Question 10 of 10: Stages of the Design Process

Question 10: Stages of the Design Process (10 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

The engineering design process moves from an abstract need through to fully documented, manufacturable drawings, iterating and validating at each stage.

1. Identify the need / problem statement. A need for a small, hand-releasable fastening device is recognized (e.g., to latch a lid or gate closed) — stated in terms of function, not a specific shape.
2. Define design requirements / specifications. Constraints are set: the latch must pivot open/closed about a pin, engage a loop/hook feature, fit within an envelope, and be producible from sheet or bar stock — translating the need into measurable criteria.
3. Conceptual design (ideation). Several candidate mechanisms are sketched freehand (hook-and-eye, sliding bolt, spring clip); for the hinge shown, a two-plate-plus-pin hook concept is selected as simplest to fabricate and operate.
4. Preliminary design and analysis. The chosen concept (Bottom Latch, Top Latch, Latch Pin) is proportioned: the Bottom Latch's hook/loop and mounting holes, the Top Latch's slot (which lets the pin's travel accommodate mis-alignment), and the pin's diameter/length are checked against the load and clearance requirements.
5. Detail design. Each of the three parts is fully dimensioned and toleranced (hole sizes for the mounting screws, the pin's running fit in the Bottom Latch's barrel, material and finish callouts) — the stage that produces the individual part drawings.
6. Prototyping and testing. A physical hinge assembly is built and cycled to confirm the Latch Pin seats and releases smoothly and the slotted Top Latch clears the hook through its full range of motion.
7. Production / assembly and working drawings. The final assembly drawing (the exploded view shown, with its item-number/title/quantity parts list: 1 Bottom Latch, 2 Top Latch, 3 Latch Pin) plus the three detail drawings are released for manufacture.
8. Review and iteration. Feedback from testing or production is fed back into earlier stages (e.g., if the pin were found to bind, its clearance would be revisited in detail design) — the process is cyclical, not strictly linear.