What is computer-aided design (CAD), and what are its advantages and disadvantages?
Computer-aided design (CAD): what it is, its use in engineering, and its advantages and disadvantages.
A CCEA GCSE Engineering and Manufacturing answer on computer-aided design (CAD), how engineers use it to create and modify designs, and its advantages and disadvantages compared with manual drawing.
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What this dot point is asking
CCEA expects you to know what computer-aided design (CAD) is, how engineers use it, and to give balanced advantages and disadvantages. CAD has largely replaced drawing by hand and links directly to manufacture.
The answer
What CAD is
Advantages of CAD
Disadvantages of CAD
- High cost of software, powerful hardware and ongoing licences.
- Training is needed; the software is complex.
- Reliance on the system: crashes, power cuts or viruses can lose work.
- Security: design files can be copied or stolen, so they must be protected.
Worked example: justifying CAD
Examples in context
- Example 1. Designing a phone case
- The designer models it in CAD, tests that the buttons line up and the case fits, then sends the file to a CNC machine or 3D printer, with no hand drawing.
- Example 2. Modifying a part
- A customer wants the part 5 mm longer; in CAD this is changed in seconds and the new drawing and CAM file are produced automatically, where a hand drawing would be redrawn from scratch.
- Example 3. Client approval
- A photorealistic CAD render shows the client the finished product before manufacture, so changes are agreed early and cheaply.
The pattern is that CAD speeds up design, improves accuracy and connects straight to manufacture, at the price of cost, training and dependence on the computer system.
Try this
Q1. What is CAD? [1 mark]
- Cue. The use of computer software to create, modify and store engineering designs and drawings (2D and 3D).
Q2. Give two advantages of CAD over drawing by hand. [2 marks]
- Cue. Fast editing without redrawing, exact dimensions, easy sharing/storage, on-screen testing, or links to CAM.
Q3. Give one disadvantage of using CAD. [1 mark]
- Cue. High cost of software/hardware, training needed, or reliance on the system (crashes can lose work).
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA style4 marksGive two advantages and two disadvantages of using CAD to design an engineered product.Show worked answer →
Two advantages:
- Designs can be changed and edited quickly without redrawing from scratch, and stored, copied and shared electronically.
- The 3D model can be tested and simulated (for stress, fit or motion) before anything is made, and accurate dimensions reduce errors.
Two disadvantages:
- High cost of the software, powerful computers and training.
- Reliance on the system: a power cut, crash or virus can lose work, and staff must be skilled to use it.
Markers reward two valid advantages (speed of editing, sharing, accuracy, simulation, photorealistic views, links to CAM) and two valid disadvantages (cost, training, reliance on hardware/software, security).
CCEA style3 marksExplain how CAD helps reduce the number of physical prototypes a company needs to make.Show worked answer →
With CAD, the design exists as an accurate 3D model on screen, so engineers can test and simulate it (for example checking that parts fit, that a structure is strong enough, or that a mechanism moves) before making anything.
Faults can be found and corrected on the model, so fewer physical prototypes are needed to get the design right, which saves time and material cost.
Markers reward the idea that virtual testing/simulation on the CAD model finds faults early, so fewer real prototypes are built, saving time and money.
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