Processing and processed materials

Metals and Non Metals

• Metals
• Gold, brass, silver, iron, copper, lead and aluminium
• Ceramics
• Pottery, glass and poreclain
• Polymers
• Plastic, rubber, nylon, wood, cotton and fabric
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• Bildunterschrift: Metals and Non metals in your notes

Properties of Metals

• Metals are used to make things because of their properties.
• Metals are shiny hard and strong
• You can clean old and dull metals suchs as vases and coins by using brass cleaner, silver cleaner, lemon juice, mixture of salt and lemon juice or a household cleaner. Soft cloth.

Properties of Metals All

• You should know that the metals are shiny
• They are good conductors of the electricity .
• They are good conductors of the heat .
• They have high melting and boiling point .
• They can be bend , They are malleable , And they can be hammered to form sheets .

Properties of Metals

• Metals are malleable which means you can roll or flatten it.
• When metals are heated they can be hammered into different shaps. Flat round gold coins.
• Metals are ductile. Like bubblegum, when you pull it it forms a long thread and does not break.
• Metals are solids and metals are liquids as they melt at high temperatures.

Properties of Non Metals

• Non metals are used to make things because they have certain properties. Glass, clay and of course chalk.
• Chalk was dull and
• Clay and glass were shiny but all brittle
• They are brittle too.
• Properties of Non metals
• Dull
• Brittle

Uses of Metals

• Metals conduct heat (transfer heat energy). Some are magnetic and some are not. Only iron rusts but some metals tarnish or become dull.
• Some materials are good conductors of heat. Heat energy transfers through them easily. Other materials do not transfer heat energy so are not good conductors.
• Non metals such as wood and plastic do not conduct heat well.
• Metals are good conductors of heat and are used to make pots and pans.
• Not a good property if we are trying to stop heat energy transfer.

Some metals are magnetic

• Magnets can pull certain things towards them. We say that the magnet attracts them. When a material is attracted to a magnet, we say it is magnetic.
• Magnetic power drives hairdryers, trains. Some televisions and radios produce sound. computers use the magnets to store information.
• Electromagnet uses electricity to become magnetic. Iron and steel stick to the magnet.

Uses of Metals

• Only iron rusts when exposed to
• wet conditions. Some metals tarnish. Dull not shiny. The metals
• looses its shine and strength when it rusts.
• Metals such as
• copper, brass, aluminium, stainless steel and gold do not rust. Tarnish
• and must be cleaned or rubbed. Metals are used to make things eg
• coins, wire, jewellery, buildings, bridges, cars and kitchen utensils
• and roofs.
• Gold for jewellery, iron for buildings and bridges, tin for food cans, copper for electric wire, silver for knives, forks and spoons.

Metals and Non Metals

• Metals - gold, brass, silver, iron, copper, lead and aluminium
• Ceramics - pottery, glass, porcelain
• Polymers - plastic, rubber, nylon, wood, cotton and fabric
• The material in groups have properties. What the material is like.
• Metals are shiny and strong
• Ceramics are non metals like clay and glass and are brittle
• Polymers are non metals like plastics and fibres and are human made materials

Processing Materials

• If we combine or join materials we get new material with different properties. Eg: when we mix flour and water you get a material that is sticky like glue.
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• Bildunterschrift: Sticky glue

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• If you mix flour, oil and a little water you make a dough that you can model things with.
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• Bildunterschrift: Dough

Mixing and Drying Clay Materials

• There are various ways to combine material to form strong structures. Some homes are made of dry clay and water.
• Straw can reinforce clay to make clay bricks stronger. When mixing concrete we can put in metal bars to make the concrete stronger. This is called reinforced concrete.
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• Materials can be processed to make new materials like concrete. Concrete is
• made by mixing sand, gravel, cement and water. Sand, gravel, cement
• and water are the starting materials. Concrete is the new material.
• When we mix materials in this way we call is processing.
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• Bildunterschrift: Concrete mixing

Comparing Starting Material to New

• Substance Properties before Process Properties after
• mixing mixing
• Jelly and water
• polyfill and water
• Flour and water
• Eg: granular, crumbly, powdery, elastic, wobbly, clear, rubbery, smooth

Processed Materials

• Gloves are used to protect our hands from different things. People choose materials with suitable properties to make their porducts.
• Strength - which materials are stronger. A strong material will not break. Metals are strong but many non metals are also strong.

