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 how can metals be reformed into different shapes and different products? So we're going to explore this using some small-scale processes, but also industrial-scale processes.

It's gonna be a lovely lesson with some beautiful examples.

So hard hats on.

Let's get cracking.

Our outcome for today is we will be able to explain and compare small-scale and industrial reforming processes.

We have five keywords today.

Reform, which is when we reshape a material into a new form without changing its basic chemical structure.

mould, which is a hollow shape which can be used to form materials.

Pattern, which is a model of the object to be made, used to form a mould for casting.

Recycle, which is when we convert waste into reusable materials.

And lastly, upcycle, which is when we turn old or unwanted materials or products into something useful, and I've got some lovely examples of that later on.

We have three learning cycles today.

We have small-scale reforming processes, then moving on to industrial reforming processes and ending with how we conserve resources.

So let's get started with small-scale reforming processes.

Reforming processes change the shape or structure of a material without changing its chemical composition.

For metals, reforming usually involves melting and reshaping to create new products in different forms. First check in: Which of the following best describes a reforming process in metals? Is it A: cutting metal into smaller pieces? B: burning metals? C: painting metals to protect them? Or D: melting and reshaping metals to make new products? Have a think, come back to me when you've worked out the answer.

Well done if you got D.

The best way to describe a reforming process in metals is the fact that they are melted and reshaped to make new products.

I'm sure you've probably all heard of 3D printing, but you probably relate 3D printing to polymers.

If you do, you're absolutely correct.

But what you might not know is that you can actually 3D print in metals as well.

So 3D printing is a process of making three-dimensional objects by adding material layer by layer, based on a digital design.

So how does this work? First of all, we create a CAD drawing, CAD standing for computer aided design.

You then download this as an STL file.

You then use slicer software, and there's lots of different types, to generate what we call a G-code.

Now that G-code quite simply are instructions for how to print it layer by layer.

Fused Filament Fabrication, often abbreviated to FFF, is a type of 3D printing process where layers of material are melted and deposited to build objects.

Now, when it's been made out of metal, the filament is made out of metal powder, but that powder is mixed with what we call a binder to stick the little bits of metal powder together.

And that's usually a type of polymer.

Once the file is prepared, it can be sent to print.

So step four, filament is extruded through the heated nozzle.

Step five, the material is laid down a layer at a time onto the build plate, and that process is repeated until the whole object is complete.

Step six, the printed object is then debindered.

Basically this means that the binder, do you remember what binder was? The binder is the polymer bits that stick the metal particles together.

So that binder then is removed, either using heat or chemicals.

We don't need that process when we're 3D printing polymers, but we do need it when we 3D print metals.

Sevenly.

"Sevenly?" Seven, step seven.

Finally, the part is sintered in a high temperature furnace to fully fuse the metal particles together, which leaves a really strong, solid metal object.

You do have to be aware of what we call shrinkage though, because shrinkage during sintering must be accounted for because it can be between 15 and 20%, which really is quite huge.

Metal FFF is used for low cost prototyping, but detailing and complexity is often limited and that's normally because of that huge amount of shrinkage that is involved when sintering.

Time for a quick check-in.

What happens when filament is extruded in 3D printing? A: it cools inside the nozzle? B: it turns into powder? C: it melts and forms layers? Or D: it gets cut and glued? Have a think.

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

Well done if you got C, when the filament is extruded in 3D printing, it melts and it forms layers.

Metal SLM stands for selective laser melting, which basically describes the whole process.

It is a more expensive 3D printing process that uses a laser to fuse powdered metal into solid layers.

So let's take a closer look at how this works.

The green rectangle is that laser and you can see the beam coming out and beam refracted down.

So the laser selectively melts the powder layer by layer to build up the object.

Let's take a little look at a few more annotations.

So you can see there on the right, there is a big kind of bath of powdered metal, and that is being filled up after every time the laser has fused part of it together.

So another layer gets put on top, the laser fuses a bit, another layer gets put on top, the laser fuses it, and that continues until the object is produced.

