Lesson video

Hello there, my name is Mrs. Dhami.

Thank you for joining me for your Design and technology lesson today.

Now, the big question for today is, where do metals come from, and what forms do they get processed into for us to be able to use? So, hard hats on.

Let's get exploring.

Our outcome for today is we will be able to describe where different materials come from and identify their common stock forms. We have four keywords today, source, which is where a material originates from, raw material, which is a natural material in its original state, process, which is changing a material to make it suitable for making products, and lastly, stock form, which is the standard shape or size a material is supplied in.

We have two learning cycles for today, sourcing and processing materials and then material stock forms. So let's get started with sourcing and processing materials.

Source is one of our keywords today.

So a source is where a material originally comes from.

Metals occur naturally and are mined from the earth.

Metal raw material fall into two different types.

We have ores, which are basically rocks that contain metals or metal compounds, such as iron ore, and the ores themselves are mined, and you can see one of those mines in the picture on the right-hand side.

We also have native metals.

Now, native metals are those that do not require any extraction, such as gold.

Now, you might have heard that phrase panning for gold, where you put a load of bits into a pan and you shake it in the water and basically it removes the gold from the sediment because the gold is a lot, lot heavier.

So you can actually pick out bits of gold 'cause they're not attached onto the rock, and they are native metals.

If it's an ore, the metal must be extracted from the ore and processed.

So what does an ore look like? We have iron ore, also known as hematite, we have copper ore, known as malachite, and then we have tin ore.

If you look really carefully at these three different ores, you'll see sparkly bits within them, and that is the metal that needs to be extracted.

There are several processes for extracting metals.

For copper and silver, we have chemical reaction, zinc, iron and tin, carbon reduction, aluminium, sodium, and magnesium, we have electrolysis.

Now, I'm gonna explain each of those methods in a bit more detail over the next few slides.

But one thing to point out, starting with chemical reaction, that it is extremely easy to extract, whereas as we work our way down to carbon reduction and then to electrolysis, it gets more and more difficult to extract.

Basically the higher the reactivity of the metal, the harder it is to extract.

Let's start with the easiest to extract method, and that is extraction by chemical reaction.

Some metals can be extracted from their ore through a process called smelting, which basically involves heating them to a very high temperature.

This can release toxic compounds into the environment, which can be dangerous.

So for example, copper is found in an ore called copper sulphide.

The sulphur dioxide escapes as a gas when heated, leaving the pure copper behind.

Moving on to carbon reduction.

Now, the image on the right is of a blast furnace.

So let's take a look at what happens within that blast furnace.

So firstly, the iron ore, coke, and limestone are added from the top.

Hot air is then blasted in from the bottom to burn the coke and produce carbon monoxide.

This gas then reacts with the iron ore to extract the iron, and you can see it coming out as molten iron at the bottom, in the process called smelting.

So that's similar to the one on the last slide.

Now, limestone removes the impurities to form slag, which is a byproduct, and the waste gases are released at the top.

And finally, we have the most difficult extraction process, which is electrolysis.

Now, in electrolysis, an electric current is passed through a molten or dissolved substance.

This process splits it into its elements.

Let's take a little look at the diagram in a bit more detail.

The positive metal ions are the orange ones with the plus inside.

Now, these move to the blue cathode, which is the negative electrode.

We then have the negative, non-metal ions, which are the blue ones with the negative sign inside.

They move to the positive electrode, which we call the anode, which is the orange anode.

Useful metals like aluminium can be extracted this way.

Time for a quick check-in.

Iron ore, hematite, is mined.

Which extraction method is used for iron? Is it A, chemical reaction, B, carbon reduction inside a blast furnace, or C, electrolysis? Have a think.

Come back to me when you've got an idea.

Well done if you got B.

Iron is extracted from iron ore by using carbon reduction inside a blast furnace.

After metals are extracted and refined, they are melted and cast into something called ingots.

Now, you can see a picture of the ingots on the right.

