Quality control and quality assurance

Two complementary ideas keep quality high:

• Quality control (QC) — inspecting and testing products (or samples) to catch defects after they occur.
• Quality assurance (QA) — building quality into the whole process so defects are prevented, often certified to ISO 9001.
• The BSI Kitemark shows independently verified compliance with a standard.

QC or QA?

Tolerances and testing

Parts are made to a permitted range:

• Nominal size — the target dimension.
• Upper and lower limits — largest and smallest acceptable sizes.
• Tolerance = upper limit - lower limit.

Solutions are also judged by testing against the specification and by user feedback.

Your turn — tolerance

Marketing and the product life cycle

A product must be commercially viable:

• Product life cycle — introduction, growth, maturity and decline; marketing and redesign can extend it.
• Niche market — a small, specialised group; mass market — a large, general audience.
• Branding and the marketing mix position a product against competitors.

Niche or mass?

Costing, enterprise and feasibility

Viability rests on the numbers:

• Fixed costs (tooling, rent) do not change with output; variable costs (materials, labour per unit) do.
• Break-even quantity = fixed costs ÷ (selling price - variable cost). Below it the product makes a loss.
• Profit margin and market size decide whether a solution is worth producing.

Your turn — break-even

Sort the viability factors

Tap a factor, then the group it belongs to.

Match each term to its meaning

Tap an item on the left, then its match on the right.

The big ideas to know

You have covered how quality, marketing and cost decide whether a design is viable.