What is CAD?
CAD (Computer Aided Design) is a method of using a computer programme to produce the digital equivalent of a drawing
The most common method of manufacturing design pre-cad was the drawing on paper – sometimes known as a blueprint because of a mid-1800’s method of reproducing drawings which resulted in a blue-tinged copy.
An essential was a drawing board, a simple term for something which could be an enormous and expensive beast, with counterbalanced arms precisely supporting drawing aids accurately located in the horizontal and vertical dimensions.
In my youth, at Vickers in Leeds, the drawing office took a complete floor of the office building with dozens of such cumbersome systems.
However, beginning in the mid-60’s CAD, starting with IBM’s Drafting System, became the design system of choice. By the mid-70s tools such as AutoCAD were born, extending the use of CAD into many professional sectors.
There are a great many advantages of CAD over conventional drawings, not least:
- The ability to draw very accurately
- The capability of creating 2D or 3D objects in a life-like representation
- Drawings produced in 3D can be spun and rotated
- Drawings are stored as a digitised file in a computer instead of on paper
- The drawing can be used to automatically produce a bill of materials
- Easy redesigns and corrections
- Files can be shared through electronic media such as e-mail, and easily shared
Possibly most importantly from a manufacturing standpoint, CAD programmes can be linked to other computer programmes used in the manufacturing process.
A CAD file in its simplest form uses the established method of placing co-ordinates – that is to say the dimension from left to right being known as X, and the dimension from top to bottom being Y. The point where we start is known as the origin, or 0,0 in CAD terms.
So, the translation of possibly the simplest form of drawings – let’s say that of a straight horizontal line 99mm long becomes, in CAD terms, a feature with a beginning at point 0,0 and an end at point 0,99. This principle underlies every aspect of even the most complex CAD creation.