Ingots are large, solid blocks of metal.

These ingots can then be reheated and processed into blooms, slabs, and billets, which are all different shapes and sizes, before being made into their final stock forms, which is usually how we end up buying them.

So the ingots turn into blooms, slabs, and billets.

Take a little look at the different shapes between them.

Now, as I said on the last slide, they then become and are made into different stock forms. So for example, blooms tend to become structural beams, such as I-shaped cross sections, slabs turn into sheets and coils, and billets turn into bars, rods, and wires.

And we'll talk more about stock forms in our second learning cycle today.

Metals can be categorised as ferrous, non-ferrous, and alloys.

And we're going to talk a little bit about each of these in a bit more detail on the next slide.

My question to you is can you identify any examples of each of these categories from this collection? Think about what you've learned in design and technology over the years, and think about what materials you have used and come across.

Take a minute to perhaps chat to the person next to you.

Pause the video.

Come back to me when you've got a few ideas.

Okay, let's draw us back together.

Hopefully you've had a chance to talk about different metals and perhaps you might have been able to identify a few of those.

Perhaps you identified on that reel, the reel of solder.

Perhaps you've done a bit of electronics in some of your lessons and used solder to be able to join up those components to make a circuit work.

Now, solder is an example of an alloy.

Ferrous metals are a mined metal that contain iron.

They have to contain iron to be classified as ferrous.

Most are magnetic and rust, unless they are an alloy, which means they contain iron and something else, like stainless steel and wrought iron.

So you might recognise the vice, the vice that you perhaps have in some of your workshops, perhaps your metalworking workshop, is made from cast iron.

We then have cutlery which is made from stainless steel.

Now, stainless steel, as I said, is an alloy.

It has iron in it, but it also has chromium, magnesium, and nickel.

We then have non-ferrous category.

Non-ferrous are a mined metal that does not contain iron.

Therefore, it's not magnetic but it has a higher resistance to rust and corrosion.

Two lovely examples are aluminium, obviously we don't want the aluminium cans rusting with drinks inside, and then copper.

Both of these are non-ferrous.

Alloys are manufactured by mixing metals or combining with other elements to make them stronger, harder, lighter in weight, or better in some way.

So you cannot mine an alloy because they have to be mixed, whereas ferrous and non-ferrous materials, metals, sorry, can be mined.

So some examples of alloys, brass.

Brass is made from copper and zinc combined, and you might have seen that in padlocks or perhaps some musical instruments.

We then have solder, as I talked about a little while ago, that is an alloy of lead and tin, well, that's one combination of solder anyway, and solder, as we've talked about before, is used to join electronic components.

Metals can also be heat treated to modify their properties.

So for example, we can anneal metals, which means heating them up to a certain temperature to soften and improve their malleability, which is really important, say, in jewelry-making when you need to be able to soften it so that you can work it into different shapes.

Which of the following best describes an alloy? A, a pure metal found naturally in the earth, B, metal that has been reshaped, C, mixing metals or combining with other elements, or D, metal that has been coated in plastic for protection? Have a think.

Come back to me when you've got an idea.

Well done if you've got C.

An alloy is a mixture of metals or a mixture combining with other elements.

The main sources of iron are found in USA, Russia, Sweden, China, and you can see those highlighted in purple on the map.

China, however, is the main manufacturer and processor of steel.

The main sources of aluminium are USA, France, and Australia.

And the main sources of copper are the USA, Chile, Zambia, and Russia.

Let's take a look at the sustainability and environmental impacts of metals.

Metal products do tend to be more durable, which means that they last a long time and reduce the need to replace parts or products so frequently.

Best example of that is water bottles.

Quite often the metal water bottles are a lot more durable than the polymer alternatives.

Most metals can be recycled, and when they are melted down, the quality remains just as high as the original metal.

This is different from materials like paper and polymers which often lose some of their quality during recycling.

Metals are considered a finite resource, so designing products to be easily dismantled or encouraging recycling is important.

