Design and Applied Technology Advanced: Application and Exam Skills
FoundationThis lesson deepens manufacturing knowledge — cutting, forming, joining and surface treatment, plus prototype versus mass production — and builds exam skills for comparison questions and system-based scenario questions.
- Four process families each play their part: cutting sets shape, forming shapes the body, joining assembles, surface treatment finishes.
- Match processes to material character and production quantity: prototypes prize speed, production prizes consistency and economy.
- Validate by prototype first, then tool up — the right order for controlling risk and cost.
文體小知識：科技知識說明文——介紹切割、成型、接合與表面處理等加工工藝及批量生產概念，並示範比較題與系統情境題的作答策略。
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1Ideas become real through processes. Manufacturing processes fall into four broad kinds: cutting divides material into the shapes needed, such as sawing, shearing and laser cutting; forming shapes material into solids, such as bending, injection moulding and vacuum forming; joining assembles parts into a whole, such as gluing, nailing, screwing and welding; surface treatment improves appearance and durability, such as sanding, spray painting and electroplating. The four kinds alternate as the design cycle advances.
2Choosing a process depends on the material's character and the production quantity. Wood suits sawing and sanding, metal can be welded and bent, and plastics can be vacuum-formed or injection-moulded when heated. Prototypes prize fast modification, so hand tools and 3D printing dominate; mass production needs moulds — an injection mould forms one identical piece after another, unit cost falling as quantity rises, but the mould itself is expensive, so the design should be proven by prototypes first.
3Quality and safety run through every process. Cutting should leave allowance for finishing; joints must respect the direction of forces; welds must be checked for weakness. Sanding away sharp edges protects users from cuts, while surface treatment wards off rust and moisture and makes products attractive. On drawings, designers mark dimensions and tolerances so producers know which positions must be exact and which may be relaxed.
4The first advanced exam skill is answering comparison questions: establish points of comparison such as cost, strength, durability, weight and workmanship, then weigh the two options point by point, and finish with a short verdict. Never praise one side only, or vaguely claim that both have merits without comparison points. Thinking in table form keeps the answer orderly and shows the marker your analytical power at a glance.
5The second skill is answering scenario system questions: while reading, underline the requirements — the users, the setting, the functions; then decompose the product into input, processing and output and judge whether it is open-loop or closed-loop; then present your scheme along the design cycle, from specification to testing, matching each stage to the scenario. Answer exactly what is asked: give reasons for why questions and concrete modifications for how-to-improve questions.
1Summary 重點摘要
This lesson deepens manufacturing knowledge — cutting, forming, joining and surface treatment, plus prototype versus mass production — and builds exam skills for comparison questions and system-based scenario questions.
2Vocabulary cards Vocabulary
Shaping material by sawing, shearing or laser cutting.
Processes that shape material into required solid forms, such as injection moulding and vacuum forming.
Processes that assemble parts into a whole, such as gluing, nailing, screwing and welding.
Finishing that improves appearance and durability, such as sanding, spray painting and electroplating.
A mass-production process injecting molten plastic into a mould to cool into shape.
The permitted deviation from a stated dimension, balancing precision against cost.
Shared criteria for weighing options, such as cost, strength and weight.
Testing a design with a quick prototype to avoid the risk of tooling straight away.
A question type set in a real situation, requiring knowledge to be applied to it.
3Step by step Steps
- Step 1: An overview of the four process familiesManufacturing processes fall into four families by function: cutting removes material to set a shape, such as sawing wood strips or laser-cutting acrylic; forming shapes the body, such as vacuum-forming sheet plastic into a tray; joining assembles parts, such as fixing side panels with screws or welding a steel frame; surface treatment finishes the work, such as sanding and painting. The families alternate throughout the design cycle. For example, making a wooden pencil holder means sawing the board, jointing the corners and waxing the surface in one flowing sequence.
