UNIT 2: WOOD AND ITS DERIVATIVES
1. - WOOD Wood is a raw vegetable material. It comes from the trunks of trees and bushes. It´s composed of cellulose fibres (like all vegetable matter) and lignin (which makes it rigid and hard).
1. 1- PROPERTIES OF WOODS Ø
Physical properties
Properties Hardness Density Electrical insulation Thermal insulation Porosity Mechanical resistance Colour and grain Ø
Characteristics Wood is hard, but can be penetrate by objects such as screws or nails Wood is less dense than water, so it floats. Dry wood provides good electrical insulation Wood provides good thermal insulation, but it burns easily Wood can absorb or emit liquids or gases because it has tiny holes (pores) Wood has good mechanical resistance against the forces of traction, compression or bending. Wood has aesthetic qualities: variety of colours and grains
Ecological properties o Wood is a renewable raw material. o Wood is biodegradable. It decomposes as time passes. o Wood is recyclable. We can make other things from it such as prefabricated boards.
1. 2- HOW TO PROCESS WOOD The process starts with the extraction of the timber (raw material) from the forest and ends with the production of planks (used to make objects). CUTTING AND PRUNING
TRANSPORT
The trees are cut down with chainsaws and the branches are then cut off.
The logs are transported by road, rail or water to their destination.
REMOVING THE BARK
SAWING
This happends at the sawmill. A chain of rollers with metal teeth turns and removes the bark
The logs are cut into planks that are cut parallel to the axis of the log.
DRYING
PLANING
The Wood is dried under pressure so that it doesn´t warp.
To make the wood smooth and evenly flat.
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KEY WORDS 1 Raw material: The basic natural we use to manufacture other products. Trunk: The main part of tree from which the branches grow. Grain: The lines we can see on the surface of piece of wood. Board: Flat of piece of wood or recycled material, used in carpentry and woodworking. Timber: another word for wood cut to prepare it for other uses. Plank: Wood cut into a flat board, which can be varying size and thickness.
UNIT 2: WOOD AND ITS DERIVATIVES
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Preparing wood to use 1.
Cutting: We cut wood in different ways depending on what we want to use it for and how we want it to look. Ways of cutting or sawing wood.
2.
Washing: The wood is put in water for a long time to extract different fluids. Drying: The water in the wood is reduced through evaporation. Methods of drying wood:
3.
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 with hot, dry air. This system is quicker and more efficient. c. Mixed drying: this combination of the two methods. First, natural drying is used until the humidity of the wood reaches about 20 % then artificial drying for the last phase. a.
1. 3- CLASSIFYING WOOD Wood is classified as hardwood or softwood depending on the tree it comes from. Ø
Hardwood o Deciduous trees o They grow slowly and have thick trunks o They contain little resin. o They are compact and resist, they can be different colours. o Uses: furniture, doors, windows, scientific and musical instruments.
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Softwood o They grow quickly. o They are light and easy to work with because they are less resistant. o Uses: furniture, boats, building.
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KEY WORDS 2 Extract: Remove, take away, take out from. Pile: A collection of objects lads on top of one other. Humidity: The measurable amount of water in something. Deciduous: Trees that lose their leaves in winter. Resin: A sticky substance found inside wood.
UNIT 2: WOOD AND ITS DERIVATIVES
1. 4- WOOD DERIVATIVES These do not come directly from the cut logs, but from wood sheets fibres or chips that are compressed and glues together. Ø
Prefabricated wood: o o o o o
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Easy to work with. A lot of sizes and finishes. Not attacked by parasites. Helps to protect the environment. Cheaper.
Cellulose materials: These are made from the cellulose in wood. The most important is paper. The illustration on the left shows the process of paper making from wood.
1. 5- ACTIVITIES 1. 2.
What are the two main substances that wood is made from? True or false: a. Wood is denser than water b. Wood provides good thermal insulation c. Wood is used to conduct electricity.
3.
Decide a. b. c. d.
4.
Copy and complete these sentences. Choose the correct option: a. Hardwoods grow more quickly / slowly than softwoods. b. Hardwoods have more / less resin than softwoods. c. Hardwoods are more / less resistant than softwoods.
5.
