OCR A-Level Product Design materials and their properties: a complete overview

What this topic demands

The materials topic is the technical foundation of Component 01. It tests whether you can classify a material, state its properties precisely, calculate its density, recognise smart and modern materials and justify a material choice for a product. Marks are lost when properties are swapped (hardness for toughness) or when a density calculation is left in the wrong units, and gained by tying every material to a named product. This overview ties the four dot-point pages together.

Classifying materials

Materials in product design fall into five families. Papers and boards are sheet materials from wood pulp, classed by weight in grams per square metre, used for packaging, modelling and graphics. Timbers are natural hardwoods (broadleaved, slow-grown, dense, for example oak) and softwoods (coniferous, faster-grown, lighter, for example pine), plus manufactured boards (plywood, MDF, chipboard) that are more stable and come in large sheets. Metals are ferrous (contain iron, magnetic, rust, for example mild steel), non-ferrous (no iron, for example aluminium and copper) and alloys (mixtures engineered for better properties, for example brass and stainless steel). Polymers are thermoplastics (weak intermolecular bonds, reshape and recycle) and thermosets (covalent cross-links, set permanently). Composites combine a matrix and a reinforcement (GRP, CFRP, reinforced concrete) for a high strength-to-weight ratio. See classification of materials.

Physical and mechanical properties

Properties link a material's structure to its job. Strength resists a force (tensile to pulling, compressive to squashing); hardness resists scratching and wear; toughness absorbs energy and resists impact; the two often trade off, because hard materials are often brittle. Ductility is drawing into a wire; malleability is hammering into sheet; elasticity is springing back; plasticity is keeping a new shape. Density is mass per unit volume, $\rho = \frac{m}{V}$, in kilograms per cubic metre, and is the property Component 01 most often asks you to calculate. Conductivity and durability complete the set. See properties of materials.

Smart and modern materials

A smart material changes a property in response to a stimulus: shape memory alloys (heat restores shape), thermochromic pigments (heat changes colour), photochromic pigments (light darkens them), piezoelectric materials (deform and generate a voltage) and electroluminescent materials (emit light in an electric field). A modern material is an advanced research material defined by an outstanding property: Kevlar (strength-to-weight), graphene (strength and conductivity), nanomaterials (coatings and sensors) and polymorph (a hand-mouldable thermoplastic). See smart and modern materials.

Selecting materials and stock forms

A material choice balances function, aesthetics, cost, manufacture, availability and environment, and is bought in a standard stock form: sheet, bar, rod, tube, extrusion, section, granules, powder, wire or board. Choosing a stock form close to the final shape cuts both machining and waste. A good answer names the material and stock form, links each to a product demand and justifies the compromise. See selecting materials and stock forms.

How to revise this topic

1. Learn the categories with examples. A named material and product for each family is a recall mark you cannot afford to drop.
2. Get the properties exact. Do not swap hardness and toughness, or ductility and malleability; define each in your own words.
3. Drill the density calculation. Convert lengths to metres, then use $\rho = \frac{m}{V}$, and keep the units.
4. Link smart materials to a stimulus. A smart material is defined by what it responds to, so always name the trigger.
5. Practise selection evaluations. Weigh several factors on a real product and reach a justified decision, then attempt the quiz.