materials for technical use wood
TRANSCRIPT
Technology Departm
ent I.E.S. El M
olinillo G
uillena
Materials for Technical Use : Wood
Wood
Historical Introduction:
Wood is a natural material. Wood and stone were the first materials that man used.
Wood is used to light a fire, to make weapons, to build houses, etc.
Some of these things are used today.
The Tree’s Trunk
Bark: the outer trunk´s part. It is a protector of the trunk..
Medullary Rays: they are cracks from the center outwards.
Medulla: the inner trunk´s part.
Heartwood: the best quality part.
Sapwood: part of the trunk with life. It´s the youngest part of the wood. Its colour is light. It has a lot of sap.
Wood
Cut down the trees
Transport
Clean the branches and the bark
Cut the wood
Dry it
Distribution
Life rings let us know tree´s age. The clearest rings belong to spring and the darkest ones belong to autumn.
Wood
Obtaining Wood
We can extract wood from a tree that is not too young or too old, it depends on the different species
To extract wood we follow these steps:
To Cut Trees.
Wood
•The tools to cut trees were the axe and the hand saw.•The tools used today are the chainsaw and big machines that cut and raise the trunk quickly.
The trees are cut in the winter, because they have less sap.
Wood
To Cut Trees.It is necessary to plant trees again to have wood in the future. This prevents deforestation.
Cleaning the trunks
Wood
Today the trunks are transported by big lorries.
From the beginning the trunks were transported by the rivers´ flow.
Transportation
First the trees are cut down and then the branches and the bark are cut.
To cut the wood
Wood The tools to cut the wood are:
traditionally circular saws and today big electrical machines or machines with engines.
The trunks go to the sawmill. Here the worker marks the lines to cut the wood. This woodcutter makes planks, boards, beams, etc.
The distribution of wood
Wood
Drying the wood
After cutting the wood, It´s necesary to dry in order to evaporate the sap and the water. The wood is stacked to allow air to flow.It is faster with hot air.
The cured wood is taken to the factories.
Properties of wood
Wood
•The wood is hygroscopic.•The wood is a bad conductor of electricity and heat. So the wood is a good insulator.•Most wood has medium density (<1000 Kg/m3),except some like the ebony and other tropical wood.•There is very soft wood like that of poplar trees or balsa and very hard like oak or ebony.•The wood has good mechanical endurance in parallel direction to the fibres and less mechanical resistance in perpendicular direction to the fibres.
•Durability: there is wood that is very resistant to fungus and parasites like walnut, mahogany…and there is other wood less durable like pines and eucalyptus.
Some interesting web links:• Wood´s Web (ES)• Wood´s Kinds (ES)• Wood in Kalipedia (ES)• Wood´s Kinds 2 (EN)• Wood´s Kinds 3 (EN)
Wood
Types of wood:The most common classification of wood is :•Soft wood: resinous and evergreen trees, they are easy to work with (pine, fir, poplar…)•Hard wood: deciduous trees like oak , walnut, ebony,…
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Types of wood:Exercise: make a Power Point or an Impress presentation with the different kinds of wood . You must show the main properties and applications of every one.Below you can see an example in Spanish.
Wood
Wood DerivativesArtificial Boards:• Cheaper than natural wood.• Completely flat and smooth.• Bigger size than natural wood.• Will not rot and it´s termite resistant.
Plywoods: Made with wood sheets with perpendicular fibers and are stuck together. These boards always have an uneven number of sheets.
Wood
Wood DerivativesChipboards: Made with glued and pressed wood shavings. We can paste plastic or natural wood sheets together to get a best finish quality.
Fiber Boards: We can get them from wood fibers pressed together by high pressure and glued by synthetic resin (DM) or natural resin (tablex).
Wood
Wood DerivativesPaper:• Resistant• Enduring• Hygroscopic• Light• Heat insulator • Electric insulator.
Cardboard:•Obtained from a thick sheet of pulp paper.• Light and resistant.• Used in packaging.
Woodworking
To cutTo fixTo measure and to mark
To smoothTo drillTo split
To finish
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Woodworking Tools:
To measure and to mark
To fix
• Compass• Flexometer• Square
Vise, bar clamp and C-clamp.
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To cutHand Tools: Rip saw, backsaw and hacksaw.
Power Tools: circular saw, jigsaw and table saw.
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Woodworking : Tools
Wood Machining
Woodturning
Router/Milling Machine
Gouges
Router bits to mill
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Woodworking : Tools
To smooth Rasps: with different sections.
Sandpaper Electric sander
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Woodworking : Tools
To drill
Wood auger
Hand drill
Drill bits
Electric drill
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Woodworking : Tools
To split
Nailing
Screwing
Hammer
Screws
Wood
Woodworking: Tools
Screwdrivers Powered screwdriver
To split
Gluing
Paste
Wood
Woodworking : Tools
Finishing
Varnishing
Waxing
Painting
Wood
Woodworking : Tools
© Antonio Jesús Romero &Juan Antonio Tierno 2010