Computer-aided design (CAD) is the use of a wide range of computer-based tools that assist engineers, architects, and other design professionals in their design activities. It is the main geometry authoring tool within the Product Lifecycle Management process and involves both software and sometimes special-purpose hardware. Current packages range from 2D vector-based drafting systems to 3D parametric surface and solid design modelers.
Theory and Application
CAD is used in a variety of ways within engineering companies. At its simplest level, it is a 2D wireframe package that is used to create engineering drawings. This has however, over the last decades, been overtaken by 3D parametric feature-based modeling. Component forms are created either using freeform surface modeling or solid modeling or a hybrid of the two. These individual components are then assembled into a 3D representation of the final product; this is called bottom-up design.