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• Wood is a strong material. If you put the load in the same direction as the fibres the wood can split.
• Concrete
• is strong when a load pushes downwards on it. Pulling forces can break
• it. A concrete beam has a reinforming rod in the lower part where the
• pulling forces act.
• Glass and ceramics are strong but brittle. They will break if you drop them.
• Plastics are strong. If you try to tea ra plastic raincoat or bumboos you will see the meartials are strong. If you heat plastic, the material melts and becomes weak.

Durability of Materials

• Materials can withstand wear and tear over a long period of time. Long ago knits wore metal armour. Very strong and durable but it weighed a lot. Police use bullet proof vests made from a human made material called Kevlar. Kevlar fibreas are strong and light. Kevlar is also used in the chassis of racing cars which need to be durable, strong and light.
• Fibreglass was firsted used the early 1960 for sailboats. Very durable.
• Plastics are also durable. Platic waste takes many years to break down. Landfill sites are filling up, our beaches are awash with plastic litter and it floats in the oaceans. We should recylce as much as possible.

Materials are Waterproof

Materials are fire resistant

• Some materials do not burn easily. These are fire resistant.
• Materials worn by firefighters. Race car drivers. Kevlar is a fire retardent material. This means it burns very slowly. Fire resistant means it does not burn at all.
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• Bildunterschrift: Firefighter

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• Some
• buildings contain fire retardent materials such as cement and treated
• fibres. This stops the building from burning too easily.
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• Bildunterschrift: Fire retardent building - concrete

Materials used for Interesting Colours

• Most materials can be processed to have interesting colours and textures. Texture is how something looks or feels. Coloured plastics, tiles, glass, fabrics, woven bags and so on.
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• Bildunterschrift: Coloured tiles

Traditional Processing

• People in Africa have been processing materials for hundreds of years.
• Combining soil and water to make clay pots and bricks
• Weaving baskets, hats, mats and thatched roofs from plant fibres
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• Bildunterschrift: Pottery

Making Clay pots and Bricks

• You can make pots by pressing coils of clay together and smoothing them. Coils are rolls of clay.
• Many potters have used this method. One famous potter Nesta Nala. She has gone overseas to exhibit her pottery.
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• Bildunterschrift: Coils of clay

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• She
• uses the coil method. She does not have a kiln or fancy tools or a
• potters wheel to dry and fire her pottery. She uses a method that has
• been used by her grandmother and great grandmother.
• Kiln - furnace or oven for baking pottery and bricks
• Exhibit - show

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• When clay pots dry they become hard. They are very strong. To make them stronger they are heated in a fire.
• Pottery that you buy in in a shop has been fired in a special oven called a kiln.
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• Bildunterschrift: Kiln for clay pots

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• Kilns heat the pots to very high temperatures. Bricks are also made in big kilns at a brick factory.
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• Bildunterschrift: Brick kiln

Using Plant Fibres to make Things

• Woven baskets in Egypt and Middle East are nearly 7000 years old. In South Africa we have excellent examples of woven baskets, hats and fabrics. Best in the world.
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• Bildunterschrift: Weavers

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• Weavers use:
• A bowl of water to soak the plant material of grasses, reeds, rots and palm fibres
• A knife to cut the fibres and split the leaves
• A pounding stone to flatten grass and bend twigs
• An awl or piercing tool to make a hole though which the binding material can pass
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• Bildunterschrift: Traditional weavers

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• Some baskets are made from coils of grass bound tightly together or plaited.
• Others are made from flattened fibres that are woven together.
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• Bildunterschrift: Woven basket

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• Coiled mat - grass tightly bound or plaited.
• Others are made from flattened fibres woven together. A strand of
• grass is wound around a small bundle of grass to make a thick strand.
• Starting in the centre the thick strand is bound round and round. Thick
• thread of grass to used to tie each circle to the circle inside.
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• Bildunterschrift: Coiled mat

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• The main properties of plant fibres that make them so suitable for weaving are that they are flexible and natural. They can be woven in different shapes and sizes.
• Grass absorbs dye well so it is easy to make coloured baskets and mats. Natural dyes from plant material such as bark, roots, leaves and berries are used.