, but you can do a whole lot; and it provides you with visualization capabilities that makes it worth every effort you put into learning it.” (Image: impactlabs.mit.edu)

Europe’s largest manufacturing and electronics company, Siemens, makes the following comments regarding CAD on its website:

“Computer-aided design (CAD) is the use of computer programs to create two- or three-dimensional (2D or 3D) graphical representations of physical objects.”

“CAD software may be specialized for specific applications. CAD is widely used for computer animation and special effects in movies, advertising, and other applications where the graphic design itself is the finished product.”



“CAD is also used to design physical products in a wide range of industries, where the software performs calculations for determining an optimum shape and size for a variety of product and industrial design applications.”

Computer-aided design multi-dimensional viewing

The two- or three-dimensional diagrams can be rotated and viewed from several different angles, and even from the inside looking outward. Professional design renderings are generally printed out using a special plotter or printer.


CAD Modeling.gif
By Nicola L.K.Own work, CC BY-SA 3.0, Link


Computer-aided design is commonly used today for circuit design. The software may use system blocks to identify which components are required, or it may calculate which components are needed as well as laying out the circuit diagram.

Users of CAD programs say that one of their main advantages is being able to change different design ideas rapidly and easily.



Things that have been designed can often be built and tested virtually to determine whether they will work. This dramatically reduces the cost of modifying prototypes and purchasing parts.

Computer-aided design programs are currently used by an ever-growing number of different professions, including artists, drafters, engineers, architects, and others to create technical illustrations or precision drawings.

The concept of designing geometric shapes for objects – computer-aided geometric design (CAGD) – is very similar to CAD.

Computer-aided design using Solid EdgeRotary compressor, courtesy of the Ariel Corporation. Modeled and rendered in Solid Edge, a CAD program owned by Siemens. (Image: plm.automation.siemens.com)

Wide range of computer-aided design systems

Computer-aided design software today exists for all the major computer platforms, including Mac OS X, Unix, Windows and Linux. The user interface typically centers around a manually-held mouse – pens and digitizing graphic tablets are also available.

Some CAD systems allow for stereoscopic glasses for viewing three-dimensional models.

According to Techopedia:

“Most U.S. universities no longer require classes for producing hand drawings using protractors and compasses. Instead, there are many classes on different types of CAD software. Because hardware and software costs are decreasing, universities and manufacturers now train students how to use these high-level tools.”

“These tools have also modified design work flows to make them more efficient, lowering these training costs even further.”



Computer-aided design benefits

Better Visualization: of the finished product, sub-assemblies and component parts of a CAD system significantly speeds up the design process.

Better Accuracy: people who use CAD software make fewer mistakes.

Easier: CAD programs offer more robust and easier design documentation, including geometrics and dimensions, bills of materials, etc.

Re-Use: the software offers easy re-use of best practices and design data.

Autodesk Inventor computer-aided designAutodesk Invento, rated as one of the top-ten CAD programs on the market today, says it enables designers to create animations, snapshots, and exploded videos with a timeline-based story panel to manage it all. (Image: autodesk.co.uk)

Types of computer-aided design

There are many kinds of CAD, covering a vast range of uses – in each case, the design of their virtual components requires a different approach.

At the lower end of the 2D systems, there are several free and open source systems. These programs provide an approach to drawing without all the intricacies regarding scale and placement on the drawing sheet that hand drafting requires, because during the creation of the final draft it can be adjusted as required.

With 3D wireframe, which is basically an extension of 2D drafting, each line must be manually inserted into the drawing. The finished product has no mass properties associated with it, and you cannot add features, such as holes, directly to it.

The 3D wireframe model is an edge or skeletal representation of a real-life object. Models consist of lines, points, arcs, circles, and other curves that define the center lines or edges of objects.

3D ‘dumb’ solids are created in a way similar to manipulations of real world objects. Cylinders, prisms, spheres, and other basic 3D geometric forms have solid volumes added or taken away from them, as if cutting or assembling real-world objects. 2D projected views can be generated easily from the models.

With 3D solids, you do not usually have tools that easily allow from motion of components, set limits to their motion, or identify any interference between components.

More upmarket systems offer capabilities to incorporate more ergonomic, aesthetic and organic features into designs. Freeform surface modelling is frequently combined with solids that allow the designer to create products that fit the human form.

Product placement visualization through computer-aided designWith computer-aided design program, you can visualize where goods are placed on the shelves of supermarkets and other stores, move them around, and look at them from different angles.

History of computer-aided design

CAD can be traced back to 1957, when Dr. Patrick J. Hanratty – known as the ‘father of CAD/CAM’ – developed Pronto, the world’s first commercial numerical-control programming system. Sketchpad was created in 1960 by Ivan Sutherland, of MIT’s Lincoln Laboratory. Sutherland demonstrated the basic principles and feasibility of technical drawing using a computer.

Initially, CAD systems were simply replacements of drawing boards. Design engineers still worked in two dimensions to create technical drawings. Even so, with these early systems it was easier to modify and revise work done Over time, CAD software and hardware became more affordable for medium-sized firms.

3D wireframe features were developed in the 1960s. In 1969 Syntha Vision released Magi, the first commercially-available solid modeler program. NURBS (non-uniform rational Basis spline), a mathematical model used in computer graphics for generating and representing curves and surfaces, emerged in 1989 on Silicon Graphics workstations. CAS Berlin developed an interactive NURBS for personal computers – called NöRBS – in 1993.

A career in computer-aided designWould you like to become a computer-aided design technician? The UK National Career Service says you would work 35 to 40 hours per week, Monday to Friday, in a design office, either at a CAD design workstation or on a PC. Technicians who are working on construction and engineering design projects may be based on a building site.

In 1989, T-Flex introduced CADs based on parametric engines. With parametric modeling, the model is defined by parameters. If dimension values are changed in one place, changes automatically occur in other dimensions to preserve how all the elements in the design are related.

MCAD (mechanical computer aided-design) systems introduced the concept of constraints that enable the designer to define relations between different components in the assembly. Designers began to use a bottom-up approach – when parts are first created and then assembled together.

CAD systems are widely accepted today, and used throughout the industry. These systems, which once only worked within expensive workstations based mainly on UNIX operating systems, are today available off-the-shelf for use in PCs, laptops, tablets and smartphones.

CAD Technicians work environmentCAD technicians use software to create design plans, often for building and machinery. TotalJobs.com says that computer-aided design work may be called: “Computer aided industrial design (CAID), computer aided engineering (CAE), computer aided styling (CAS), or computer aided manufacturing (CAM).”

Three-dimensional modeling is the norm today, and can even be found in applications for the general public, like three-dimensional buildings modeling in Google Maps, garden planning (landscape gardening), and interior design.

CAD is an integral part of work done by employees in several industries. In fact, some of them – aerospace, architecture, automotive, cartography, civil engineering, fashion, interior design, landscaping, and hundreds of others – would not be able to function in our current business environment without CAD systems.

According to toptenreviews.com:

“Such ubiquity across a vast array of industries ensures the longevity and necessity of CAD software in today’s technology-driven world.”

Video – What is CAD?

If you ask people randomly in the street what CAD stands for, very few will answer with ‘computer-aided design’. This video explains how 3-D computer design helps people tackle problems from all angles.