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 today is, which wasting manufacturing processes are suitable for polymers in small-scale production and also in industrial manufacture? We're gonna explore this using lots of examples that I'm sure you'll be familiar with and some that you might not be.

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 wasting processes.

We have four keywords today: wasting, which is removing material to shape or size a product; small-scale production, which is when we're making one or a few products, using hand tools or basic machines like we do in a workshop.

We then have industrial, which is higher volume production, using machines for speed, accuracy, and consistency.

And lastly, we have CNC, which is an abbreviation of Computer Numerical Control.

Basically what that means is, it's computer controlled machining for precise cutting and shaping.

We have two learning cycles today.

Firstly, small-scale wasting processes, and then secondly, moving on to industrial wasting processes.

So let's start off with small-scale wasting processes.

A wasting process is a manufacturing method where material is removed to shape or finish a product, and you will have done this loads of times throughout your education.

It includes cutting, drilling, and sanding.

These processes are commonly used in both small-scale production, such as the workshop, and industrial settings.

In small-scale production, so we're talking about in school workshops now, we tend to use hand tools for control and precision, such as coping saws, and then power tools for speed and consistency, such as fretsaws, and I'm sure you might be familiar with a few of those.

Cutting tools are used as part of the wasting process to remove unwanted areas.

These small-scale production tools can be operated manually.

So we'll start off with the coping saw.

The coping saw, as you might know, has a thin blade that can be rotated easily to cut intricate shapes.

The blade can also be removed to cut internal shapes, and you can put in different blades according to what material you are trying to cut through.

We also have a craft knife.

Now a craft knife can be used with a safety rule to protect those fingers and a cutting mat to cut thin sheets of polymer, such as thin sheets of polypropylene.

Cutting tools are used to remove unwanted areas, as we've just seen with the coping saw and with the craft knife.

However, small-scale production tools can also be operated by power.

We have the fretsaw that can cut through sheet polymers such as acrylic or styrofoam.

And we also have a hot wire cutter that can use heat to cut through sheet polymers such as styrofoam.

And as I'm sure you're aware, you don't normally cut that quickly with a hot wire cutter, but I've speeded up that video so you can see it working.

Time for a quick check-in.

Which tool or machine would not be suitable for cutting sheet acrylic? We have A: the coping saw, B: the fretsaw, and C, the hot wire cutter.

Have a think.

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

Well done if you got the hot wire cutter.

That's really suitable for things like styrofoam, but definitely not suitable for sheet acrylic.

Drilling is also a wasting process that makes holes in a material.

Just have a little think now.

What kind of drilling machines or tools can you think of that you might have had experience with? Have a think.

Have a chat to the person next to me.

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

Okay, let's draw us back together.

Hopefully you might have thought of the manually operated hand drill that's used for precise, small holes.

You might have thought of the cordless power drill used for drilling holes and driving screws in.

And you might have also thought of the pillar drill or the bench drill.

So a pillar drill is fixed to a base and used to make straight, accurate holes.

Drill bits are cutting tools that attach to a drill to make holes in materials.

Have a little think, perhaps talk to the person next to you.

What type of drill bits are suitable for use with polymers? Have a think.

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

Okay, let's draw us back together.

You might have thought of twist drill bits for smaller holes.

You might have thought of Forstner bits that make flat-bottomed holes with smooth sides.

You might have thought of hole saws that create large circular holes.

And lastly, my favourite.

You might have thought of a cone drill.

Now, a cone drill if you've never seen one before, is a stepped drill bit.

And you can see those little steps going up.

Basically, the cone drill gradually cuts larger holes in polymers, and the way it does it is it kind of scrapes rather than twists, and basically it reduces the risk of cracking or melting when you drill through a polymer.

They're a great part to use if you spend ages on a piece and you're really worried about cracking it.

Quick check-in.

Which drill bit is least likely to crack a polymer? A: the twist, B: a Forstner or C: a cone.

Have a little think, come back to me when you've got an answer.

Well done if you got the cone.

The cone drill bit is a lot less likely to crack a polymer.