So the laser only fuses where you want the object to be.

Then the unused powder is great because it actually supports the part during printing, which means that no other support material is required.

Now this is often used for detailed parts in medical implants and aerospace components, and that's why it's so different to the 3D printing with the FFF process that we've just seen, that doesn't give that detail.

Metal SLM gives that beautiful detailed parts because it's so accurate and it does not require any debinding because it directly fuses that powdered metal together.

You may have been lucky enough to have the experience of using pewter casting in your own schools, and I hope that you have.

So pewter casting involves melting pewter, which is a low melting point alloy, and then pouring it into a mould to create detailed decorative or functional items such as jewelry, badges or ornaments.

And it's great because you can make the moulds out of a variety of different things.

So for example, my students have made these pewter-cast flowers, and they designed them on CAD and then we laser cut them into cardboard before pouring the pewter into the mould.

We've also done them using acrylic, where again, we've designed it using CAD and poured the pewter into the acrylic moulds to create beautiful pieces of jewelry, sometimes with acrylic inlays as well.

So let's take a little look at pewter casting in action.

So first of all, step one, we melt the pewter, and you can see I'm doing this on top of the forge just to melt that pewter, and it doesn't take long 'cause it's got such a low melting point.

Step two, we then pour that pewter into a mould and leave it to cool.

The mould is then opened and the product is released, but it's attached to a little sprue.

Now let's zoom into that sprue so that you can see it.

That's the bit that is where the pewter was poured in from.

That's what we call the sprue.

So step four, we have to cut off the sprue to leave our final product, and don't they look beautiful? We can easily draw out those steps as well.

So step one, the pewter is melted.

Step two, the pewter is poured into the mould and left to cool.

Step three, the mould is opened and the product is released, but it is still obviously attached to the sprue.

And lastly, the sprue is cut off to leave the final product.

You can also buy metal as metal clay.

So metal clay is a mixture of metal, binder and water.

Ah, see that word, "binder"? We've come across that before, haven't we, with the FFF 3D printing? So metal clay can be reformed into products such as fine detail jewelry.

Let's take a little look at how it works.

First of all, you shape the clay by hand or by using a mould.

And I've got a silicon mould here that I use with my jewelry club.

The clay is then left to air dry and we normally leave our clay for about 24 hours.

The clay is then fired either in a kiln, if you're lucky enough to have one, or on a brazing hearth to burn away that binder and sinter the metal into a solid metal.

Isn't that similar again to the FFF 3D printing? The metal then has to be polished and it can then be made into a product.

And don't those look beautiful.

My students have done a great job there.

Time for a quick check-in.

I would like you to order the manufacturing steps to pewter casting.

So we have A: open the mould, release the product, B: melt the pewter, C: cut off the sprue, D: pour the pewter into the mould.

Have a think, start ordering them and come back to me when you've got the order that you think is correct.

Well done with your answers.

Let's take a little look at the order, the correct order.

So first of all, we start with B, we melt the pewter.

We then move to D where we pour the pewter into the mould.

A, we open the mould and release the product.

And finally, C, we cut off the sprue.

Well done if you got that correct.

Onto Task A.

Part one, I'd like you to explain what a reforming process is and give two examples related to metals.

Part two, I'd like you to describe how pewter casting can be used in metal reforming.

And part three, I'd like you to compare two small-scale metal reforming processes in terms of their benefits.

Good luck, come back to me when you've got some great answers.

Part one, I asked you to explain what a reforming process is and give two examples relating to metals.

You could have said, a reforming process changes the shape or structure of metal without altering its chemical structure.

Reforming with metals always requires heat.

Examples can include pewter casting and 3D printing.

Part two, I asked you to describe how pewter casting can be used in metal reforming.

You could have said, pewter casting involves melting pewter, a low melting point alloy, and pouring it into a mould to create detailed decorative or functional items like jewelry, badges or ornaments.

