UNIT 4: WOODTechnology Department

COMPOSITION

Wood is made of

Cellulose

Structure of the plant

Lignine

Hardness

Function

COMPOSITION (II)

Top

Trunk

Roots

COMPOSITION (III)

• Parts of a trunkmarrow

core

white

area

cambium

bark

•Wood floats on water.Low density

•Wood absorbs water and it swellsPorousity

PROPERTIES OF WOOD (I)

•Electric insulator•Acoustic insulator•Thermal insulator

INSULATOR

•Ductility: It can be moulded into threads.•Malleable: It can be moulded into sheets.•Tenaciousity: It doesn’t break with hits..

MECHANICAL

PROPERTIES

PROPERTIES OF WOOD (II)

ECOLOGICAL PROPERTIES

Wood is...RECYCLABLE

It can be used again.

BIODEGRADABLE It decomposes in natural

environment.

RENEWABLEIt grows again.

PROPERTIES OF WOOD (III)

PROCESS OF OBTAINING WOOD

CUT INTO

BOARDS

WASH

DRYPLANE

FELL PRUNETRANSPORT

TAKE THE

BARK OFF

PROCESS OF OBTAINING WOOD1. FELL

We fell the tree with an axe or a power saw.

PROCESS OF OBTAINING WOOD2. PRUNE

We cut the branches of the tree with an axe or a power saw.

PROCESS OF OBTAINING WOOD3. TRANSPORT

Logs are transported by road transport, train transport or river transport.

PROCESS OF OBTAINING WOOD4. TAKE THE BARK OFF

We take off the bark of a tree with mechanical rollers.

PROCESS OF OBTAINING WOOD5. CUT INTO BOARDS

We cut branches and trunks into boards of different sizes.

PROCESS OF OBTAINING WOOD6. WASHING AND DRYING

• Boards are submerged in water to eliminate sap and protect wood from bugs.• Boards dry to eliminate water.

NATURAL ARTIFICIAL

PROCESS OF OBTAINING WOOD7. PLANE

We plane boards to make the surface softer.

MANUAL MECHANICAL

STREAKS AND KNOTS

In the wood, we can see:STREAKS: They are the rings of the three.KNOTS: They are the places where there were a branch.

STREAKS

KNOTS

CLASSIFICATION OF WOOD

HARD WOODS•They come from DECIDUOS LEAF

TREES

•Thick trunks

•Great variety of colours.

•Very resistant.

•Very little resin.

CLASSIFICATION OF WOOD

HARD WOODS

Beech Oak

Cherry tree Mahogany

CLASSIFICATION OF WOOD

SOFT WOODS•They come from CONIFEROUS

TREES

• Slim trunks

• Pale colours.

• Easy to work.

• Very much resin.

CLASSIFICATION OF WOOD

SOFT WOODS

Pine Fir

Spruce Poplar

BY-PRODUCTS OF WOOD

•They are made of:WOOD SHAVINGS

•We can find:Prefabricated woodsCellulosic materials

BY-PRODUCTS OF WOOD

PREFABRICATED WOODS

Plywood Chipboard

Grainboard Tablex

• Light• Odd

number of layers

• Very resistant• Heavy

• Very tenacious• Flexible

• Easy to work• Cheap• Bad looking

BY-PRODUCTS OF WOOD

CELLULOSIC MATERIALS

Paper Card

Cardboard Tissue paper

•They are made of CELLULOSE