Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM)

I. Introduction

Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM), the application of computers in the design and manufacture of components used in the production of items such as automobiles and jet engines. CAD is software for creating precise engineering drawings. CAM adds a computer to a machine tool, such as a drill or a lathe. CAM engineers similarly use computer modeling to determine the best overall manufacturing procedures for use in an industrial plant, including the testing and handling of finished products. Engineers use CAD and CAM together to create the design in CAD on one computer, then transmit the design to a second computer that creates the part using CAM.

II. Computer-Aided Design

Engineers use CAD to create two- and three-dimensional drawings, such as those for automobile and airplane parts, floor plans, and maps. While it may be faster for an engineer to create an initial drawing by hand, it is much more efficient to change and distribute drawings by computer.

In the design stage, drafting and computer graphics techniques are combined to produce models of objects. Designers manipulate and test these models on video display screens until they incorporate the best balance of features, including ease of production and cost. The CAD information is then combined with CAM procedures through shared databases. Today, it is possible to perform the six-step "art-to-part" process with a computer. The first two steps in this process are the use of sketching software to capture the initial design ideas and to produce accurate engineering drawings. The third step is rendering an accurate image of what the part will look like. Next, engineers use analysis software to ensure that the part is strong enough. Step five is the production of a prototype, or model. In the final step the CAM software controls the machine that produces the part.

III. Computer-Aided Manufacturing

CAM uses a computer to control the manufacture of objects such as parts, which are most often made of metal, plastic, or wood. The manufacturing operations may include milling, drilling, lathing, and polishing. CAM software selects the best cutting tools for the material and sets the most effective cutting speed. The software generates an image, called a toolpath display, that shows how the tool will cut the material, much as print preview in a word-processing program displays a page before it is printed. The tool's path has three stages: the containment area, beyond which the tool may not cut; the rough cut, which removes large areas of material; and the surface finish cut, which removes gouges, produces a smooth finish, and cleans up the part.

IV. History

American Ivan Sutherland invented CAD in 1961 when he described a computerized sketchpad in a doctoral thesis while attending the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts. He designed CAD to replace the traditional drafting board and other tools drafters used, such as the ink pen, plastic stencil, and electric eraser. Early CAD software ran on large, expensive computers. Today, engineers can run CAD software on personal computers or UNIX workstations.

The earliest CAM software was a simple computer attached to a milling machine. Punching buttons on the computer's front panel programmed the software for the machine. Since the mid-1980s CAD and CAM have come closer together, as some CAM software operates within the CAD software programs instead of through shared databases.

Contributed By:

Ralph Grabowski, B.A. Sc.

President, XYZ Publishing, Ltd. Author of The Successful CAD Manager's Handbook and The Illustrated Autocad Quick Reference.

HOW TO CITE THIS ARTICLE

"Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM)," Microsoft® Encarta® Online Encyclopedia 2000