Prepare a CAD model for rapid prototyping by validating its geometry, adapting it to the chosen manufacturing process, exporting it in a compatible file format, and configuring the machine instructions. The aim is to convert an accurate digital model into a manufacturable physical prototype.
In B2.2 Modelling and prototyping, computer-aided design supports the development, testing, and communication of design ideas. The preparation process should include these stages:
| Stage | What must be checked |
|---|---|
| Validate geometry | Ensure the model is a closed, watertight solid without holes, overlapping surfaces, duplicated features, or non-manifold edges. |
| Confirm dimensions | Check units, scale, critical dimensions, and the maximum build volume of the rapid-prototyping machine. |
| Apply tolerances | Add suitable clearance between mating or moving parts and account for the machine's accuracy and material behaviour. |
| Adapt features | Check minimum wall thickness, small details, unsupported sections, and fragile features against process limitations. |
| Select orientation | Orient the model to reduce support material, production time, material waste, and poor surface finish. |
| Export the file | Convert the CAD model into a compatible format, commonly STL or 3MF, using sufficient mesh resolution to represent curved surfaces accurately. |
| Slice and verify | Use slicing software to generate layers and machine instructions. Inspect the preview for missing layers, supports, and unexpected voids. |
The exact preparation depends on the process. Additive manufacturing may require support structures, layer-height selection, and infill settings. Subtractive rapid prototyping requires consideration of tool access, workholding, and whether the cutting tool can produce internal features.
A common misconception is that a CAD file can be sent directly to any rapid-prototyping machine. It normally requires process-specific conversion and verification before manufacture.
In an IB response, explain the preparation as a sequence and justify decisions using criteria such as accuracy, material use, production time, surface finish, and prototype purpose. For an “explain” question, link each action to its effect rather than merely listing steps.