Material Selection Factors
GCSE — 2.1.2 In-depth Knowledge: Product Design
Aesthetics
Aesthetic properties — how a material or component looks, including shape, colour, texture, form, reflection, gloss and style.
| Material | Aesthetic properties |
|---|---|
| Aluminium | Good reflector of light, silver appearance |
| Copper | Wide chromatic appeal — red, brown, gold, silver, green (oxidised) |
| Brass | Bright gold appearance, hints of silver-white and red-brown |
| Pewter | Like silver, can be polished very shiny, but tarnishes easily |
| Oak | Mid-brown with prominent grain |
| Pine | Soft pale white or yellow with straight grain |
| Papers and boards | Can be printed, embossed, coloured and given gloss or matt finishes |
Function
Functional properties — how a material or component works for its intended use, including performance, efficiency, reliability and operation.
| Material | Functional properties |
|---|---|
| Aluminium | Very light, strong at low temperatures, corrosion resistant, excellent conductor of heat and electricity, non-toxic, non-sparking |
| Copper | Corrosion resistant, highly malleable, durable, ductile, excellent conductor |
| Brass | Corrosion resistant, harder than copper, malleable, ductile, conducts heat and electricity, can be scratched |
| Mild steel | High tensile and impact strength, good ductility, magnetic, malleable — but corrodes easily and requires finishing |
| Pewter | Soft alloy, very low melting point, perfect for casting |
| Plywood | Strong and rigid — layers at 90° increase strength; edges can look unsightly |
| MDF | Cheap, no grain, versatile — requires a finish |
| Papers and boards | Lightweight, cheap, easily cut, folded, creased and glued; can be waxed or laminated for water resistance; highly recyclable |
Other factors influencing material selection
- Availability — is the material easy to get in the stock form and size needed? Rare materials cause delays and increase cost.
- Cost — the material must suit the product’s price point and scale of production.
- Social — is the product safe and suitable for everyone who will use it? Will it affect people around them?
- Cultural — are the material, colour or symbols acceptable to the target market? Some may cause offence in certain cultures.
- Ethical — was the material sourced and processed fairly, without exploiting workers or damaging communities?
- Environmental — is the material renewable, recycled or recyclable? What is its carbon footprint?
Materials and the environment
Designers and manufacturers have a moral, ethical and sometimes legal responsibility when selecting materials:
- Use responsibly sourced or sustainable materials
- Efficient production methods
- Lower carbon emissions and pollution
- Modern thinking is ‘cradle to cradle’ — no products should be disposed of entirely; they should be disassembled, reused or recycled where possible
Biodiversity and deforestation
- Avoid damage to natural habitats — source materials sustainably
- The Six Rs help guide sustainable choices
- FSC (Forest Stewardship Council) and managed forests supply sustainable timbers
- Select recycled materials over virgin materials
- Protect wildlife and natural ecosystems
Global manufacture
- Parts of products are made in different locations around the world
- Benefits: cheaper labour, investing in poorer countries’ economies
- Risks: child exploitation, unfair working conditions
- Fair Trade tries to ensure everyone benefits fairly
Low labour costs in some countries can mean poverty wages, long hours and exploitation of employees. Designers and manufacturers have a responsibility to check working conditions in their supply chains.
Cost of a prototype
Making a prototype involves more costs than just materials:
- Energy costs to power machinery
- Labour costs — prototypes are often one-off, hand-made items
- CAD/CAM CNC costs — very expensive equipment
- Intellectual property costs to protect the invention
New and developing materials
New materials are constantly being developed. For example:
- 3D printing PLA (polylactic acid) — inexpensive, made from plant starch (e.g. corn or sugar cane) rather than oil, and compostable in industrial composting facilities. It is printed at around 190–220°C and is available in many colours and finishes.
- New biodegradable and compostable polymers are being developed as alternatives to oil-based plastics