Listen and repeat these words: logs, planks, piles, thermal, artificial, temperature, ecological. Listen again and tick which words you hear. Remember that the audio is your virtual class.
with your partner which of these ideas are good or bad and why. We can use wood to make furniture We can use wood to make roads We should put wood in water before we saw it. It´s cheaper to dry wood naturally
Logs
Piles
Thermal
Artificial
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Temperature
Ecological
Planks
UNIT 2: WOOD AND ITS DERIVATIVES
2. - EQUIPMENT, TOOLS AND MACHINES These are the steps we follow to make an object out of wood. We need tools and machines. MEASURE
MARK AND DRAW
CUT
DRILL
CARVE AND LEVEL
PAINT
PLANE AND SAND
JOIN OR ASSEMBLE
2. 1- MEASURE, MARK AND DRAW Before you measure, analyse the dimensions and type of type of material you have so you can use it as efficiently as possible. Important measuring tools are the carpenter´s square, ruler, measuring tape, compass.
Carpenter´s square
Measure type
Compass
2. 2- CUTTING AND SAWING Tools for cutting and sawing wood. The choice of tools depends on: • The hardness of the wood • The thickness of the wood • The type of cut we want to make Ø
Type of saws Some saws have a wooden or plastic handle and a metal blade. The blade is rigid. If it has few teeth, they are bigger and make a rougher cut. A bench saw, a jigsaw and a circular saw are power tools used for sawing.
Bench saw
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Circular saw
UNIT 2: WOOD AND ITS DERIVATIVES
2. 3- DRILLING Before drilling, clamp down the piece of wood so that it doesn´t move. Ø
Tools o o
A gimlet is uses to drill thin pieces of wood and to make small holes. A manual drill or carpenter´s brace is used to make more precise hole quickly and with less effort, using different types of drill bits.
Gimlet
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Drill bits
Manual drill
Power tools: drill This makes holes in wood by turning the drill bit electrically with a motor inside the tool.
2. 4- CARVING OR LEVELLING The main function of these tools is to chisel off pieces of wood and make it smooth. Ø
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Tools We use a carpenter´s mallet to hit the handle of the chisels to help carve or level wood. Power tools: plane A plane is made of a cylinder with many tiny blades. These tear off wood chips as the cylinder turns and advances, leaving the wood smooth.
2. 5- PLANNING OR SANDING We need to smooth the surfaces and edges of wood pieces. Ø
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KEY WORDS 3 Drill: using a tool to make a hole in something. Clamp down: Secure something solidly against a table surface with clamp. Drill bit: Thin solid metal cylinder used in the drill to make different size holes Chisel off (vb.): Remove by cutting with a shaped metal hand tool. Chisel: Tool for carving out wood. Sand (vb.): Make a surface smoother by using paper with abrasive sand glued to it. Abrasive: Something that is rough or wears down a surface.
Tools File, sandpaper, plane and teasel. Files can be different shapes: flat, square, round, triangular and half round. We use these different shapes depending on the shape of the piece we want to file. Power tools o A grinder uses a disc made of abrasive material. o A sander uses sandpaper to smooth the surface.
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UNIT 2: WOOD AND ITS DERIVATIVES
Plane
File
Teasel
Sander
2. 6- FINISHES To protect and decorate the wood surface, we add a finish. • For an opaque finish – use paints (oil or acrylic), enamels and lacquers. • For a transparent finish – use stains, varnishes and dyes.
2. 7-ACTIVITIES 1.
Look on the Internet and draw the following objects in your book. a. Awl b. Gimlet c. Chisel
2. Now write a sentence under your picture of each object: a. An awl is used to make a small mark in a piece of wood b. A gimlet is used to …… c. A chisel is used to ….. 3. Answer the questions: a. Which kind of saw would you use to cut out a wooden puzzle? b. Which kind of saw would you use to cut a branch off a tree? 4. Copy the words and match them with the correct definition: DRILL BITS CHISEL PLANE
A tool to make wood smooth A tool used to make different shaped grooves in wood Tubular pieces of metal that you can change in a drill
5. Order the following steps in the process for extracting wood from trees. Cut into pieces – remove the bark – prune the branches – plane the wood – dry the wood – cut down the tree
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