What categories of material are used in products, and what physical and mechanical properties decide which is suitable?
The main categories of material (timbers, metals, polymers/plastics) and the physical and mechanical properties that decide suitability: strength, hardness, toughness, durability, elasticity, plasticity, malleability, ductility, density, conductivity and corrosion resistance.
A focused answer to the SQA National 5 Design and Manufacture content on materials and properties, covering the categories of material (timbers, metals, plastics) and the physical and mechanical properties - strength, hardness, toughness, malleability, ductility and more - that decide which material suits a product.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
The SQA wants you to know the main categories of material and the properties that decide whether a material suits a product. The skill tested most often is matching a property to a need: explaining why a particular property matters for a given product, and choosing a suitable material because of its properties.
The main categories of material
The next dot point looks at specific named materials and their uses; this one is about the properties that make any material suitable.
Mechanical properties
Mechanical properties describe how a material behaves when a force is applied.
- Strength: the ability to resist a load without breaking. A shelf needs strength to bear weight.
- Hardness: the ability to resist scratching, denting and wear on the surface. A worktop needs hardness.
- Toughness: the ability to absorb sudden shocks or blows without cracking. A hammer head must be tough.
- Elasticity: the ability to bend or stretch and return to the original shape. A spring is elastic.
- Plasticity: the ability to be permanently shaped and keep the new shape (the opposite of elastic).
- Malleability: the ability to be hammered, pressed or rolled into shape without breaking (e.g. forming sheet metal).
- Ductility: the ability to be drawn out into a thin wire without breaking (e.g. copper into cable).
Physical properties
Physical properties describe the material itself, not its response to force.
- Density: mass for a given volume. Low-density materials (aluminium, many plastics) are light; high-density materials are heavy.
- Electrical conductivity: how well it carries electricity. Metals (copper) conduct; most plastics are insulators.
- Thermal conductivity: how well it carries heat. Metals conduct heat; plastics and timber insulate.
- Durability: how well it lasts in use and resists wear and weathering.
- Corrosion/weather resistance: how well it resists rusting or rotting. Non-ferrous metals and treated timbers resist the weather; ferrous metals rust unless protected.
Matching properties to a product
Try this
Q1. State what is meant by the toughness of a material. [1 mark]
- Cue. The ability to absorb sudden shocks or blows without breaking or cracking.
Q2. Name two material properties important for a kitchen worktop and say why. [2 marks]
- Cue. Hardness (resists scratches and wear); durability or water resistance (lasts and is not damaged by spills).
Q3. Explain why copper is used for electrical wiring. [2 marks]
- Cue. It is an excellent electrical conductor and is ductile, so it can be drawn into thin wire that carries current well.
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA-style Explain4 marksA garden bench is to be made for outdoor use. Explain why two named material properties are important for this product.Show worked answer →
Award up to 2 marks for each property explained as a cause and effect, to a maximum of 4. Durability and corrosion/weather resistance: the bench is left outdoors, so the material must resist rain, sun and rot, otherwise it would rust or decay and fail quickly; a weather-resistant timber or treated metal lasts much longer (2). Strength and toughness: the bench must support the weight of people sitting on it without bending or cracking, so a strong, tough material is needed to take the load and resist knocks (2). Other creditable properties include hardness (resisting scratches) and density (keeping the bench heavy enough to be stable but not impossible to move). Markers reward the link between the property and the demand of the product.
SQA-style Describe3 marksDescribe the difference between the properties hardness, toughness and malleability.Show worked answer →
Award 1 mark per property correctly described, up to 3. Hardness is the ability of a material to resist scratching, denting and wear on its surface (1). Toughness is the ability to absorb sudden shocks or blows without breaking or cracking (1). Malleability is the ability to be hammered, pressed or rolled into a new shape without breaking (1). A common mistake is to confuse toughness with strength, so a clear, distinct description of each property is needed. Markers reward three separate, correct descriptions rather than overlapping ones.
Related dot points
- Named materials and their uses: natural timbers (hardwoods and softwoods) and manufactured boards (MDF, plywood, chipboard), ferrous and non-ferrous metals (mild steel, aluminium, copper, brass), and thermoplastics and thermosetting plastics (acrylic, polypropylene, ABS, polythene, urea formaldehyde).
A focused answer to the SQA National 5 Design and Manufacture content on named materials, covering natural timbers and manufactured boards, ferrous and non-ferrous metals, and thermoplastics and thermosetting plastics, with typical product uses for each.
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A focused answer to the SQA National 5 Design and Manufacture content on manufacturing processes, covering marking out, cutting and wasting, shaping and forming such as vacuum forming and line bending, fabrication and joining methods, and surface finishing and why products are finished.
- Commercial manufacture: the scales of production (one-off/job, batch and mass/continuous production), their effects on cost and quantity, and the use of jigs, templates, moulds, computer-aided manufacture (CAM) and automation to ensure consistency and speed in industry.
A focused answer to the SQA National 5 Design and Manufacture content on commercial manufacture, covering one-off, batch and mass production, how scale affects cost and quantity, and the use of jigs, templates, moulds, CAM and automation for consistency in industry.
- Sustainability and the product life cycle: the stages of a product's life (raw materials, manufacture, distribution, use, disposal/re-use), the environmental impact at each stage, and reducing impact through the 6 Rs (reduce, reuse, recycle, refuse, rethink, repair).
A focused answer to the SQA National 5 Design and Manufacture content on sustainability, covering the stages of a product's life cycle from raw materials to disposal, the environmental impact at each stage, and reducing impact through the 6 Rs.