Computer 3D modeling is causing revolutionary change in mechanical design processes.

Totally New Concepts
Conventional 2D drafting used the language of drawing to express design details. Computer Aided Drafting (CAD) using an electronic drawing board was much more efficient in making drawings, but still used various lines to convey the design information. In 3D modelling on the other hand, instead of making drawings, the designer starts by "modeling" parts and assemblies in a flexible virtual environment - drawings are a by-product. Computer prototyping work is carried out from the beginning thus shortening the design process. Mechanisms can be checked by moving related parts; interference between components can be readily identified.

Design environment
Today's 3D modeling packages are usually coupled with specific design environments. One example is sheet metal work where making development views is only a matter of clicking a button. Features like bending radius and relief notches can be easily set. Stress analysis is another example. By applying forces onto your models the stress level can be shown by color coding or in numbers. With a few button clicks the weak link of the design or excessive material can be clearly identified. 

Flexibility
Another major advantage of 3D modeling is its flexibility. Unlike physical mockups, computer 3D models are totally flexible - it is very easy to add, delete or change details of components and set relationships between components (using "mates" and equations). These changes can be made without losing the original design by defining different variations of the design, called "configurations". A 3D model can have many configurations. Configurations can be controlled by a set of predefined data in a spreadsheet or database format (called design tables).

Take an axial fan for example. A model is created without regard for specific dimensions of the fan. Design rules and criteria are then added to the model. These might include, for example, the relationship between blade size and fan size, and motor mounts being a function of motor size and casing diameter. A design table can be established to contain different variations of the range, such as size of the fan, with or without inlet cone, with or without mounting feet etc. Thus the model is dynamic depending on which configuration we choose. New models of fans could be generated almost instantly by only once assigning data into a new configuration or changing a design rule. This would be in stark contrast to 2D drafting where hundreds of related drawings would need revision.

Accuracy
3D modeling produces higher accuracy in designs because of (1) the nature of "virtual mockup" - errors such as interference are identified easily, and (2) human error is minimized as design variations are automatically updated by the computer.

Development at Air Design
Air Design is currently undertaking the transition from 2D drafting to 3D modeling by implementing the "SolidWorks" software package. The above axial fan example is used only for clarity; the real motivation for this significant investment comes from our MODUtherm air handling range where there are thousands of combinations of unit sizes, fans, coils, filters etc. and massive design rules apply. It is an ideal situation for 3D modeling where we (the designers) focus on rules and criteria and let the computer take care of the variations.

3D modelling means efficiency and accuracy and hence means better products and services to our customers.