C · 语境中的设计

What would explain this observation?

• A repairable product may cost more initially but stay in service longer. A design decision needs evidence across manufacture, use and disposal.
• Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.

Build the model

• Design for disassembly 可拆卸设计 supports separation of materials and replacement of parts. Manufacturing choices depend on production volume, tolerances, material properties and cost. Sustainability includes environmental and social effects.
• design for disassembly: Design supporting separation and replacement of parts; tolerance 公差: An allowed dimensional variation.

Choose evidence that can test it

• Compare a common service over a stated lifetime. Separate fixed tooling cost from cost per item. Include repair, energy, transport and realistic end-of-life pathways rather than using a recycled label as the whole judgement.
• Create a bill of materials and an annotated assembly plan. Test whether a worn part can be replaced with normal tools. For HL project development, evaluate production feasibility and commercial assumptions against the applicable cohort guide.

Work from known quantities

• State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
• Known: method A costs 600 fixed units plus 4 per item; method B costs 100 fixed units plus 9 per item. Equality: 600+4n = 100+9n. Rearranging: 500 = 5n, so n = 100 items. Other quality and sustainability criteria may change the choice.

Example:

Fixed costs differ by 400 units and unit costs differ by 5. Find cost break-even quantity. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.

Check the conclusion and its limits

• A cheaper process is not automatically preferable. Cost estimates need currency, quantity and assumptions, and prototypes do not prove mass-production consistency.
• Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.

Warn:

A recycled-content label establishes the entire product life-cycle impact. This claim is false: A cheaper process is not automatically preferable. Cost estimates need currency, quantity and assumptions, and prototypes do not prove mass-production consistency.

Key:

Design sustainability and production choices: Compare a common service over a stated lifetime. Separate fixed tooling cost from cost per item. Include repair, energy, transport and realistic end-of-life pathways rather than using a recycled label as the whole judgement.