unit 4. wood
DESCRIPTION
Presentation about wood targeted to 1st ESO students.TRANSCRIPT
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UNIT 4: WOODTechnology Department
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COMPOSITION
Wood is made of
Cellulose
Structure of the plant
Lignine
Hardness
Function
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COMPOSITION (II)
Top
Trunk
Roots
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COMPOSITION (III)
• Parts of a trunkmarrow
core
white
area
cambium
bark
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•Wood floats on water.Low density
•Wood absorbs water and it swellsPorousity
PROPERTIES OF WOOD (I)
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•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)
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ECOLOGICAL PROPERTIES
Wood is...RECYCLABLE
It can be used again.
BIODEGRADABLE It decomposes in natural
environment.
RENEWABLEIt grows again.
PROPERTIES OF WOOD (III)
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PROCESS OF OBTAINING WOOD
CUT INTO
BOARDS
WASH
DRYPLANE
FELL PRUNETRANSPORT
TAKE THE
BARK OFF
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PROCESS OF OBTAINING WOOD1. FELL
We fell the tree with an axe or a power saw.
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PROCESS OF OBTAINING WOOD2. PRUNE
We cut the branches of the tree with an axe or a power saw.
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PROCESS OF OBTAINING WOOD3. TRANSPORT
Logs are transported by road transport, train transport or river transport.
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PROCESS OF OBTAINING WOOD4. TAKE THE BARK OFF
We take off the bark of a tree with mechanical rollers.
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PROCESS OF OBTAINING WOOD5. CUT INTO BOARDS
We cut branches and trunks into boards of different sizes.
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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
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PROCESS OF OBTAINING WOOD7. PLANE
We plane boards to make the surface softer.
MANUAL MECHANICAL
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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
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CLASSIFICATION OF WOOD
HARD WOODS•They come from DECIDUOS LEAF
TREES
•Thick trunks
•Great variety of colours.
•Very resistant.
•Very little resin.
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CLASSIFICATION OF WOOD
HARD WOODS
Beech Oak
Cherry tree Mahogany
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CLASSIFICATION OF WOOD
SOFT WOODS•They come from CONIFEROUS
TREES
• Slim trunks
• Pale colours.
• Easy to work.
• Very much resin.
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CLASSIFICATION OF WOOD
SOFT WOODS
Pine Fir
Spruce Poplar
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BY-PRODUCTS OF WOOD
•They are made of:WOOD SHAVINGS
•We can find:Prefabricated woodsCellulosic materials
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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
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BY-PRODUCTS OF WOOD
CELLULOSIC MATERIALS
Paper Card
Cardboard Tissue paper
•They are made of CELLULOSE