Lesson video

Hello there, my name is Ms. Dhami.

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

Now, the big question today is, what deforming processes are there for polymers? Now, I bet you know more than you think you might do on this, so let's explore it together.

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

We have five keywords for our lesson today.

We have deform, which is a change in the shape of materials when they are put under physical pressure or stress.

We have force, which is a push or pull that can affect the movement, direction, or shape of an object.

We have automation, which is the use of technology to perform tasks.

We have former, which is a solid object that a material is manipulated around to create a specific shape.

And lastly, we have bending jig, a tool used to guide and control the shape of a material as it is bent.

Our lesson is going to follow two learning cycles.

firstly, small-scale deforming processes, and secondly, moving on to industrial deforming processes.

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

A deforming process changes the shape of a material without removing any parts.

It uses heat and a force to shape polymers into a new form.

Deforming polymers makes it easier to create curved or angled shapes that will be hard to cut directly.

And a lovely example of this are yoghourt pots.

Yoghourt pots are made from a deformed polymer, and we'll look at that process a little later on.

Time for our first check-in.

What is a deforming process in manufacturing? A: cutting material, B: joining materials, C: changing shape by force without removing material, or D: adding a coating? Have a think, come back to me when you've got a good idea.

Well done if you've got C.

A deforming process in manufacturing is changing shape by force, but without removing material.

Small-scale deforming processes for thermo polymers often use simple tools, machines, moulds, and formers.

Now, what we're talking about really is processes that would often use in a school workshop.

But before we go any further, let's think about that word in purple, thermo polymers.

Take a minute, can you recall the meaning of that word, and what is the opposite to a thermo polymer? Have a chat to the person next to you.

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

Okay, welcome back.

Hopefully you remembered that thermo polymers are those that can be reheated and then reshaped into a completely different shape.

On the opposite side are thermosetting polymers, which are set in their ways, which means that you cannot reheat them and reshape them.

Instead, they often burn on heating.

So a mould.

Now, a mould is a hollow cavity into which a material is poured or pressed to take its shape, and it's used in processes like injection moulding or press forming.

Now, a mould could just be one side, but it could also be a two-part mould, especially if it's going to be pressed in between, okay? So it could be one part, it could be two part.

Whereas a former is a solid shape over which material is formed or shaped, and it's used in processes like vacuum forming or line bending.

And a former normally only has one side or one part, unlike a mould.

Press moulding is a small-scale deforming process used to create a desired shape.

Now, moulds can be made out of scrap material, and this is a process often done in a school workshop.

So first of all, the polymer is heated.

Now, this is one of my students and they have just made a whole load of HDPE sheets by melting down bottle tops.

And they've made those sheets lovely and thin.

They've cut them up ,and now they are reheating them because they are a thermo polymer.

When it comes out the oven, as long as they don't heat it up too much and it melts, the polymer then is flexible and can be moved.

You can then compress that polymer between a mould.

Notice it says mould and not former.

It's a mould because it's got two parts to it.

So that polymer is compressed between that mould that has been made by one of my students.

And it can produce a variety of shapes depending on what shape that mould is.

And you can see one of my students here has made a beautiful light shade by using press moulding to bend the HDPA, HDPE, sorry, into the right shape.

Drape forming is similar to press moulding, but it uses a former rather than a mould.

So remember, a mould is two part, whereas the former is only one part.

So again, the polymer is heated just like before with press moulding.

The polymer then becomes flexible, and then out comes a former, and that polymer can be placed over the top of the former to cool.

Now, it works and you can get some great shapes of drape forming.

However, sometimes when it cools, sometimes it will spring up a little bit, whereas press forming, because it's a two-part mould, keeps it very tight into that shape.

And that's the difference between the two.

Line bending is a deforming process where a straight line, and only a straight line, on a thermoplastic sheet, is heated using a strip heater until it becomes soft.

It allows it to be bent on that straight line, and only on that straight line, so it's accurate.

It allows it to be bent accurately into shape and then you can hold it in that position until it calls and hardens.

Now, that doesn't always take that long with a polymer, but let's take a little look at the next slide, which shows us what we can do without having to hold it manually.

So these are bending jigs.

Now, bending jigs is one of our key words today.

And the way that this bending jig works is it holds the heated polymer in the desired shape whilst it cools.

So it stops you having to hold it and try and get the same angle each time.

Therefore, if you are creating lots of identical products, you can get exactly the same angle every time with every product you make because it just takes the shape of the bending jig, it's great.