During mining and extraction, often habitats and landscapes will be destroyed.

It can also cause soil and water pollution due to chemicals and waste, and it uses lots of energy, especially in blast furnaces or through electrolysis.

Carbon emissions.

Obviously, it's high energy use, which is often from fossil fuels, therefore it leads to carbon emissions which contributes to global warming.

As for waste, during extraction, there is a lot of waste rock, but also the byproduct slag if it is through a blast furnace.

And then if the metal is not recycled after use, metals will add to landfill, which takes away valuable landscapes.

Onto task A.

Part one, I'd like you to explain the difference between a raw material and a processed material using metals as an example.

Part two, I'd like you to explain the terms ingots, blooms, slabs, and billets, and part three, using a diagram, explain how iron is extracted from its ore using carbon reduction.

Good luck.

Come back to me when you've got some great answers.

Answers could include, so for part one, explain the difference between a raw material and a processed material using metals as an example.

So a source is where a material comes from, like iron ore, which is the natural rock containing metal found in the earth.

The ore is the raw material.

After processing, such as heating the ore in a blast furnace to extract the iron, the result is a processed material like pure iron or steel, which can be used to make products.

Part two, I asked you to explain the terms ingots, blooms, slabs and billets.

Answers could include, after metals are extracted and refined, they are melted and cast into ingots, which are large solid blocks of metal.

These ingots can then be reheated and processed into different stock forms, such as blooms, which are used to manufacture structural supports, slabs, used for rolling into sheets and plates, and billets, used for making rods, bars, and wire.

Part three, I asked you, using a diagram, explain how iron is extracted from its ore using carbon reduction.

So iron, first of all, is extracted from iron ore by carbon monoxide reduction.

In a blast furnace, iron ore, coke, and limestone are added from the top.

Hot air is blasted in from the bottom to burn the coke and produce carbon monoxide.

This gas reacts with the iron ore to extract the iron in a process called smelting, and then limestone removes impurities to form the byproduct of slag.

Onto learning cycle two, which is material stock forms. A stock form is a standard shape and size in which a material is supplied.

Standardising means that the shape and size of the material are made to specific dimensions.

Stock forms allow designers and manufacturers to know which form a material is available in.

This information is required when designing a product and planning its manufacture.

Metal stock forms include the following.

We have round bar, which is solid cylindrical, so for example it's used in rails and support rods.

We have tubes, which are hollow cylindrical, so for example, bike frames, plumbing, scaffolding.

We then have wire, which is a thin flexible metal strand, for example, electrical wires.

You quite often see them, don't you, inside those bright-colored plastic outer tubes? And then there's lots of little thin wires sticking out.

And it's also used within jewellery.

We then have T sections.

So, that has a T cross section, for example, load-bearing structures, and it's they're used in construction supports a lot.

We then have RSJs.

Now, if you've ever had any building work done within your home, you are likely to have had an RSJ put if you've got rid of a wall.

So, RSJs, for example, the I cross-section, are used in building frameworks, bridges, and structural supports.

We then have channels which can be C or U cross sections.

And again, they're often used as construction supports and also in vehicle chassis.

We then have sheets which are thin, flat metal sheets.

So for example, used on car body panels or signage.

We have square bar, which is a solid square section, which is used, for example, with frames or brackets.

We have flat bar, which is a rectangular strip, for example, in braces and supports.

We have angles, such as an L cross section, for example, in frames, brackets and shelving.

We have box section, which is a hollow square or rectangular tube, for example, within gates or support structures.

And then we have a hexagonal bar, which is a solid six-sided bar, for example, with fasteners, nuts and bolts, and tool handles.

What does standardised mean? Is it A, made in different shapes and sizes every time, B, made the same way every time so it fits and works well, C, made only by hand, or D, made to be thrown away after one use? Have a think.

Come back to me when you've got an idea.

Well done if you got B.

