WOOD AND ITS WOOD AND ITS DERIVATESDERIVATES

11ºº ESO BILINGUALESO BILINGUALTECNOLOGIESTECNOLOGIES

IES MIGUEL ESPINOSAIES MIGUEL ESPINOSA

UNIT 4

WOOD AND ITS DERIVATESWOOD AND ITS DERIVATESWOOD

Properties of wood

How to process wood

Preparing wood for use

CLASSIFICATION

Hardwood

Softwood

Wood derivates

EQUIPMENT, TOOLS AND MACHINES

-Measure, mark, draw and secure

-Cutting and sawing

-Drilling

-Carving or levelling

-Planing or sanding

-Joining pieces

-Finishes

1.WOOD1.WOOD

�� Raw vegetable material.Raw vegetable material.

�� It comes from the trunk of trees and bushes. (and branches)It comes from the trunk of trees and bushes. (and branches)

�� It is composed of:It is composed of:

-- Cellulose fibres (like all vegetal matter)Cellulose fibres (like all vegetal matter)

-- Lignin (which makes it rigid and hard)Lignin (which makes it rigid and hard)

�� The parts of a tree trunk you see when you make a horizontal cutThe parts of a tree trunk you see when you make a horizontal cutare:are:

-- Bark (exterior layer): protects the plantBark (exterior layer): protects the plant

-- Cambium: (a thin transparent layer)Cambium: (a thin transparent layer)

-- Sapwood (recent growth): not very strong, used for woodwork thatSapwood (recent growth): not very strong, used for woodwork thatneed soft woodneed soft wood

-- Heartwood (the strong part that keeps the trunk vertical): hard Heartwood (the strong part that keeps the trunk vertical): hard and and dry, extracted and processed for all types of woodworkingdry, extracted and processed for all types of woodworking

-- Pith (the centre of the trunk): very weak, not generally usedPith (the centre of the trunk): very weak, not generally used

1. WOOD1. WOOD

pith

bark cambium

sapwood

heartwood

growth ring

1. WOOD1. WOOD

resin

1. WOOD1. WOOD

1.1. Properties of wood1.1. Properties of wood

Factors that influence the properties of Factors that influence the properties of wood:wood:

1.1.Type of treeType of tree

2.2.EnvironmentEnvironment

3.3.Soil Soil

4.4.Age of the treeAge of the tree

5.5.Composition of the woodComposition of the wood

1. WOOD1. WOOD

�� Physical propertiesPhysical propertiesProperties Characteristics

Hardness Wood is hard, but can be penetrated by objects such as screws or nails.

Density Wood is less dense than water, so it floats.

Electrical insulation

Dry wood provides good electrical insulation.

Thermal insulation Wood provides good thermal insulation, but it burns easily.

Porosity Wood can absorb or emit liquids or gases because it has tiny holes, called pores.

Mechanical resistance

Wood has good mechanical resistance against forces of traction (tensible), compression or bending (flexural).

Colour and grain Wood has esthetic qualities: a variety of colours and grains.

1. WOOD1. WOOD

�� Ecological propertiesEcological properties

Wood is a renewable material, but deforestation causes Wood is a renewable material, but deforestation causes serious damage to the balance of our ecosystem.serious damage to the balance of our ecosystem.

Wood is biodegradable. It descomposes as time passes.Wood is biodegradable. It descomposes as time passes.

Wood is recyclable. We can do other things from it, as Wood is recyclable. We can do other things from it, as prefabricated boards, paper or cardboard.prefabricated boards, paper or cardboard.

1. WOOD1. WOOD1.2. How to process wood

The process starts with the extraction of the The process starts with the extraction of the loglog (raw material) from (raw material) from the forest and ends with the production of the forest and ends with the production of planksplanks (used to make (used to make objects).objects).

1. 1. CuttingCutting and pruning. and pruning.

The trees are cut down with chainsaws and the branches are then cut off.

2. 2. TransportTransport

The logs are transported by road, rail or water to their destination.

3. 3. Removing Removing the barkthe bark

At the sawmill. A chain of rollers with metal teeth turns and removes the bark.

Log: tree trunk that has been cut down for processing or burning.Plank: wood cut into a flat board which can be of varying size and thickness.To prune: process of removing branches from a tree.

Pruning: poda

1. WOOD1. WOOD4. 4. SawingSawing

The logs are cut into planks or boards that cut parallel to the axis of the log.

5. 5. DryingDrying

Under pressure Under pressure so that it doesnso that it doesn´́t warp. Dry wood last t warp. Dry wood last longer and is lighter.longer and is lighter.

6. 6. PlaningPlaning

The wood is planed to make the wood smooth and evenly flat and give it a good finish.

Warp: be deformed because of a process of change.

1. WOOD1.3. Preparing wood for use

After removing the bark, the logs are cut to make planks and boards of different thicknesses.

Washing and drying are important processes to treat the wood.

� The water and the sap are removed and the wood is protected from attacks from insects, fungus, etc.

• Cutting:

We cut on different ways, depending on what we want to use it for and how we want it to look.

Ways of cutting and sawing wood:

Sap: savia

1. WOOD• Washing.

The wood is put in water for a long time to extract (remove, take away, take out from) different fluids (tannin� used for making leather).

• Drying:

The water in the wood is reduced through evaporation.

- Methods of drying wood:

a) Natural drying.

The planks are put in piles, out of the rain and direct sun, with spaces between them so that the air can circulate. This is a slow process.

b) Artificial drying.

The wood is dried in big rooms (dryers) with hot, dry air. This system is quicker and more efficient.

c) Mixed drying.

