Computer-aided design (CAD) is used in prototyping to create, visualize, test, and modify a design digitally before or alongside making physical prototypes. It enables faster iteration, improves accuracy, and can generate files for computer-aided manufacture.
In A2.2 Prototyping techniques, a CAD model can function as a virtual prototype. Designers use it to evaluate form, dimensions, assembly, movement, and sometimes material performance without producing a new physical model after every change.
| CAD use | Contribution to prototyping | Example |
|---|---|---|
| 3D modelling and rendering | Communicates a product's form, proportions, colour, and surface finish | Comparing alternative casing designs |
| Dimensional and assembly checking | Identifies incorrect sizes, interference, or poor component fit | Checking whether gears collide inside a mechanism |
| Digital simulation | Predicts factors such as stress, deformation, motion, or airflow | Locating areas of high stress in a chair frame |
| Manufacturing-file generation | Transfers accurate geometry to rapid-prototyping equipment | Sending a model to a 3D printer or CNC machine |
Parametric modelling makes iteration especially efficient. When a dimension or constraint is changed, connected features can update automatically, allowing designers to develop and compare alternatives quickly while maintaining consistency.
CAD also supports computer-aided manufacture (CAM). For example, a CAD model may be exported for additive manufacturing, laser cutting, or CNC machining to produce an accurate physical prototype. This reduces transcription errors between the design and manufacturing stages.
A common misconception is that CAD replaces all physical prototypes. Digital models and simulations depend on assumptions and may not accurately reproduce ergonomics, tactile qualities, material defects, or real user interaction, so physical testing is often still necessary.