Tools, Equipment & Processes — Finishing (AQA GCSE Design & Technology): Revision Note
Exam code: 8552
3D printing
3D printing is an additive manufacturing process that builds a component layer by layer from digital data
How 3D printing works
FDM printers melt and extrude polymer filament such as PLA or ABS
The CAD model is sliced into thin layers before printing
Supports may be added beneath overhangs and removed after printing
It is well suited to one-off prototypes and complex internal forms
Typical products and prototypes
Concept models, casings, clips, gears and customised components
Waste and quality
It creates less waste than subtractive machining, although support material, failed prints and purge material may be discarded
Worked Example
Why is 3D printing useful for developing a prototype part that fits into a hand?
[4 marks]
Answer
A CAD design can be changed and reprinted quickly [1] without making expensive tooling. [1] Complex shapes like those designed to fit the hand often need iteration, [1] and 3D printing can be used to produce parts as a one-off model. [1]
Examiner Tips and Tricks
For material acronyms, using the acronym is equally as valid as stating the full name of a material. For example you will still receive the marks for stating an answer as PLA, vs stating the full name of Poly Lactic Acid.
Batik
Batik is a dyeing process in which wax applied to a fabric blocks dye from selected areas of a textile
How batik works
A design is drawn onto natural fabric, commonly cotton
Hot wax is applied using a tjanting tool, brush or stamp
The fabric is dyed; waxed areas resist the dye
The process can be repeated with more wax and colours before the wax is removed
Typical products and prototypes
Decorative textiles, wall hangings, clothing panels and prototype surface designs
Waste and quality
Small amounts of wax and dye may be left over; careful planning reduces excess materials and prevents accidental staining
Worked Example
Explain why wax is used during batik.
[2 marks]
Answer
Wax forms a barrier that prevents dye reaching selected fibres, [1] leaving those areas the original colour or an earlier dyed colour. [1]
Examiner Tips and Tricks
If a question awards two marks for an answer, aim to achieve both of those marks by ensuring your sentence talks about the what and why of your point, and include the “two sides” of your point within each part of your sentence.
For example
Part 1: Wax forms a barrier that prevents dye reaching selected fibres (what part of point is underlined)
Part 2: Protecting the original colour or an earlier dyed colour whilst allowing unwaxed fibres to be dyed (why part of point is underlined)
Printing (manufacturing process)
Printing transfers text, images or patterns onto a material surface using ink
How printing works
Methods include screen printing, block printing, digital printing, lithography, sublimation and pad printing
The method depends on material, quantity, colour accuracy and surface shape
Registration marks align multiple colours
A test print checks scale, colour and position before the final run
Typical products and prototypes
Packaging, textiles, labels, control panels and promotional products
Waste and quality
Set-up sheets, ink, screens and misprints can create waste; proofing and accurate registration reduce rejects
Worked Example
Explain why a test print should be produced before printing a final batch?
[2 marks]
Answer
It allows the designer to check colour, size, position and alignment, [1] preventing a whole batch from being printed incorrectly. [1]
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