CAD is the process of drawing and modelling of diagrams and products in either two and three dimensions on a computer package, such as AutoCAD.
This serves many purposes: in the first instance CAD is used to produce manufacturing drawings of components, which the manufacture uses to produce components; secondly, these component drawings can be assembled together within the CAD package, in particular in a 3D view, enabling visualisation of assemblies before construction, and ensuring that one can assemble the components in the desired manner. Furthermore, this aids in fault finding in assemblies before manufacture and construction.
CAD is also used to design the layout of plant installations to provide engineers with a diagram of the recommended installation layout. It is therefore possible to receive details of the size of a plant room, for example, and design the layout of plant items to fit within the allocated space, or where there is limited space for a commissioning module to be installed in, for example, design a bespoke alternative arrangement of components, ensuring that the modules fit the designated space before arriving on site.