So it's a great choice when drilling polymers.

Filing and abrading is a wasting process that involves removing material to shape or smooth a piece.

I'm sure you are all probably familiar with hand files.

So hand files are tools with a metal surface covered in tiny little teeth.

It's used to smooth or shape materials such as wood, metal or polymers by rubbing it back and forth.

Now hand files come in a range of different sizes and profiles, so for example, triangular or round.

Now some of the smaller rounds we tend to call "rats tails" files.

We also have flat files and we have half round files too.

So depending on what shape you're trying to file depends on what shape and file you use.

There are different techniques when it comes to filing.

So cross filing as you can see in the little gif, is when you move the file diagonally across the material using a back and forth motion to remove material quickly and shape the surface.

Once you've done that, you can then move on to draw filing.

Now draw filing is when you hold the file with both hands and you pull it along the length of the material, which creates a much smoother and more even finish than cross filing.

So you start with cross filing and then you move to draw filing.

Sanding can also be done with power tools and machinery.

This speeds up the wasting process, especially if there is a lot of material to remove.

So a power sander is often used in small-scale production.

The abrasive pads are available in different grades and we'll talk about grades in a few slides time.

You must though of course, be careful and have extraction with that.

We also have a belt sander, which can remove more material in a shorter amount of time.

But again, be careful not to use it for large chunks because otherwise, you will wear down the belt too quickly.

Wet and dry abrasive paper can be used either wet or dry, just as it says on the tin.

So you can put a little bit of water on it and you can see here it is being rubbed along the surface and this gives it a beautiful, beautiful finish.

Now using wet and dry with water also reduces both dust and heat, which has to be a positive.

And I always think the surface finish is even smoother when you've used it wet too.

Abrasive paper, such as wet and dry like we've just seen, can be used to smooth, shine or clean surfaces.

It comes in different grades, which we commonly call "grits," which tell you how rough or smooth the paper is.

The number corresponds to the size of the abrasive grit on the paper.

So if it's a low number, that abrasive grit is quite big.

There's not so much of it because the pieces are big.

Whereas if we move all the way up to 2000 and you can actually get numbers which are higher than 2000 too, that is really, really extra fine because there are so many bits of that on the pay bed, teeny, teeny, teeny tiny bits.

Therefore, low-number grades are rough and remove a lot of material quickly, while medium grades are for smoothing things out.

And high-number grades are used for polishing, so it's quite normal to start off with a low grit, then move to a middle grit, medium grit, and then move to a very high, extra-fine grit for that final real smooth finish.

Next time you're using some abrasive paper, have a little look at what number grit is on the back of that paper.

After using abrasive paper, polishing can create an even shinier and smoother final finish.

So we have things such as the buffer machine.

Buffer machine is a rotating polishing tool used to quickly smooth and shine the surface of polymers.

But then we also have, by hand, we have a fine abrasive polish that can be used to remove any scratches and give a shiny finish.

And you often, just like the gif, you often put it on a little bit of fabric and then rub that into the surface to make it ultra, ultra shiny.

Quick check-in.

Which grade of abrasive paper is smoothest and will give a fine finish? Is it A: 150 grit, B: 800 grit, or C: 600 grit? Have a think.

Talk to the person next to you.

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

Well done.

If you've got B.

B is the highest number out of them all, therefore it will give the finest finish out of all of those three options.

Well done if you got that right.

On to Task A.

Part one, define the term "wasting process" in the context of manufacturing.

Part two, explain how to create a shiny and smooth finish on a polymer during small-scale production.

Part three, explain one advantage and one disadvantage of using a power tool instead of a hand tool.

And lastly, part four, explain why both hand and power tools are used in small-scale production.

Good luck.

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

Part one, I asked you to define the term "wasting process" in the context of manufacturing.

So a wasting process is a method of shaping or finishing a material by removing parts of it, such as cutting, drilling or sanding.

Part two, I asked you to explain how to create a shiny and smooth finish on a polymer during small-scale production.

