Computer-aided design, often abbreviated CAD, is the use of computers to design manufactured objects. Designs created and stored on a computer have many advantages over traditional pencil and paper documents. Using CAD software, for example, an engineer can change a design without laboriously revising hand-drawn plans. CAD programs also help organize large projects. Running CAD software on a computer network or on the Internet can enable several people—even people on opposite sides of the world—to work on different parts of a single design.
Architects design buildings using CAD software. Civil engineers use CAD for city planning and mapping. Mechanical engineers design parts of machines using CAD tools, and electrical engineers design printed circuit boards and computer chips with them. CAD is used in a variety of other professions as well, including landscape design and even fashion.
Many CAD methods replace traditional drafting techniques, which use pencils, rulers, T squares, and other tools to make paper documents. With CAD systems, the designer manipulates a mouse, an electronic pen, or a padlike device called a graphics tablet to create electronic drawings, which are then edited on a computer screen. Such methods are sometimes called computer-aided design and drafting (CADD).
CAD programs maintain highly precise mathematical models of the objects in a design. These models enable the designer to quickly enlarge, delete, copy, change, or move an object. The computer can perform some tasks automatically, such as simulating an electric circuit. The CAD program might also check for violations of design rules or specifications, generate a list of materials needed to fabricate (physically make) the final design, and even estimate its cost.
A number of CAD programs can handle only two-dimensional designs, but many programs support the design of three-dimensional objects. With three-dimensional CAD software, the designer can rotate objects on screen for viewing from any angle.
Engineers often use CAD in conjunction with computer-aided manufacturing (CAM). CAM programs directly control drilling, cutting, or milling machines, guiding the manufacture of an object or part. Integrated CAD/CAM programs enable completed designs to be fabricated extremely efficiently.
Aerospace and automotive companies developed some of the first CAD techniques in the 1960’s. At the time, the computers needed for CAD applications were so expensive that only large companies could afford them. Today, inexpensive personal computers handle many CAD functions.
See also Computer (Applications software) ; Computer graphics ; Industrial design (How an industrial designer works) ; Machine tool (Control of machine tools) ; Map (Production and reproduction) ; Mechanical drawing (Creating a drawing) .
