Understanding Raw Materials, Manufactured Goods, and Material Properties
Raw Materials and Manufactured Goods
Raw materials are substances extracted directly from natural sources, whether of animal, vegetable, or mineral origin. Manufactured goods are any objects created by humans to satisfy their needs and improve their standard of living.
Types of Materials
Wood
Tree trunks (fir and pine) used for furniture, floors, and paper.
Metals
Ferrous metals: Contain iron (e.g., steel).
Non-ferrous metals: Do not contain iron (e.g., copper, bronze, tin, zinc, and aluminum). Used for structural components, machine parts, tools, electrical components, fixtures, and fasteners.
Plastics
Derived from oil, coal, natural gas, vegetable materials, and animal proteins, and made into cellophane, PVC, and rubber. Used for tubing, packaging, toys, and containers.
Textiles
Natural raw materials (wool, cotton, and silk) and plastics. Used as thread for making textiles with different uses.
Stone
Processed into marble, slate, glass, and plaster in different forms and sizes. Used for construction materials, decorative objects, and sculptures.
Ceramics
Clay made into pottery, earthenware, and porcelain. Used for construction, plates and bowls, sinks, and decorative objects.
Material Properties
Electrical Properties
- Electrical conductivity: Some materials conduct electricity (e.g., metals).
- Electrical insulation: Some materials do not conduct electricity (e.g., wood).
Thermal Properties
- Conductors: Conduct heat (e.g., metals).
- Insulators: Do not conduct heat (e.g., wood).
When the temperature increases, the material expands. When the temperature decreases, the material contracts (e.g., metals).
Fusibility
Some materials change from solid to liquid when their temperature is increased (e.g., glass).
Welding
Some materials can be used to weld two pieces of the same or different materials together (e.g., metals).
Optical Properties
- Opaque: Cannot be seen through.
- Translucent: Allow light to pass through.
- Transparent: Can be clearly seen through.
Most materials reflect a certain color when light shines on them. This is the color we see.
Acoustic Conductivity
The capacity to transmit sound. Insulators do not conduct sound.
Magnetism
Some materials attract other metallic materials, allowing them to become permanent magnets.
Mechanical Properties
- Malleability: Allows a material to be spread into sheets or films.
- Ductility: Allows a material to be formed into filaments or wires.
- Elasticity: Allows a material to return to its original form after a force that has changed its shape is removed.
- Plasticity: Allows a material to be permanently deformed.
Tensile, compressive, shear, flexural, and torsional forces affect material properties.
Wood Composition and Types
Wood is a raw material composed of cellulose fibers, lignin, bark, cambium, sapwood, heartwood, and pith.
Hardwood
Deciduous trees. They grow slowly, have thick trunks, and contain little resin.
Softwood
Coniferous trees. They grow quickly and have clear annual rings. The wood is resinous and usually light-colored, light, and easy to work with because it’s less resistant.
Engineered Wood Products
Plywood
Thin sheets of wood glued together and compressed. The fibers in one sheet are at a 90ยบ angle to the fibers in the next sheet. Very sensitive to humidity and temperature changes, which can cause warping and increased thickness. Used for doors and agricultural construction.
Chipboard
Made with wood chips glued together and compressed. Fragile and not easily deformed, although occasionally they can bend and increase in volume because some of their components are affected by changes in humidity and temperature.
Fibreboard
The fibers come from milling the wood chips. This gives tiny wood threads which are compressed and glued together to make a conglomerate. The fiber planks have different grades of density, making them compact, flexible, and easy to work with.
Hardboard
Made from wood left over from the mill (unused pieces of wood), making it compact, flexible, and easy to work with.