Now Jun says, "My teacher used line bending to manufacture multiple test tube holders during COVID testing." Now, these were actually what I made during COVID for my SLT when they were doing lots of COVID testing.

You might remember that yourselves.

Now, what I did was I laser-cut all of these shapes.

I made myself a little bending jig, just out a bit of scrap timber.

And then I bent it using the line bender and bent it around this jig.

And that jig held it in place so that every single one of those was identical.

What a treat.

A living hinge allows a polymer to bend by using a laser-cut pattern that creates a flexibility in the material.

So take a little look at the picture on the left.

If you look very, very closely, perhaps you might have to come a little bit closer so you can see it, there are lots and lots of little parallel laser-cut lines.

And the positioning of those lines allows the acrylic to bend without it snapping, they have to be very, very carefully placed.

So the next picture shows how that laser-cut pattern can then create that flexibility.

And it's great if you want to be able to get acrylic to go around a bend or around a shape.

And here's one of my students, they were actually creating something that allowed dried cat food to be easily dispensed.

So this was one of the parts that this young student had, and she wanted to wrap that acrylic around the shape.

So she experimented using living hinges and it worked beautifully.

Time for a quick check-in.

Which of the following is a bending jig? Is it A, B, or C? Have a little think, come back to me when you've got an answer.

Well done if you got A.

A is a bending jig.

So after perhaps you have used the line bender, you could then pop your polymer into a bending jig to allow it to cool into that shape.

B, you can see as a former.

And lastly, C, you can see is a mould because it's two parts.

Vacuum forming is a deforming process where a heated thermoplastic sheet is softened and then pulled tightly over a former using suction to form a desired shape.

Now, take a little look at the picture in the bottom right.

That is the whole entire vacuum-forming machine.

Now, if we zoom into that top part, into the top picture, you will see the GIF where vacuum forming is actually happening.

So there are two former in there, the polymer is heated up, then the air is sucked out so that the polymer takes the shape of that former.

Now, these have been made by hand and what I absolutely love about vacuum forming is that you can use loads and loads of different things to create different shapes and different details.

So I love using, say, buttons, and little building bricks.

And then my favourite has to be using plasticine, 'cause plasticine is great, you can mould it into whatever shape you like.

But the vacuum forming takes the shape of that plasticine.

It works really, really great.

Now, what that GIF is actually creating is a project that my students do.

Now, my students make desk tidies by creating their own formers, adding whatever texture they want.

be that plasticine, be that buttons, be that building bricks, and then vacuum forming over the top of that.

It works a wonder.

You can also use it for different purposes too.

So one of my GCSE students decided he would make his own mould.

So what he did was he made his former, in fact, he laser-cut his former.

He then used vacuum forming to create, see the green part in the middle, so vacuum forming created that to create his own mould, which then he poured a liquid silicon into, which was a part for his project.

It worked beautifully, but it wouldn't have been possible, he wouldn't have been able to make that exact shape out of the silicon unless he'd made his own mould using vacuum forming.

What a great idea.

You may be asked to draw out the vacuum forming process.

So let's take a little look at how we could draw it out.

First step, the former, which is the little purple shape, is placed in the bottom of the vacuum former.

The polymer sheet is then put on top and is heated up until it becomes flexible.

So then once the polymer sheet becomes flexible, the former is moved up into the heated flexible polymer sheet.

The air is then sucked out, and you can see that by the blue arrows.

And that means that the thermo polymer takes the shape of the former.

And lastly, the hollow product is produced.

Time for a check-in.

Which deforming process represents press moulding.

Is it A, is it B, or is it C? Have a think, come back to me when you've got a great idea.

Well done if you got C.

A is line bending, B is vacuum forming, and C, finally, is our press moulding.

With small-scale deforming processes like those that you might do in a workshop, there are benefits and limitations.

So let's take a little look at some of the benefits.

It's often low cost and easy to set up.

You've heard me talk about some of those formers and some of those moulds that we've made out of scrap timber.

So it can be quite low cost.

It's good for one-off prototype pieces or perhaps when you are experimenting to create a one-off piece.

And it can achieve detailed and bespoke shapes like the vacuum forming.

If you put bits and pieces on top of it, it will take the shape of whatever you put on, be that buttons or coins.

Let's take a little look at the limitations.

It can be time-consuming compared to industrial methods.

It often requires skill and patience.

You need to know all the ins and outs about that machine.

And sometimes it can limit us in size too.