Standardise means that it's made the same way every time so it fits and works well.

There are many benefits to materials being available in a range of stock forms. Handling, they are easier to store and transport.

You know how much space they're going to take up, you can calculate how many you can have and how many you can store and have space to store.

Cost, bulk production of standard sizes lowers cost.

Waste, you only buy what is needed.

You are not left with loads and loads of excess because as long as you calculate it right, you know how much you need to buy.

And lastly, efficiency, consistent sizes are easier to work with.

Let's say you want to die cut a thread onto a piece of metal rod.

Let's say the die cutter that you have is six mil, therefore, you're going to buy rod with a six-mil diameter.

It's efficient, you know it's going to work with what you've got.

Most stock forms of metal come in the following standard sizes.

Sheets are measured in length and widths, so for example, 500 by 500 millimetres or 1,000 by 2,000 millimetres.

Thicknesses, for example, sheets normally come between 0.

5 and 6 millimetre thicknesses.

Bars, the width tends to be between 10 to 100 millimetres.

Thicknesses tend to range between 3 and 25 millimetres.

Rods and tubes, they're normally measured by their inner and outer diameters.

For example, between three millimetre diameter up to about 100 millimetre diameter.

But there's, of course, exceptions with all of these two.

What is one main benefit of using materials in standard stock forms? A, it ensures all products made from the material will have identical properties, B, it eliminates the need for quality control, C, it makes material selection and processing more efficient and cost effective, or D, it allows for completely custom sizing? Have a think.

Come back to me when you've got an answer.

Well done if you got C.

One of the main benefits of using materials in standard stock forms is it means it makes material selection and processing more efficient and cost effective.

Sometimes with material stock forms, you will need to work out how many pieces of a product can be cut from a length of metal, calculate total cost based on length or volume used, and estimate waste left over after cutting.

And this is where our mathematics is really important.

A heating system requires some pieces of copper piping that are 750 millimetres long.

One standard piece of copper piping is 3,000 millimetres long.

So what I'd like you to do is think, how many full pieces can you cut? If you've got a whiteboard or a piece of paper, have a go.

How many can you cut? Come back to me when you've got an answer.

Okay, let's draw us back together.

Hopefully you worked out that the sum we needed to do was 3,000 divided by 750, which gives us four equal pieces.

Well done if you got that correct.

If each 750 millimetre piece costs 2 pound 50, what is the cost of four pieces? Pause the video, have a think.

Come back to me when you've got an idea.

Okay, let's draw ourselves back together.

Hopefully you realise that you needed to times 2 pound 50 by four, which gives us 10 pound as our total cost.

Well done if you got that correct.

When calculating the amount of metal required, there may be occasions when you have to round down.

This is because any leftover metal, called an offcut, is too short and can't be used to make another full length.

And that's really important to keep at the back of any mathematical question in terms of design and technology.

Let's have a go at another example together.

A class are making side tables, and each student requires three legs 985 millimetres long to bend into a hairpin shape.

You can see the legs on the table in the picture in the left.

So the technician orders metal rod in 3,000 millimetre length.

So my question to you is, how many legs can each student cut from one length of metal rod? Pause the video, have a go yourself.

Come back to me when you've had that go.

Okay, let's draw us back together.

Hopefully you remembered about rounding down.

So step one, 3,000 millimetres long divided by 985 is 3.

05.

Step two, we have to round that down to three full legs, and you can see that on my diagram on the right.

Can you see that tiny bit left over? The remaining 45 millimetres is an offcut, which is not long enough for another leg, hence why we had to round down.

Well done if you got that right.

Rounding down still applies when calculating sheet materials too.

Let's try another example.

A tabletop is being water jet cut from a 900 millimetre by 600 millimetre sheet of steel.

So my question to you is, how many tabletops could be cut from one sheet? And you can see the dimensions on the table lid there, that it is 280 millimetres by 280 millimetres.

Have a go.

Pause the video.

