Classification of Materials by Source or Origin
- Materials are classified based on their source or origin, such as natural or human-made (synthetic or processed materials).
- This classification affects their properties, environmental impact, and suitability for different products and design applications.
Natural vs. Human-Made Materials
Types of Materials
Timbers
Definition
Timber (lumber)
Timber is wood that has been harvested from trees and processed for use in manufacturing, construction, and carpentry. It is typically classified into softwoods (from coniferous trees) and hardwoods (from deciduous trees), based on the type of tree it comes from.
- A natural material sourced from trees, widely used due to its renewability, strength, and aesthetic qualities.
- Good strength-to-weight ratio.
- Can be machined, sanded, and finished easily.
- Naturally insulating (thermal and acoustic).
- Can be affected by moisture, insects, or rot if untreated
| Type | Hardwoods | Softwoods |
|---|---|---|
| Source | Trees with broad leaves (deciduous trees) | Trees with needles (coniferous trees) |
| Growth | Grows slowly – denser, stronger wood | Grows faster – less dense, easier to work with |
| Grain | Usually tighter grain, rich colour and texture | Typically lighter grain, more uniform |
| Examples | Oak, Mahogany, Beech, Walnut | Pine, Cedar, Spruce, Fir |
| Cost | Generally more expensive due to slower growth | Generally cheaper and more sustainable |
Hardwoods are typically used for:
- High-quality furniture
- Flooring and doors
- Decorative finishes and veneers
- Musical instruments
- Tool handles
Softwoods are typically used for:
- Structural construction (e.g. beams, roof trusses)
- General DIY projects and shelving
- Interior trim, paneling, and cladding
Sustainability
- Softwoods grow faster, making them more sustainable for mass production.
- Many hardwoods come from tropical regions and must be sourced responsibly (e.g. FSC-certified).
Forestry Stewardship Council (FSC) certified wood comes from responsibly managed forests that protect the environment and support local communities.
Polymers
Definition
Polymers
Polymers are synthetic materials made from chemical compounds that are commonly known as plastics.
- Human-made / synthetic material
- Sourced from petrochemicals (crude oil derivatives) or increasingly from renewable sources like corn starch or sugarcane (bioplastics).
- Polymers are broadly classified as either thermoplastics or thermosetting plastics, depending on how they respond to heat and moulding.
| Feature | Thermoplastics | Thermosetting Plastics |
|---|---|---|
| Heat Response | Soften when heated, can be reshaped multiple times | Harden permanently after being set, cannot be reshaped |
| Recyclability | Recyclable | Not recyclable once set |
| Typical Uses | Bottles, plastic bags, packaging, casings (e.g. ABS cases) | Electrical fittings, adhesives, circuit boards |
| Examples | Polyethylene (PE), PVC, Acrylic, ABS | Epoxy resin, Melamine, Bakelite |
| Structure | Linear or branched polymer chains | Cross-linked polymer chains |
| Advantages | Flexible, lightweight, recyclable | Strong, heat-resistant, durable |
| Disadvantages | Can deform at high temperatures | Brittle, cannot be remoulded |
- Don't assume all polymers are non-biodegradable.
- Biodegradable polymers (Bio-plastics) like PLA are designed to break down under specific conditions.
Metals
- Naturally occurring, extracted from ores in the earth’s crust.
- Metals are good conductors of heat and electricity.
- They are generally strong, durable, and malleable.
- Metals are classified based on iron content:
- Ferrous metals: contain iron
- Non-ferrous metals: do not contain iron
- They are often combined into alloys to improve performance for specific applications.
| Classification | Ferrous Metals | Non-Ferrous Metals | Alloys |
|---|---|---|---|
| Examples | Mild steel, Cast iron | Aluminium, Copper, Zinc | Brass, Stainless steel |
| Key Properties | Strong, tough, magnetic, can rust | Lightweight, corrosion-resistant, good conductors | Enhanced properties (e.g. rust resistance, strength) |
| Common Uses | Construction, tools, car bodies | Wiring, cans, roofing, plumbing | Cutlery, instruments, decorative fittings |
Glass
Definition
Glass
A hard, brittle and typically transparent amorphous solid made by rapidly
cooling a fusion of sand, soda and lime.
- Human-made material made by heating sand and other minerals until molten, then cooled to form a solid.
- Key properties: transparent, hard but brittle, chemically resistant, and poor heat conductor (unless treated).
- Common Types of Glass:
- Float Glass: flat, standard glass for windows
- Tempered Glass: stronger and safer when broken (e.g. car windows)
- Laminated Glass: holds together when shattered (e.g. windscreens)
- Borosilicate Glass: heat-resistant (e.g. lab glassware, cookware)
