Classwork Exercise and Series (Basic Technology- JSS2): Materials and their common uses

Uses of Wood

Wood can be used in the following ways:

Housing: The doors, windows and roofing of our houses.

Industrial Building: Many industries are constructed with wood, or they have wooden parts.

Joinery: The stair case in our homes.

Packaging: Crates, pallets, packing and cases, etc.

Furniture: Chairs, beds, wardrobes, tables, bookcases.

Transport: Railway wagons, coaches, lorry bodies.

Bridges and poles: Most farm bridges across the roads in villages are made of wood, Also, some electric poles and railway sleepers are made of wood.

Pulp and Paper: Exercise books, textbooks, newspapers, magazines, are made from pulp and paper derived from wood.

Medicine: When people have their arms or legs amputated (cut off), such are usually replaced by artificial limbs made from wood.

Clothing: Most heels and some soles of shoes are made from wood. The rayon stockings and shirts that we wear are made from wood. 

Tool Making: Handles for hampers, pick axes, felling axes, screwdrivers, and many other tools are made from wood.

Some of the uses of ‘Softwoods and hardwoods’

Softwoods

NAME AND ORIGIN	PROPERTIES	USES
Cedar (Asia and Africa)	Reddish-pink colour, Low density, Little grain pattern, Hardwearing under outdoor conditions	In the building industry for roofing and garages, doors and partitions
Pine (North America)	Yellow-brown colour, Clear growth rings, Durable and strong, with high resin content, Weather well	Railway sleepers, heavy gate posts. Decorative panels and stairways. Pattern making joinery.
Spruce (North America and Canada)	Very pale straw/yellow, Fairly durable	Aircraft industry, Ship masts, Interior joinery, Ladders, Packing cases.

Hardwoods

 

NAME AND ORIGIN	PROPERTIES	USES
Afromosia (Africa)	Dark brown colour, Similar appearance to teak, Durable, Easy to work	Ship building, Good quality furniture
Agba (Nigeria and Angola)	Yellow to reddish brown, Straight grinned, Resists decay	Joinery and Furniture, General construction
Balsa (America)	Creamy colour, One of the softest, and lightest of woods.	Model making, Life rafts, life belts, insulation (noise or heat)
Beech (Europe)	Pale pink colour, Hard and close-grained, Good bending qualities, Is attacked by fungus, Weathers well	Furniture mallets, Kitchen utensils, e.g. bread boards, rolling pins.
Ekki (Africa)	Red or dark brown colour, Tough and durable, Resists attack by insects.	Piers pile, dock gates, Bridge building.
Gaboon ( Africa)	Pale mahogany colour, Fairly soft and easy to work,
Iroko (Africa)	Yellowish brown colour, strong and durable, Hard and heavy.	Joinery
Mahogany (Africa, Spain, Honduras)	Lightish to deep red colour, Durable, very good working, qualities.	Cabinet making, Ship building, Panelling, Carving, Wood turnery, Veneers.
Oak (England and Northern Europe)	Golden brown colour, Strong and durable with pronounced grain. Distinctive figure pattern when quarter sawn.	Furniture making, Boat building, Veneers, plywood.
Obeche (West Africa)	Weathers well Creamy white to pale yellow Soft, fairly light Easy to work.	Interior joinery, Furniture, Model making.
Teak (INdis, Burma, Africa)	Darkish brown colour, Strong and durable, Feels greasy because of its oil content. Weather well, Resists attack by insects.	Ship building, Furniture, Laboratory benches, veneers.

Uses of Metals

Metals could be ferrous when it contains iron and non-ferrous when it does not contain iron.