So your answers could include: cross filing, followed by draw filing will create a smooth finish.

To make it smoother, you can then use wet and dry abrasive paper, increasing the number of grit each time.

And then to ensure a shine, a buffer could be used or a fine abrasive polish.

Part three, I asked you to explain one advantage and one disadvantage of using a power tool instead of a hand tool.

Answers could include: power tools are faster and require less manual effort.

However, they can be more dangerous and require a power source.

Part four, I asked you to explain why both hand and power tools are used in small-scale production.

Answers could include: Hand and power tools are both used in small-scale production because they each have different strengths.

Hand tools allow for greater control, precision and detail, whilst power tools help speed up tasks, cut through material more efficiently and reduce physical effort.

Well done with all your efforts on these questions.

On to learning cycle two: Industrial wasting processes.

Industrial wasting processes require more heavy-duty machinery.

This is because speed, accuracy and consistency are required for larger production runs.

CNC, one of our keywords today, stands for Computer Numerical Control, which means that some machinery can be controlled by a computer using code.

CNC machinery is often used in industry because it can cut complex and precise shapes repeatedly with minimal human intervention.

I hope that many of you are lucky enough to have a laser cutter in your school, and if you are, I hope you've had the chance to use them.

You probably if you have designed something using CAD, using a specific CAD programme that your school has, to create your design.

Perhaps you've used colours to show which bit you want it to cut and perhaps which bit you want it to engrave.

So once it gets sent to the laser cutter to the cam.

Now the CAM, standing for Computer Aiding Manufacture, is the laser cutter.

So the laser cutting polymers uses a focused laser beam to melt polymer materials, creating precise cuts, but it can sometimes cause melting or discoloration around the edges.

So you have to be careful what power settings you use.

Changing the power of the beam can engrave text or images.

Hence why sometimes it's important to use different colours when you're designing in CAD.

Laser cutting is often used in industry for signs and display stands.

Vinyl cutting on a CNC plotter uses a sharp blade to precisely cut thin polymer films like vinyl sheets, without heat, making it ideal for stickers and decorations.

So if we look at the machine there, if we zoom in there, you will be able to see the sharp blades.

So you must make sure your fingers go nowhere near that.

This is a large CNC plotter, but you might perhaps at your school have small vinyl cutters.

We do at mine and it's great for decoration of projects.

So vinyl cutters are available in a range of sizes, used in both small-scale and industrial manufacturing.

Careful placement, otherwise known as nesting, of designs, reduces waste between products.

So look at the two diagrams that I have put on here.

Take a minute now and look at the space between all of those shapes.

Which one of these reduces the amount of waste? Look carefully, get yourself a reason.

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

Okay, fantastic.

Hopefully that has given you the chance to really carefully look at the space between the circles.

And if you can see in grey, I've highlighted it on both of them.

The large amount of grey space on the left in comparison to the small amount of grey space on the right.

Placing them like the second diagram on the right basically reduces the amount of waste, which means if you think about an incredibly large sheet, be that in a laser cutter or be that on a CNC plotter, it will reduce the amount of waste overall.

And if you look carefully at the bottom, you'll see there's a whole line of spare material at the bottom.

Put that on a much larger scale and we fit a lot more shapes into a certain area which reduces waste and reduces the amount of money needing to be spent on materials.

So I've put it's important to nest designs, to maximise material use, reduce waste, and increase cutting efficiency.

Time for a quick check-in.

Which attempt at nesting reduces the most amount of waste? Is it A, is it B, or is it C? So you're looking, the green triangle is the shape being cut from the white material.

Which one reduces the most amount of waste? Come back to me when you've got an idea.

Okay, well done if you got B.

If you look on A, there are only four triangles cut out.

If you look at B, there are one, two, three, four, five, six, seven, eight triangles cut out because they've been flipped up for nesting.

Let's take a look at C.

We've got one, two, three, four, five, six, therefore B wins with eight triangles cut out.

The better use of space, the better the nesting, the less waste produced.

And try and think about that when you're doing your own practicals in your subject so that you reduce the amount of waste that you produce too, which leaves more for other people to use as well.

