Designing for the user and for manufacture
Design & Technology · GCSE · The School
Fitting the body
ANTHROPOMETRIC data is measurements of human bodies — hand span, sitting height, reach. ERGONOMICS is designing so a product fits the person using it. Designers work to a PERCENTILE RANGE, commonly the 5th to 95th, because designing for an average fits almost nobody exactly and excludes the extremes entirely.
Design for manufacture
A product that can be drawn is not necessarily a product that can be MADE at a sensible cost. Fewer parts, standard components, tolerances that are achievable, shapes a mould can release, and joins a machine can reach — all of these decide whether a design can be produced or only prototyped.
The trade-off
User needs and manufacturing costs pull against each other constantly. A shape that fits the hand perfectly may need an expensive mould. The designer's job is not to pretend there is no conflict but to decide it explicitly and be able to justify the decision — which is exactly what an examiner is looking for.
Handle height: set it for the 5th percentile reach, so short users can reach it — taller users can always reach lower. Grip diameter: set for the 50th percentile hand, since both extremes must manage it. Door width: set for the 95th percentile shoulder, so broad users fit — narrower users are unaffected. Three dimensions, three different percentiles, each chosen by asking which end of the range would be excluded.