'Cause quite often in a school workshop, we only have machines of a certain size, and not massive, like an automated process.

Which of the following is a limitation of a small-scale deforming process? A: time consuming, B: can achieve bespoke shapes, C: low cost, or D: good for prototypes? Have a good think, come back to me when you've got an answer.

Well done if you got time-consuming.

A limitation of small-scale deforming processes can be that it's very time-consuming because you need to get to know that machine in and out, and you have to sometimes make individual moulds or formers per process.

On to task A.

Part one, I'd like you to explain what is meant by a deforming process in polymer manufacturing.

Part two, draw a diagram to describe the deforming process, vacuum forming.

Part three, what is the purpose of a bending jig when using a line bender? And lastly, part four, give two benefits and two limitations of small-scale polymer deforming processes.

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

Part one, explain what is meant by a deforming process in polymer manufacturing.

A deforming process changes the shape of the polymer without cutting away any material.

It uses force and heat to bend or shape the polymer into a new form.

Part two, draw a diagram to describe the deforming process, vacuum forming.

So firstly, the former is placed in the bottom of the vacuum former.

The polymer sheet is then heated.

And once it's been heated, the polymer sheet becomes flexible and the former is moved up into the flexible heated polymer.

The air is then sucked out so that the heated polymer takes the shape of the former, which lastly leaves a hollow product.

Part three, what is the purpose of a bending jig when using a line bender? So a bending jig holds the heated polymer in shape whilst it cools, helping create identical angles for multiple products.

And you might remember that little test tube holder that used a bending jig to make them all exactly the same.

Part four, give two benefits and two limitations of small-scale polymer deforming processes.

So benefits can be its low cost and easy to set up, and it's good for creating custom or prototype pieces.

Limitations: It can be time-consuming and often requires skill, and it's often limited to smaller or thinner polymer pieces.

Well done with those great answers.

On to learning cycle two, "Industrial deforming processes." Industrial polymer deforming processes are usually automated and used in large scale manufacturing.

So to increase speed: machines can work continuously and quickly with minimal downtime.

Accuracy: So CNC, standing for computer numerical control, so CNC machine systems produce highly consistent forms and moulds.

Consistency: every product matches the design exactly, which is ideal for higher volume production.

Quick check in, what is one key benefit of using industrial deforming processes over small scale ones? Is it A: they require more human input, B: they provide faster and more consistent results, C: they use less electricity, or D: they are more random in shape? Have a little think.

Come back to me when you've got a great idea.

Well done done if you've got B.

One benefit or a key benefit of using industrial deforming processes is that they provide faster and more consistent results than small-scale ones.

Thermoforming is the industrial version of vacuum forming.

It works in exactly the same way, but it is automated, and more than one product is produced at a time.

Formers are usually CNC-manufactured from durable metal so that they can be reused again and again.

Thermoforming is used to produce yoghourt pots just like that image that we saw at the start of this lesson, and blister packs for pills.

Vacuum pressing is a way to shape and harden carbon fibre, otherwise known as CRF.

And it uses air pressure.

It helps make parts that are strong, even lightweight and smooth whilst removing air bubbles.

It is often used when manufacturing bike frames, car panels, or sports equipment.

And you can see in the image, this is actually one of my neighbor's cars, and you can see the CRF there.

It goes beautifully into that shape of the car part.

Let's take a little look at the stages of vacuum pressing.

So first of all, layers of CRF are placed over a former, and the resin is applied.

This is then placed in a sealed vacuum bag that is attached to a pump.

The pump sucks the air out forcing the CRF against the former.

It is left to harden or cure often with heat.

Quick check in.

What is the purpose of a vacuum bag in CRF deforming? Is it A: to clean the surface of the polymer, B: to keep the polymer warm, C: to remove air bubbles, or D: to apply even pressure drawing shaping? Have a little think, come back to me when you've got a good answer.

Well done If you've got C and D.

The purpose of a vacuum bag in CRF deforming is to remove the air bubbles, but to also apply even pressure during shaping.

Compression moulding is an industrial deforming process used to shape thermosetting polymers.

Now, let's just pause there.

You can see I've put that word "thermosetting" in green.

And the reason I've done that is because this is the only process that we are going to talk about for thermosetting polymers.

Now, thermosetting polymers are those ones that we cannot keep reheating and reshaping.

Whereas all the other processes that we've looked at so far have been for thermo polymers that you can reheat and reshape.

