Product, Process, and Service Design
What to master
The design domain is about control of the translation from customer need to a producible, reliable design. Know the flow: design inputs (customer, regulatory, and internal requirements) → design outputs (drawings, specs, software) → design review → verification → validation → design transfer → control of design changes, with configuration management throughout.
The classic trap: verification answers did we build it right (does the output meet the input requirements - tests, analyses, inspections); validation answers did we build the right thing (does it satisfy the user's needs in actual use - clinical trials, field trials, beta use). A design review is neither; it is a planned, documented, cross-functional evaluation of design adequacy.
Other must-knows: QFD house of quality linking voice of the customer to technical requirements through a relationship matrix; DFMEA and its link to design controls; Taguchi robust design (orthogonal arrays, signal-to-noise ratios, parameter design to reduce sensitivity to noise); DOE for characterizing factor effects; tolerance stack-up analysis; APQP phases and PPAP submission; design for manufacturability, assembly, and serviceability; concurrent engineering; and reliability fundamentals - the bathtub curve (infant mortality, useful life, wear-out) and MTBF = 1/λ for a constant failure rate.
Worked example. In a house of quality, customer need A has importance 5, need B has importance 4. A technical requirement scores 9 against A and 3 against B. Absolute importance = (5 × 9) + (4 × 3) = 57. Repeat for each technical requirement and rank; the highest scores become the design priorities.