Come back to me and we'll move on to the next slide once you've had a go.

Well done with your efforts having a go there.

So, we have our table top dimensions there, and we have our steel sheet underneath.

Let's have a little look at the workings out.

So step one, tops along the length, which is 900 millimetres, is 900 divided by 280, equals 3.

21.

Therefore, we can fit three full tops along the top, which leaves us with 60 millimetres left over.

Step two, along the width, which is 600 millimetres.

So if we take 600, divide it by 280, we get 2.

14.

Therefore, we can fit in two full tops with 40 millimetres left over.

Step three, the total amount of tops, we can have three tops along the length, two tops along the width, which gives us six full tops.

Well done if you got that correct, and a massive, massive well done if you also remembered to write down your working out too.

Time for a quick check-in.

You are cutting 800 millimetre pieces from a 3,000 millimetre length.

How many full pieces can you cut? A, three, B, 3.

75, C, four, or D, two? Pause the video, have a go.

Come back to me when you've got an answer.

Well done if you got three, which is A.

First of all, divide, then check if there's enough for another full piece.

So 3,000 divided by 800 equals 3.

75.

We're really close to four, but we are not quite there and we've got to round down, as there's not enough material, so we round down to three full pieces.

Well done if you got that correct.

Onto task B.

Part one, describe what a stock form is.

Give one example of a stock form and explain how it might be used in a product.

Part two, explain two reasons why metal materials are manufactured and sold in standard sizes.

Good luck.

Come back to me when you've got some great answers.

Part one, I asked you to describe what a stock form is.

Give one example of a stock form and explain how it might be used in a product.

So answers could include, a stock form is a standard shape and size in which a material is commonly supplied.

An example are RSJs used in the construction industry, they are commonly used as load bearing beams in walls, ceilings, or floors when removing walls or creating open plan spaces.

Using stock forms makes it easier and faster to manufacture products, as the material is ready to go and does not require any extra processes.

Part two, I asked you to explain two reasons why metal materials are manufactured and sold in standard sizes.

So answers could include, standard sizes allow manufacturers and designers to plan products more efficiently because the dimensions are predictable.

This reduces time spent measuring or adjusting materials to non-standard lengths.

Using standard sizes helps reduce material waste because products and components can be designed to fit these dimensions, leading to more efficient use of materials and lower production costs.

Question three, an aluminium sheet measures 900 by 600 millimetres.

Heart-shaped decorations, with the below dimensions, are required for a project.

So each heart measures 275 by 150 millimetres.

My question to you is, how many hearts can be cut from one sheet? Remember the methods we used earlier and remember to show your working out.

Good luck.

Come back to me when you've had a good go.

So step one, heart along the length, which is 900 millimetres in the aluminium.

So 900 divided by 150 millimetres equals six.

So therefore, six full hearts can fit onto there with nothing left over.

And you can see that by the diagram, they go right to the edge.

Step two, hearts along the width, which is 600 millimetres.

So 600 divided by 275 equals 2.

8.

That is two full hearts with 50 millimetres left over.

Can I round that up to three? No, it has to be round down to two.

Therefore, step three, the total amount of hearts, six hearts along the length, two hearts along the width, makes 12 full hearts can be cut from that one sheet of our aluminium.

Well done if you got that correct.

Well done if you showed you working too.

This brings us to the end of our lesson today.

Well done with all of your hard work.

Let's summarise what we have found out.

Raw materials need to be sourced and processed into a usable form.

Metals occur naturally and are mined from the earth.

Raw materials for metals include ores, such as iron ore, hematite, and native metals such as gold.

Metal is extracted from ores using a range of processes, such as chemical reaction, carbon reduction, and electrolysis.

Materials are available in a range of stock forms, which influences material selection and production methods.

Rounding down is necessary for calculations because small offcuts can't be used as full pieces.

Well done, as I said, with all of your hard work today, and I look forward to seeing you in another lesson soon.

Take good care.

Bye-bye-bye.