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Computer-Aided Design (CAD) is More Than a Drawing Package

• CAD is a software program that very precisely, mathematically defines three dimensional (3D) objects

• CAD software allows objects to be viewed from any direction

• CAD software allows models to be assigned properties such as color, weight, and parametric relationships

• CAD software can describe not just individual parts but also assemblies of parts to ensure parts mate properly

• CAD software generates instructions for engineering drawings and Computerized Numerically Controlled (CNC) manufacturing 


A Brief History of Computer-Aided Design (CAD) 

Prior to the 1950s, designers of physical objects (from buildings to toys) sketched their ideas on a piece of paper. On this same piece of paper, annotations were added giving dimensions, materials to be used, assembly instructions, etc. As designers became more creative, objects became increasingly complex and a group of professional draftsmen was hired to produce drawings that were highly legible and used standardized terminology. While a good designer thought in three dimensions (3D), almost all drawings produced by draftsmen were two-dimensional (2D) at the time. The 2D drawings were given to the second group of professionals to build what the designer had envisioned. Being a very manual process, mistakes were inevitable and very expensive to correct.


The task of drawing objects for the purpose of manufacturing changed significantly with the advent of computers. Programmers developed software that captured information provided by the engineer and displayed it in graphical form. This software introduced a level of accuracy which was difficult to obtain earlier when designers relied on hand calculations.  Computers were also able to generate exceptionally clear, standardized drawings which eased manufacturing. Other features such as automatic scaling made illustrating anything from the size of a ten story building to the gear inside a watch a straightforward task. 

Initially, CAD software was capable of only generating two-dimensional drawings. But when programmers teamed up with mathematicians, the software was improved and it became possible to capture three-dimensional objects. This process has become known as solid modeling. 

As CAD software matured, the use of computers to control the use of machines that manufactured parts also progressed; a process known as Computerized Numerical Control or CNC manufacturing. It was inevitable that the CAD and CNC processes were joined so that parts could be almost seamlessly designed and fabricated. This has resulted in increased accuracy, greatly reduced production time, and decreased cost. Perhaps equally important, when changes are required, as is often the case, a new part can be generated with minimum difficulty. 

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