- Step 2: Matching processes to materialsProcesses must suit the material's character: wood saws easily along the grain and takes glued joints; metal bends, welds and turns on a lathe; plastics soften with heat for vacuum forming and injection moulding, while acrylic takes fine laser-cut patterns. A wrong process wastes time at best and ruins the material at worst. For example, drilling a round hole in brittle sheet plastic with an ordinary bit often cracks it; a hole saw or laser cutting leaves a clean, safe edge — a lesson in matching process to material.
- Step 3: Dividing labour between prototype and mass productionThe prototype stage prizes speed and change: hand tools, card and 3D printing let a designer iterate many times within days. The mass-production stage prizes consistency and economy: once a mould is made, processes such as injection moulding and stamping turn out identical pieces with a far lower unit cost, but tooling is expensive and hard to revise. The right order is to validate by prototype before tooling up. For example, a beginner who ordered an injection mould before validating found the button feel poor; the mould was finished, and the cost of change was heavy.
- Step 4: Quality, tolerance and safetyExecuting processes demands quality awareness: leave finishing allowance when cutting so sanding has material to work with; respect force directions when joining, giving glue surfaces enough area and placing screws in solid positions; mark tolerances on drawings so producers know which dimensions must be exact. For safety, deburr sharp edges, round corners and guard moving pinch points. For example, a child's chair must have rounded edges and legs spread wide enough to pass stability tests, preventing toppling and injury.
- Step 5: Point-by-point comparison for exam questionsThe method for comparison questions is to set comparison points first, weigh the options point by point, and end with a verdict. Take the points from the scenario — cost, strength, weight, durability, workmanship; for each point, one sentence on option one and one on option two, with connectives marking which wins or the trade-off; the verdict must answer the question by recommending an option. Take comparing wooden and metal chair frames as an example: compare weight, cost, durability and style point by point, then conclude by the setting of use.
- Step 6: A framework for scenario system questionsScenario questions begin by unpacking the stem: circle the users, the setting and the functional demands; then decompose the product into input, processing and output and judge open-loop or closed-loop; then unfold your scheme along the design cycle from specification to testing, echoing the scenario's keywords in every paragraph. When asked why, give reasons; when asked how to improve, give concrete changes, not empty words. Take a library book-return box as an example: the input is an infrared sensor, the processing decides whether a book was inserted, and the output lights a confirmation lamp — a closed loop that reassures users.
4Diagrams Diagrams
5Worked example Example
Worked example: A project asks each group to build a desk cable tidy, first a prototype and then a plan for mass production. Explain the process choices at the prototype stage and the mass-production stage, and compare their cost considerations.
- Prototype stage: block out the form quickly in card or wood strips, then 3D-print the base — speed and modifiability matter most.
- Mass-production stage: once the form is fixed, open an injection mould; plastic pieces come out identical with even colour, and non-slip pads can be added.
- Cost comparison: the prototype is expensive per piece but cheap overall; the mould is expensive upfront, while unit cost falls as quantity grows.
- Risk control: validate size and feel with the prototype before tooling up, avoiding the heavy cost of modifying a finished mould.
- Answer: Prototypes favour rapid forming and hand tools for speed and change; mass production favours mould processes such as injection moulding for consistency and low unit cost. On cost, the prototype is dear per piece while production is dear at tooling; the larger the batch, the thinner the mould cost spreads. Answer by stages, compare unit cost against total cost, and highlight the risk management of validating before tooling up.
6Common mistakes Mistakes
7Quick check Quick check
Q1What are the four broad families of manufacturing processes?
Q2Why validate with a prototype before mass production?
Q3How does the unit cost of injection moulding relate to quantity?
Q4What is the first step in answering a comparison question?
Q5What should you do first in a scenario system question?
8Recap Recap
- Four process families each play their part: cutting sets shape, forming shapes the body, joining assembles, surface treatment finishes.
- Match processes to material character and production quantity: prototypes prize speed, production prizes consistency and economy.
- Validate by prototype first, then tool up — the right order for controlling risk and cost.
- Comparison questions use shared points, weighed item by item, ending with a scenario-based verdict.
- Scenario system questions start from the scenario's keywords, then organise answers with block diagrams and the design cycle.