Drilling large numbers of holes that are accurate is important when manufacturing products in bulk, for example, acrylic signs.

CNC drills can create many holes quickly and precisely by following a computer programme to match a digital design.

This reduces human error and guarantees consistency across batches.

And if you take a little look at the picture, rows of precise holes like these are common in acrylic signs.

It means that all placed exactly the right spot, which is great when perhaps you're installing a big acrylic sign in a particular space.

CNC routing and milling are used in industry to create complex shapes that will be difficult or time-intensive to produce by hand.

Both machines follow computer instructions to move their cutting tool accurately along the X, Y, and Z axes, to cut and shape the material.

CNC routers are used for softer materials and usually operate across a wider surface area.

CNC milling is used for harder materials and offers more precision and depth along the Z-axis.

The tooling can be changed on CNC routers, depending on the angle required.

So you can have tools which are straight, producing nice, straight cuts, believe it or not.

And then you can have tools which are bevelled, creating bevelled cuts, which are at an angle.

In schools, it's quite common that high density foam prototypes are manufactured using CNC routers in schools.

And these are some of the models that we produce at my school using the CNC routers.

Die cutting polymers is an industrial process that uses a shaped blade that we call a die to quickly and precisely cut polymer sheets or films into specific shapes.

It can be used to cut hexagons and pentagons for footballs.

So here's a little diagram.

If I zoom in, there is the die.

That's the shape that's about to be cut.

Dies allow multiple identical shapes to be cut.

Therefore it can cut all of the pentagons required for footballs before they are stitched together and it ensures that they are all exactly the same as each other.

Water jet cutting is a CNC industrial wasting process often used to cut display panels.

Did you notice how that sentence has three keywords in it? Wow! Anyway, it uses a high-pressure stream of water, sometimes mixed with abrasive particles to precisely cut polymer materials without causing heat damage.

Pretty cool, hey? Time for a quick check-in.

Which of the following industrial processes melts polymers when wasting? A: die cutting, B: laser cutting, C: water jet cutting, or D: vinyl cutting.

Have a think.

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

Well done if you got laser cutting.

A laser cutter melts the polymer when it is wasting, unlike the other processes.

On to Task B.

Part one, I'd like you to explain one advantage of using CNC machines in industrial production.

Part two, I'd like you to name two polymer industrial wasting processes and describe their main function.

Part three, why are industrial processes more suitable for higher volume production? And then lastly, compare a small-scale production process to its industrial counterpart.

Give one example and explain the main difference.

Good luck.

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

Part one, I asked you to explain one advantage of using CNC machines in industrial production.

So you may have said CNC machines can cut and shape materials with high precision and consistency, allowing large batches of identical components to be manufactured efficiently.

Part two, I asked you to name two polymer industrial wasting processes and describe their main function.

You may have chosen CNC routers, which cut and shape sheet material according to a computer programme, and you may have picked die cutting, which uses a shaped blade, otherwise known as a die, to quickly and precisely cut polymer sheets or films into specific shapes.

And we looked at the football pentagons as the example there.

Part three, why are industrial processes more suitable for higher volume production? You may have said industrial machines, especially CNC, can produce large numbers of parts quickly, accurately, and with very little variation between them, which is ideal for higher volume production.

Part four, compare a small-scale production process to its industrial counterpart.

Give one example and explain the main difference.

You may have compared a hand drill to a CNC drill.

So a hand drill is manually operated and less accurate.

Whilst a CNC drill is computer-controlled, faster, more precise, and can produce large batches efficiently.

Well done with all of your efforts on these.

This brings us to the end of our lesson today.

Let's summarise what we have found out.

Wasting involves removing material to shape or size a product.

Tools and small machines remove material in a small-scale production.

CNC stands for Computer Numerical Control, which means that some machinery can be controlled by a computer.

Larger machines remove material quickly, more accurately and consistently at scale.

Well done with all of your hard work today.

I hope to see you in another lesson soon.

Take good care.

Bye bye bye!.