1. Materials p

2. Types of materials Wood, Metal Plastic Stone Ceramic Textile Glass
Synthetic materials

3. Wood Wood is a material that comes from cutting and processing trees.
Use tree trunk (sapwood & heartwood)
Roots, branches, bark→ no commercial value

4. Two principal types Hardwood: - from deciduous trees
(Maple, Oak, etc.)
- used furniture & flooring
Softwood: - coniferous trees (Pine, Fir, etc.)
- residential construction, paper

5. Hardwoods

6. Softwoods

7. Factors Affecting Mechanical Properties
Species, growth rate, moisture content
injuries sustained by tree,
Mechanical Properties (table 12.9)
- hardness, elasticity, resilience, ductility,
malleability, tensile strength

8. Why use wood? Wood easily worked. Wood is easily to assemble.
Wood is a good thermal insulator.
Wood does not conduct electricity.
See p. 375

9. Modified Wood
Modified wood is treated wood or material made with wood mixed with other substances

10. Advantages Stable mechanical properties
More resistance to inclement weather
Manufacture large materials
Can be made from small trees
Wood chips, & wood waste (saw dust)

11. Types Treated Wood- high temp. or copper chem.
(objects in rain or snow)
Laminated Wood
- gluing wood (snowshoes, tables etc.)
Plywood- gluing sheets of wood at right angles (work table, floors)
Particle Board- made with wood chips & wood waste (building construction, trunks, toys)
Fibreboard- wood fibres and smaller bits
(insulation etc. etc.)