Part three, I asked you to compare two small-scale metal reforming processes in terms of their benefits.

You might have chosen the two different 3D printing methods.

So metal FFF uses a filament made of metal powder and polymer, printed layer by layer.

After printing, the part is debindered and sintered to form solid metal.

It's low cost and accessible, but shrinkage during sintering can reduce the accuracy and detail.

Whereas SLM stands for selective laser melting.

It uses a laser to fully melt layers of metal powder, creating highly accurate and complex parts.

It's more precise than FFF as it directly fuses those exact parts, but that also means it's a lot more expensive.

Learning cycle two.

Let's take a little look at industrial reforming processes.

Industrial reforming is used to create metal products on a large scale, sometimes using automated methods.

These methods ensure: speed: mass production is often faster than manual processes.

Accuracy: machines often produce consistent, precise parts.

And consistency: Identical parts can be made repeatedly.

Time for a quick check-in.

Which of the following is a key benefit of using automation for industrial metal reforming? Is it A: it does not require heat? B: it ensures speed and consistent quality? C: it creates unique, one-off products? Or D: it uses hand tools for precise cuts? Have a think, reread those answers, come back to me when you have got the right one.

Well done if you got B.

A key benefit of using automation for industrial metal reforming means that it ensures speed and consistent quality.

This diagram shows hot chamber die casting.

So hot chamber die casting melts metal in a heated chamber and then injects it into a two part mould, which we call a die.

It's used to make lots of small metal parts quickly.

Now you're probably thinking, "Why are you calling a mould a die?" Great question.

Reusable moulds for shaping molten metal are traditionally referred to as a die.

Products include toy cars, like those miniature cars that you might have or you might have had when you were younger, and door handles.

Some industrial reforming processes for metals are not automated, such as: sand casting, where moulds made of sand are only used once.

And then investment casting, for intricate, detailed parts.

And we're going to explore both of these in a bit more detail.

Sand casting is a process where molten metal is poured into a sand mould created by a pattern to create metal parts, and it's often used for large or simple shapes.

Let's take a little look at it in action.

So first of all, a split pattern is created and sprinkled with powder.

Now a pattern is one of our keywords today.

So let's remind ourselves, a pattern is a model of the object which is going to be made and basically it's used to form a mould, ready for casting.

So you've got your pattern there of a kind of rainbow shape.

The sand is then packed around half of the pattern and smoothed off.

The other half of the pattern, and sprue pins are then added and it's filled with sand.

Step five, the pattern and the sprue pins are then removed.

And you might be thinking, "Doesn't all the sand just fall out?" Well no, the sand is compacted so closely that it keeps that shape.

The channels and vents are then added into that sand to allow the metal to flow.

The molten metal is then poured into the mould and it rises up through the sprues and then it is left to cool.

And then finally the casting is removed and any waste from the sprues is cut off.

But it can also be reused.

Products that are manufactured using sand casting include large machinery parts such as gears, brackets and frames, statues, and also garden ornaments.

Investment casting is a process where a wax pattern is coated in ceramic to make a mould, which is then filled with molten metal to create precise, detailed reformed components.

Let's take a look at it in a bit more detail.

So first of all, step one, a pattern mould is prepared.

Remember, a pattern is a model of what we are going to be creating.

Step two, wax is injected into the pattern mould.

Step three, multiple wax patterns are assembled into one, so that lots will be able to be made in one go.

Step four, a liquid slurry coating is applied to the pattern, and you can see it looks like it's been dunked into that slurry.

Step five is stuccoing.

This is where a ceramic powder coating is applied which sticks to that slurry coating.

Now step six is purely a repeat of step four and five.

It's repeated so that it builds up a thick ceramic layer around that pattern.

Step seven, the wax is removed to only leave the ceramic coating, which then becomes a ceramic mould.

Step eight, the molten metal is poured into the ceramic mould, and step nine, that ceramic shell is removed to leave the metal.

Step 10, the metal products are cut off from the assembly.

Step 11, any finishing, especially from where they've been cut off.

