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Materials for Technical Use : Wood

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dHistorical 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.

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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.W

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Obtaining WoodWe 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.W

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•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.

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dTo Cut Trees.

It is necessary to plant trees again to have wood in the future. This prevents deforestation.

Cleaning the trunksW

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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 woodW

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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

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dDrying 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 woodW

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•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)

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dTypes 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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dTypes 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.

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dWood 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.

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dWood Derivatives

Chipboards: 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).

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dWood Derivatives

Paper:• 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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dWoodworking : Tools

Wood Machining

Woodturning

Router/Milling Machine

Gouges

Router bits to mill

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dWoodworking : Tools

To smooth Rasps: with different sections.

Sandpaper Electric sander

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dWoodworking : Tools

To drill

Wood auger

Hand drill

Drill bits

Electric drill

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dWoodworking : Tools

To split

Nailing

Screwing

Hammer

Screws

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dWoodworking: Tools

Screwdrivers Powered screwdriver

To split

Gluing

Paste

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dWoodworking : Tools

Finishing

Varnishing

Waxing

Painting

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dWoodworking : Tools