Materials can be selected based upon their working properties. It is important to know and understand which materials can be used for a specific purpose:
Many products are made from metal, and understanding the way each metal will function is vital. For example, if a metal is needed for strength and lightweight properties, then aluminium could be a possibility. Many sports cars are made of aluminium, as are aeroplane shells and wings.
Alloys are made by combining different metals to produce another that is more useful for a specific task. Stainless steel is an alloy of iron and chromium (from 10.5 per cent to 27 per cent). The chromium produces an oxide layer on the outer surface of the steel and prevents corrosion. Stainless steel is often used for kitchen utensils as it will not rust and can be wiped and cleaned with ease.
Metals come from an ore that is mined from the ground. A huge amount of heat energy is needed to extract the metal from the ore - this energy often comes from fossil fuels. Metal ores are non-renewable, meaning they are a finite resource and therefore recycling metal is important.
The cost of metal varies massively and some metals will become harder to obtain in future years. Common metals, such as steel, are relatively cheap, whereas gold and platinum are considerably more expensive.
Metals can be used for all methods of production, from bespoke pieces of jewellery to continuously produced cars. Bulk buying of metal will reduce the cost. Most stock sizes of metals will have a price that is based on the weight of the metal.
If aluminium costs £1,450 per tonne, calculate the cost of a 1 m length of 20 mm2 section aluminium bar that weighs 1 kg.
1,000 kg = 1 tonne, so:
= 1,450 ÷ 1,000
Cost for the metre length = £1.45
Remember to read questions carefully to identify the information that is relevant to the calculations.
Aluminium weighs approximately 2,600 kg per cubic metre (m3).
Based on this, how much would a 1 m length of 20 mm2 section aluminium weigh?
Convert the square section into metres:
20 ÷ 1,000 = 0.002 m
Calculate the surface area of the end:
0.002 m × 0.002 m = 0.0004 m2
The length of the bar is 1 m, so:
0.0004 m2 × 1 m = 0.0004 m3
The weight per cubic metre (m3) is 2,600 kg, so:
2,600 × 0.0004 = 1.04 kg