This is a combination of the two methods. First, natural drying is used until humidity of the wood reaches about 20%, then artificial drying is used.

1. WOODWarping:

These are the ways in which wood can warp:

- Cup

- Crook

- Bow

- Twist

- Split

Warp: combar

Cup: en forma de taza

Crook: acodado

Bow: arqueado

Twist: retorcido

Split: agrietado

1. WOODDifferent cuts of a wood from log:

Log: tronco, leño.

2. CLASSIFYING WOODWood is classified as hardwood and softwood depending on

the tree it comes from.

HARDWOOD:

- Deciduous trees.

- They grow slowly and have thick trunks. (tronco grueso)

- They contain little resin.

- They can be in many different colours, are compact and are resistant.

Deciduous: trees that lose their leaves in winter.

Resin: a stick substance found inside wood.

2. CLASSIFYING WOODTheir most common uses for woodworking:

1. Beech: (haya)

Characteristics:

Heavy and easy to work with. Not very resistant to damp.

Damp: a slightly wet or humit condition.

Uses:

Furnitures, floors, chair frames and legs, handles, toys, matches, rods.

2. CLASSIFYING WOOD2. Oak: (roble)

Characteristics:

Heavy, very hard and resistant.

Uses:

Solid furnitures, doors, windows, wooden floors, parquet, boats, barrels.

2. CLASSIFYING WOOD3. Cherry:

Characteristics:

Not very heavy.

Uses:

Furniture, wall and furniture panelling, wooden floors, scientific and musical instruments (e.g. oboes).

2. CLASSIFYING WOOD4. Mahogany: (caoba)

Characteristics:

Very heavy and long-lasting.

Uses:

Joinery, luxury furniture, hand-carved objects, musical instruments (e.g. guitars).

2. CLASSIFYING WOODSOFTWOOD:

- Conifers (trees with needle-shaped leaves).

- They grow quickly and have clear annual rings.

- The wood is resinous and usually light-coloured.

- It´s light and easy to work because it´s less resistant.

Needle: aguja.

2. CLASSIFYING WOODSome of its most common uses for woodworking are:

1. Pine

Characteristics:

Resistant to changes in temperatures. Easy to work with and resinous.

Uses:

Furniture, boats, electricity posts, floors.

2. CLASSIFYING WOOD2. White fir (abeto blanco)

Characteristics:

Elastic, non resinous and not very resistant to bad weather because it is attacked by fungus.

Uses:

Building, boats, simple furniture, carpentery, boxes, paper.

2. CLASSIFYING WOOD3. Red fir (abeto rojo)

Characteristics:

Light and easy to work with.

Uses:

Fencing, boxes, wood panelling.

Fencing: cercados

2. CLASSIFYING WOOD4. White poplar (álamo blanco)

Characteristics:

Light, soft and not very resistant.

Uses:

Furniture frames, plywood, paper.

Frames: marcos.Plywood: madera contrachapada.

2.1. WOOD DERIVATESDo not come directly from the logs that are cut, but from wood sheets, fibres or chips that are compressed and glued together.

PREFABRICATED WOOD PRODUCTS:

Advantages:

Easy to work with.

A lot of different sizes and finishes.

They are not attacked by parasites.

Made from the leaveovers of wood cutting, so are more ecological and cheaper.

Sheets: thin, flat piece of material.Chip: little piece or fragment of material.

Leaveovers: what remains after the main part has been used.

2.1. WOOD DERIVATESThe most important types:

Plywood:

Thin sheets of wood glued together and compressed.

The fibres in one sheet are at 90º angle to the fibres in the next sheet.

An odd number of sheets are glued together so that the top and the bottom have the same finish.

Very sensitive to humidity and temperature changes.

They can warp and increase in thickness.

Use:

Joinery, doors, packing, agricultural construction, boats.

2.1. WOOD DERIVATESChipboard

Made with wood chips glued together (90% chips and 10% glue) and compressed.

To improve strength and appearance they are covered with a natural sheet of wood or with plastic (melanine).

Fragile and not easily deformed, although occasionally they can bend and increase in volume because some of their components are affected by changes in humidity and temperature.

Use:

Furnishings, doors, ceiling panels, dividing panels, insulation panels for prefabricated buildings.

bend. To become curved or form a curve.

2.1. WOOD DERIVATESFibreboard

The fibres come from milling the wood chips.

This gives tiny wood threads which are compressed and glued together to make a conglomerate.

The fibre planks have different grades of density (medium density, MD, and low density, LD).

Compact, flexible and easy to work with.

Uses:

Exterior covering (because it has a smooth surface), furniture, cabinets, shelving, doors.

2.1. WOOD DERIVATESHardboard

Made from wood left over from the mill, unused pieces of wood.

Compact, flexible and easy to work with.

Uses:

It is compressed together with glue to make lining for cupboards.

2.1. WOOD DERIVATESCellulose materials

Made from the cellulose found in wood.

The most important product made from them is paper.

- Making paper:

Wood is pulped and mixed with water and chemical products to make cellulose paste. Pulped: cut into small pieces and mix with water.

This is compressed and rolled out by a machine until it become a sheet of paper.Rolled out: flattened out with a cylindrical tube or roller.

2.1. WOOD DERIVATESOther cellulose materials:

-Cardboard is made in two ways:

1.By hardening a thick sheet of paper paste.Harden: make hard

2.By sticking together several sheets of paper to make a thicker sheet.

In a similar way we can make:

-Tissue paper (very thin sheets of paper).

-Card (more resistant than paper, but more flexible than cardboard).