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MATERIALS

WOOD

TECHNOLOGY DEPARTMENTMara Dolores Garca FernndezI.E.S. ALJANADIC

From Simple English Wikipedia.Drawing from Oxford UP

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The primary material types used are woods, metals, plastics, ceramics and composites.

Each of these has its own characteristic working properties such as strength,

malleability, conductivity, hardiness and durability.

Types of materialsYou need to be familiar with the different properties offerrous and non-ferrous

metals; softwood and hardwood timbers; and thermoplastics and thermoset plastics.

When working with resistant materials you need to be able to choose the best material

for a job. Wood, metal and plastics are the most common materials used, followed by

composites and ceramics.

The main classification of materials is given in the chart below. You need to know these

terms and their definitions.

Material classification diagram

Plastics

Plasics are divided into thermoset plastics and thermoplastics. The main difference

between the two is that thermoplastics can be heated and shaped many times, while

thermoset plastics can only be heated and shaped once.

Composite materials

Composite materials are formed by combining and joining of two or more materials - a

reinforcing material and a bonding agent such as glue. MDFis an example of composite

materials. Remember: alloys are not composite materials.

Metals

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Metals can be eitherferrous ornon-ferrous. Ferrous metals contain iron while non-

ferrous metals do not.

Both ferrous and non-ferrous metals are divided into pure metals and alloys. A pure

metal is an element - eg iron, copper, gold - unalloyed (not mixed) with another

substance. An alloy is a mixture of two or more elements (eg, iron and carbon) to makeanother metal with particular properties (eg steel).

Ceramics

Ceramics are made from clay, sand and feldspar. These materials are ground to a fine

powder, mixed together and fired at high temperatures (700 - 2000C) in the production

process.

Timbers

Timbers are divided into hardwood timbers and softwood timbers. Hardwood timbers

get their name because of their cellular structure when seen under a microscope - not

because they are hard to cut. Softwoods do not have this same hard cellular structure.

Working properties

Different materials exhibit different working properties. Listed below are the key

properties which determine how materials behave. You need to know what each of

these terms mean.

Conductivity

The ability of a material to conduct heat or electrical energy.

Strength

The ability of a material to withstand a force without breaking or bending.

Elasticity

The ability of a material to bend and then to return to its orginal shape and size.

Plasticity

The ability of a material to permanently change in shape.

Malleability

The ability of a material to permanently deform in all directions without cracking.

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Other terms you should know

Ductility is the ability of a material to deform, usually by stretching along its

length.

Hardness is the ability of a material to resist wear, scratching and indentation.

Toughness is the ability of a material to withstand sudden shocks without

breaking.

Durability is the ability of a material to withstand wear, especially as a result of

weathering.

Fusibility is the ability of a material to change into a liquid or molten state when

heated to its melting point.

Timbers

There are two types of timber: softwood and hardwood.

Softwood timbers usually come from coniferous trees - that is, evergreen, needle-

leaved, cone-bearing trees such as fir and pine. They do not have the hard cell structure

that gives hardwood trees their name.

Hardwood timbers come from broad-leaved, deciduous trees, and are more important

in Design and Technology than softwood timbers. The main hardwood timbers are,

beech, cherry, mahogany, oak and teak.

Artificial wood planksIt can defined as wood products manufactured by glueing together wood particles (

wood chips ) or fibres

Plywood

Fibreboard or chipboard

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Plywood is a type of composite wood

made from thin sheets of

wood.Alternative layers are glued

together so they have their grain

at right angles to each other forgreater strength

Fibreboard is made of a mixture of glue and

wood fibres.It much cheaper than natural wood

because it is made from wood chips. Fibre

board is mainly used in the furniture industry.

For pieces that will be visible, a layer of wood is

often glued onto fibreboard to give it the

appearance of conventional wood ( See image

above ).

Wood:

Wood is a solid material derived fromwoody plants.

A place that has many trees in it thatare close together is called forest.

Wood is very easy to cut, but it is verystrong. After a tree falls, the wood canbe cut into long and straight piecescalled lumber.

Wood is used for:

Construction of buildings (walls, floor,doors,)

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Furniture (chairs, tables, wardrobes)

Musical instruments (violin, piano, guitar,cello..)

Making fires.

When someone builds something with wood, they usually paint it. Paint protectswood and makes it more beautiful.

There are different kinds of wood. There is a relationship between the propertyof the wood and the property of the tree

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Fir tree Mahogany tree Cherry tree

Poplar Beech tree Pine tree

Oak tree

Tree growth.

A tree increases its diameter by formation, we can see the growth ring.

You can see the growth ring in a cross-section

Cambium

Bark

Growthrings

Heart

Sapwood

Heartwood

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New sapwood is created during each growing season, after 2 o 3 years thiswood becomes part of the heartwood.

Bark: Protective tissue of trees and other woody plantsCambium: Plant tissue that produces phloem and xylem cells

Phloem: Cells that transport organic nutrientsXylem: Cells that transport water and mineral nutrientsSapwood: Newly formed, wood between the heartwood and cambiumHeartwood: Dead central portion of wood in a tree.Heart: The centreKnot: Is a particular type of imperfection. A knot is a portion of a side branch.HOW DO YOU GET THE WOOD?

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.Classification:

Hard (poplar tree, beech tree, oak tree, mahogany tree, cherrytree)

Soft (fir tree, pine tree)It is said that hard wood comes from deciduous trees.

Wood

We need some steps

to use it

To cut down a tree

To transport it

To cut it

To let it dry

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It is said that soft wood comes from evergreen trees. But this isnot always the case.

Products made of wood:Chipboard

CardboardPaper

When working with wood you need:To measure and mark itTo hold itTo cut and to drill itTo file itTo join the different piecesTo finish your work up

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Wood activities

1- Label the cross-section diagram below

2- Complete the crossword

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4- How do you know if a tree is a deciduous tree or anevergreen tree?