And lastly, step 12, they undergo an x-ray inspection to check for any cracks or defects.

Products that are usually manufactured using investment casting include jewelry, turbine blades, dental implants, and small, intricate mechanical parts.

Quick check-in, A pattern for investment casting is made using: A: sand? B: wax? C: metal? Or D timber? Have a think, come back to me when you've worked it out.

Well done if you got B, which is wax.

A pattern for investment casting is made using wax.

Onto Task B.

Part one, I'd like you to match the product to a suitable manufacturing process.

So for the products we have jewelry, dental implants, statues and toy cars.

And as for the manufacturing processes, we have hot chamber die casting, investment casting, investment casting again, and sand casting.

So try and match those ones up.

Part two, I'd like you to compare hot chamber die casting to investment casting.

And lastly, part three, I'd like you to use diagrams to explain the sand casting process.

Good luck.

Try your best.

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

Part one, I asked you to match the product to a suitable manufacturing process.

So with jewelry, hopefully you found investment casting.

Dental implants, hopefully you have found investment casting again, especially due to that high accuracy that they can produce.

Statues, hopefully you found sand casting.

And lastly, toy cars, hopefully you worked out it was hot chamber die casting.

Part two, I asked you to compare hot chamber die casting to investment casting.

You might have said something along these lines.

Hot chamber die casting uses a metal mould known as a die and injects molten metal in using pressure, making strong parts quickly in mass production.

Investment casting, on the other hand, uses a wax pattern coated in ceramic to make a detailed mould, which is good for small, intricate parts.

Part three, I asked you to use diagrams to explain sand casting.

So hopefully you had something with drawings and with annotations that looks a little bit like this.

Step one, the split pattern is created and sprinkled with powder.

Step two, the sand is packed around half of the pattern and smoothed off.

Step three, the other half of pattern and screw pins are added.

Step four, it is filled with sand.

Step five, the pattern and sprue pins are removed.

Step six, channels and vents are added to allow the metal to flow.

Step seven, the molten metal is poured and then left to cool.

And then lastly, step eight, the casting is removed and any waste is cut off.

Well done with all of your hard work on Task B.

Onto learning cycle three, conserving resources.

Metals are non-renewable resources extracted from the Earth's crust.

We can conserve metal resources by either recycling, recycling is where we reprocess used metal products into new materials without needing to extract more raw ore, or we can use upcycling.

Now upcycling is where we creatively reuse scrap or discarded metal items without extensive reprocessing.

So we don't have to basically melt them completely down and turn them into something else.

We could do something different with them.

We can repurpose them.

Both recycling and upcycling prevent waste from going to landfill or incineration, which means being burned.

So both are positive for our environment.

Time for a quick check-in.

Which of the following is a benefit of recycling metals? Is it A: it increases landfill waste? B: it adds strength to a material? C: it reduces the use of raw ore? Or D: it saves energy? Have a think, come back to me when you've got an answer.

Well done if you got C and D.

Benefits of recycling metals include reducing the use of raw ore and it also saves energy.

Waste such as metals can have a detrimental effect on the environment.

Detrimental meaning negative, so a negative effect on the environment, 'cause sometimes metals are thrown away or discarded rather than being recycled.

So if they are thrown away, then they take up valuable space in landfill sites, which obviously we would like to reduce the amount of landfill sites.

If they get discarded into the environment, they can then cause a big danger to wildlife by harming them or by wildlife getting trapped inside of them.

Recycling metals can enable new products to be designed and manufactured.

So let's follow the recycling journey for metal.

So step one, metals are recycled by the user.

So it all depends on the user.

The user making the decision to put that piece of metal, be it an aluminium can or something else into the recycling bin rather than the waste bin.

That decision is crucial for this.

Step two, the recycled metals are taken to the recycling plant where they are sorted into categories, such as aluminium or steel.

Now to sort them, they often use magnets or electricity to make it easier than sorting by hand.

Step three, the metals are shredded into smaller parts.