Ferrous Metals

Name	Melting Point 0C	Composition	Properties	Uses
Cast iron	1240	Mixture of carbon and iron, Carbon content 1.5-5%	Vary with carbon content. Brittle with a hard skin. Feel carbon content.	Very suitable for moving parts of machinery because use of the ability of one piece to slide on another due to another the carbon content.
Wrought iron	2000	99% iron with small amounts of impurities.	Malleable and ducile, Elastic, Not very hard, Can be shaped, easily when red hot (forged).	Engine blocks, Haulage gear, Vices, Crane hooks, and chains.
High carbon steel (Tool steel, cast steel)	Varies	99% iron with small amounts of impurities. Mixture of carbon and iron. Carbon content 0.1-0.5%	Malleable and ducile, Elastic, Not very hard, Can be shaped easily, when red hot (forged). Malleable and ductile. Very good working qualities: bends, files.	Haulage gear, Crane hooks and chains, Anchor chains, General constructional works Nuts, bolts, screws, Non-cutting tools steel sheets.
Low carbon steel (Mild steel)	Varies	Mixture of carbon and iron.	Forges and machines well, Harder than low, Carbon steel, Harder as carbon.	All kinds of cutting tools: Steel sheets.

The basic material for the production of ceramics is clay. This is dug out of the ground. After water is added, the mixture is shaken and sieved so that unwanted material, such a stones, is removed. When the clay has settled and drained it is allowed to dry until it is suitable to be worked on.

Clay can be bought already prepared. Red clay contains iron oxide. It has a fine texture and is fired (baked) in kilns at temperature between 900⁰C and 1200⁰C. It is used for making earthenware utensils.

Grey clay has a small amount of iron oxide. It is fired at about 1200⁰C and is biscuit coloured. It is used to make stoneware utensils.

China clay is obtained from kaolin and is white in colour. It has very fine particles and is used for delicate utensils.

Article made from clay usually need to be fired twice. The first time the temperature is about 500⁰C. This derives off excess moisture. The second term, firing is at a higher temperature, and this hardens the utensils.

Uses of Ceramics

From the properties of ceramics discussed in chapter 5, we can easily see that they can be used for many things. Due to the fact that ceramics can withstand very high temperature, they are used in making furnaces. A furnace is a structure or apparatus in which a lot of heat is generated. While the water in an electric kettle boils at about 100⁰C, iron melts at about 1536⁰C. Ceramics can withstand even higher temperatures.

Ceramics can carry heavy loads. As a result of this property, we use bricks and cement blocks to build houses. The walls of any building carry the roof of the building, the top floors, people and decorations.

Most electric poles are made from concrete which is a type of ceramic. The insulator between the lines is also ceramic. Other ceramics are the windscreens of vehicles, ordinary looking glass, television screens and ashtrays. A modern toilet is built entirely with ceramics. The walls are made from concrete blocks, which are ceramics, while the tiles, sinks, baths and toilet bowls are all made of ceramics.

Uses of Plastics

Plastic when hot can be shaped by pressing or squeezing. There a few natural materials that are plastic but most are man-made. There are very many types of plastic with different purposes and these are gradually replacing wood and metals for many articles. Plastic are made from chemicals obtained from natural sources such as water, air, oil, gas and coal. Some of these chemicals have complicated formulae and long names which are so difficult to remember that the makers often call them by simple names, or trade names.

Thermoplastics

Thermoplastics are plastics which become soft when they are heated. They harden again as they cool, but may be reheated, when they will become soft again.

Properties of Plastics

There are some plastics which you can see through easily, and they are said to be transparent like a glass. Others allow strong light through but you cannot see through them. They are said to be translucent, like white plastic carrier bags. Some plastics do not let light through at all, these are said to be opaque. To check whether a plastic is translucent, put it in front of a torch, switch on the torch and look to see whether any light is coming through.

Uses of Plastics

Plastic means something that can be shaped by pressing or squeezing. There are a few natural materials that are plastic but most are man-made. There are very many types of plastics with different properties for different purposes and these are gradually replacing wood and metal for many articles. Plastics are made from chemicals obtained from natural sources such as water, air, oil, gas and coal. Some of these chemicals have complicated.

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