Quality Control (AQA GCSE Design & Technology): Revision Note
Exam code: 8552
What is quality control?
Quality control (referred to as QC) is the checking of materials, components, processes and finished products against an agreed standard
Checks may happen before, during and after manufacture
Input checks confirm that materials and components are correct before production
In-process checks identify errors early, reducing the number of faulty products
Final inspection confirms appearance, dimensions, function and safety
Sampling checks selected products; 100% inspection checks every product
A quality standard may be a drawing, tolerance, approved sample, go/no-go fixture or digital test result
Examiner Tips and Tricks
Don't confuse quality control with quality assurance in your answers.
Quality assurance (QA) is the planning done before manufacture starts, such as staff training, choosing reliable suppliers and writing procedures, to prevent faults happening in the first place.
Quality control (QC) is what this page covers: the physical, measurable checks, such as registration marks, a go/no-go fixture or a depth stop, carried out during and after manufacture to check a product meets the required standard
Paper and board products
Registration marks are small printed marks outside the finished design
These show whether separate colours, print layers and cutting operations are aligned
Check that all marks overlap accurately before trimming or die cutting
Misalignment can create blurred colour edges or cuts that do not match the graphics
Worked Example
Explain how registration marks as a quality-control method reduce waste.
[2 marks]
Answer
It identifies an incorrect setting or faulty component before many more products are made, [1] allowing the process to be corrected and reducing rejected products and wasted material. [1]
Examiner Tips and Tricks
For questions about quality control, try to answer the question in the context of either
A school workshop
A factory scale manufacturer
A small production maker
This will help you to focus your response and expand your answer to potentially achieve more marks.
Timber based products
Dimensional accuracy is checked using a go/no-go fixture
A go/no-go fixture quickly checks whether a component lies within the permitted size range
The component must fit the GO opening or position but must not pass the NO-GO limit
This is faster and more consistent than measuring every part numerically
Metal based products
Dimensional accuracy using a depth stop
A depth stop limits how far a drill, milling cutter or other tool can travel
Set the stop using a rule, gauge or trial piece, then check the first component before producing the batch
Worked Example
Explain how a depth stop quality-control method reduces waste.
[3 marks]
Answer
It identifies an incorrect setting or faulty component before many more products are made, [1] allowing the process to be corrected [1] and reducing rejected products and wasted material. [1]
Polymer products
Dimensional accuracy by selecting correct laser settings
Laser power, speed and focus affect the width of cut, edge quality and final dimensions
Use a test piece to select settings for the polymer and thickness
Too much power can melt a wide kerf; too little may not cut through
Textile based products
Checking a repeating print against an original sample
An approved sample acts as the quality standard for pattern size, colour and repeat spacing
Lay the new print beside or over the sample and check alignment at repeated intervals to detect drift
Electrical and mechanical products and systems
UV exposure, developing and etching times in PCB manufacture
Photosensitive PCB production depends on controlled times at each stage
Underexposure may leave a weak image
Overexposure may damage fine tracks Incorrect developing or etching can leave unwanted copper or remove required tracks
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