So compression moulding is an industrial deforming process used to shape thermosetting polymers by placing a preheated material into a heated mould where it is compressed until it cures and hardens into the final shape.

So what products do we find? You'll find them looking around the room that you are in now.

So examples include electrical fittings such as light switches or plug sockets, saucepan handles, and then melamine plates and bowls.

Let's take a little look at how we could draw out compression moulding.

So first of all, the thermosetting polymer, which is the blue circle in this example, is inserted in between a mould, a two part mould.

The polymer then is compressed between those two sides of the mould using heat and the material is heated itself too.

Then the mould separates, and you can see there's a little pin that we call an ejector pin.

The ejector pin pushes up and releases out the product from the mould so that a product is produced.

Calendaring is a process where heated thermoplastic is passed through rollers to produce thin, flat sheets or films with a smooth, uniform finish.

Examples include shower curtains and plastic bags.

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

So the heated calendar rolls reduce the thickness of the polymer, and you can see the polymer is the black part.

You can see it going through the top of the red roller is it's quite thick, and all of a sudden, it's starting to get thinner and thinner.

And it moves down to those three small rollers.

Now, these are the embossing rollers, which can add any required texture or can make it really, really smooth.

It's then passed through cooling rollers, which fix the polymer with the particular thickness and the particular texture that is required.

And then the polymer then moves on to be wound up into the required individual lens.

Just like cling film, it might be rolled into one roll for cling film and then the next roll for cling film, and so on.

Time for a quick check-in.

Which deforming process is likely to be used to make this drying rack? Would you say A: calendaring, B: compression moulding, C: vacuum pressing, or D: thermoforming? Have a little think, come back to me when you've got an idea.

Well done if you've got D, it is thermoforming.

Now, let's remind ourselves, thermoforming is the industrial version of vacuum forming that we saw in the small-scale production.

Well done if got that right.

In industrial settings, formers, moulds, and bending jigs are often made from metal such as aluminium or steel.

Now, that's a bit of contrast in comparison to small-scale where we saw that we could make them out of scraps of timber, be that a bit of pine, be that a bit of MDF.

But no, in industrial settings they tend to be made out of metal, and there's several reasons for this.

Metal such as aluminium or steel tends to be strong with good compressive and tensile strength.

It's ideal for repeated use, you can make lots and lots of them by using the same mould former or bending jig.

It's often highly accurate using metal because it takes the exact shape, especially if it has been made using CNC.

As I've just put, formers and moulds are usually CNC machined, I was jumping ahead of the guns there, wasn't I? It is also durable.

So the metal can withstand the heat, the pressure, and the moisture, and keep its shape.

Whereas timber, quite often, will warp because of moisture, metal will not.

Time for a quick check-in.

Why are bending jigs and formers used in industry made from metal? Is it A: they provide strength and precision for repeat shaping, B: they are easier to shape, C: they are flexible, or D: they are recyclable.

Have a think, come back to me when you've got a great idea.

Well done if you've got A.

The reason they're often made from metal is that they provide strength and precision for repeat shaping so they can form absolutely loads of the same thing.

Task B, part one: Explain why industrial deforming processes are more suitable than small-scale methods for higher volume production.

Part two: Use diagrams to explain how compression moulding is used to deform thermosetting polymers.

And lastly, part three: compare the role of a former in vacuum forming, small-scale, and thermoforming, industrial scale.

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

Part one: Explain why industrial deforming processes are more suitable than small-scale methods for higher volume production.

So the use of machines and automation help to produce complex shapes quickly and consistently.

This ensures every product is identical, which is essential for higher volume production.

Part two: Use diagrams to explain how compression moulding is used to deform thermosetting polymers.

So first of all, the thermosetting polymer is inserted in between the mould.

The polymer is then compressed between the mould.

The mould then separates and the ejector pin releases the product away from the mould.

And lastly, the product is produced.

Well done if you got that right.

And part three: What is the role of a former in an industrial deforming process? So a former provides the shape that the polymer will form around, both in vacuum forming and in thermoforming.

They ensure that each piece of polymer is shaped consistently and accurately during the deforming process.

In industrial settings though, formers are usually made from metal because they are strong and keep their shape during repeated use, unlike perhaps the use of timbers in small-scale production.

This brings us to the end of our lesson today.

Let's summarise what we have found out.

Deforming involves using force to change the shape of a material.

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

And deforming materials on a larger scale requires different techniques, just like we have vacuum forming, small-scale, and thermoforming, industrial scale.

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

Take good care, bye bye bye.