Step four, the metals are remelted using heat.

Step five, the melted metals are manufactured into stock forms such as hexagonal bar or sheets ready to be made into new metal products.

Now if we take the example of the recycled aluminium can, this is quite amazing.

Recycled aluminium cans can go from the bin that the user has placed it in to the shelf as a new can in as little as 60 days.

Isn't that incredible? Think about that next time you put an aluminium can into the recycling, 60 days later it might be back on the shelf.

Upcycling is one of our keywords today.

So what does it mean? Upcycling is turning something old or unwanted into something useful.

Now you might be sat there thinking, "Well, what's the difference between recycling and upcycling?" If you are, great question.

Recycling, as we've just seen, is when it has to get reprocessed and remelted down and made into a new stock form.

Whereas upcycling takes out that step.

You don't normally remelt it down, you just make it into a new product.

So let's take a little look at an example.

This is one of my dad's old gold cufflinks and I decided to upcycle it into a necklace.

So what did I do? First of all, I cut out a circle to keep his initials on that.

I then heated it up, to anneal it, to make it softer, and I then domed it into a necklace and polished it up.

So I made, and you can see it here in my video, I made an upcycled necklace out of a gold cuff link without remelting it down.

Many artists use scrap and recycled metals to create upcycled installations and metal work pieces.

I'm sure you've probably seen something like this done before, but maybe not out of upcycled metal.

These are those things, you know where there's like holes and you can pop your head through and pretend you've got a different body or you're part of something else.

Well, behind those two blue circles are my two kids and they popped their heads through this upcycled installation.

What I'd like you to do is pause the video.

What can you see that has been upcycled in this piece of art? Come back to me when you've got a few ideas.

Hopefully you identified lots of different upcycled bits and bobs.

Did you notice the spanner as the hand that's holding onto that metal balloon, perhaps? Did you notice the big sieve as the tummy? I'm sure you've noticed both of those and plenty more.

A great example of upcycled metal work pieces.

Time for a quick check-in.

Upcycling and recycling metals are the same.

Is this statement true or is it false? Have a think.

Pause the video.

Come back to me when you've made a decision.

Well done if you got false.

And why is it false? Recycling melts down waste metals into raw materials to make new products.

Upcycling creatively reuses materials to make new products, without melting them down completely.

Well done if you got that correct.

Onto Task C.

Part one, I'd like you to describe two environmental benefits of recycling metals.

Part two, explain the difference between recycling and upcycling metals, using an example of each.

And lastly, draw a diagram that explains the process of recycling metals to create new products.

Good luck with your answers.

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

Part one, I asked you to describe two environmental benefits of recycling metals.

You might have said, recycling metals reduces the amount of metal ore required to process metals and cuts down the amount of waste sent to landfill.

It also means less metals end up in the environment, which can be dangerous to animals.

Part two, I asked you to explain the difference between recycling and upcycling metals, using an example of each.

You might have said, recycling involves melting down metals to produce new materials, such as sheets of aluminium for aluminium cans.

Upcycling reuses metals in their current form, such as art installations using scrap metal or jewelry made from metal products.

Part three, I asked you to draw a diagram that explains the process of recycling metals to create products.

You might have said the following.

Step one, metals are sorted into categories, for example, aluminium or steel.

And this is often done using magnets or electricity.

Step two, metals are then shredded.

Step three, the metals are remelted.

And step four, the melted metals are manufactured into stock forms such as metal bar, ready to be made into new products.

Well done with all of your efforts on these.

This brings us to the end of our lesson today.

Let's summarize what we have found out.

Reforming involves reshaping a material into a new form without changing its basic chemical structure.

Small-scale production methods can be used to reform materials.

Reforming materials on a larger scale require different techniques.

And recycling and upcycling saves resources, reduces waste, and gives life to old materials.

Well done with all of your hard work today.

I hope you have enjoyed it and hopefully see you in another lesson soon.

Take good care.

Bye-bye-bye.