Computer-Aided Design (CAD)

This lesson explores the role of Computer-Aided Design (CAD) in the design and manufacturing process. CAD is a key topic in AQA GCSE Design and Technology (8552), Section 3.1.1, and understanding its tools, benefits and limitations is essential for both the written exam and your NEA project.

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What Is CAD?

Computer-Aided Design (CAD) is the use of computer software to create, modify, analyse and optimise designs. CAD has largely replaced traditional drawing-board methods in professional design and engineering.

Types of CAD Software

Software Type	Description	Examples
2D CAD	Creates flat, technical drawings (plans, elevations, sections)	AutoCAD, LibreCAD
3D solid modelling	Creates solid 3D models that can be sectioned and analysed	SolidWorks, Fusion 360, Onshape
3D surface modelling	Creates complex curved surfaces (e.g. car bodies)	Rhino, Alias
Parametric modelling	Dimensions drive the model — changing one value updates the whole design	SolidWorks, Inventor, Fusion 360
Free-form / sculpting	Organic shapes modelled like digital clay	ZBrush, Blender
PCB design	Designing printed circuit board layouts	EAGLE, KiCad

Common CAD Tools and Features

Tool / Feature	Function
Extrude	Extends a 2D sketch into a 3D solid
Revolve	Rotates a 2D profile around an axis to create a symmetrical 3D shape
Fillet / chamfer	Adds rounded or angled edges to a model
Boolean operations	Combines, subtracts or intersects solid shapes
Assembly	Brings multiple parts together to check fit and movement
Section view	Cuts through a model to reveal internal details
Rendering	Applies materials, lighting and textures to produce photorealistic images
Simulation / FEA	Tests stress, strain and thermal performance digitally before making a prototype
Nesting	Arranges parts on a sheet to minimise material waste

AQA Exam Tip: If asked to describe the advantages of CAD, go beyond just "it's faster." Mention specific features like rendering, simulation, nesting and parametric editing — this shows deeper knowledge and targets the higher mark bands.

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Advantages of CAD

Advantage	Explanation
Speed	Designs can be created and modified much faster than by hand
Accuracy	Dimensions are precise to fractions of a millimetre
Easy modification	Changes can be made without starting from scratch
Visualisation	Photorealistic renders help clients understand the product before it is made
Simulation	Stress analysis (FEA) and movement simulation reduce the need for physical prototypes
Collaboration	Files can be shared instantly with team members anywhere in the world
Data transfer	CAD files can be sent directly to CNC machines, 3D printers and laser cutters
Material estimation	Software calculates mass, volume and cost of materials
Version control	Previous versions of a design are saved and can be restored

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Disadvantages of CAD