Lesson video

Hello.

Thank you for joining me for design and technology lesson.

My name is Mrs. Conway and I will be guiding you through your learning today.

So today's lesson outcome is, I can finish the surface of a product to a high standard.

And these are our keywords, self-finishing, additive, and finishing.

I'll go through each one of these in more detail as we work through the lesson.

So the first thing we're going to look at then is finishing polymers.

The manufacturing process affects how a polymer is finished.

Reforming processes are usually self-finishing, which means they do not require additional processes after being manufactured, such as an example here of a polymer building block.

The quality of the finish of injection molded building blocks is determined by the quality of the mold.

And here you can see a building block mold.

Different polymer manufacturing processes, such as wasting or fabrication, require additional finishing.

And these include polishing or buffing, painting, decals, or printing.

Quick question for you then.

Which polymer processes are self-finishing? A, wasting, B, fabricating, C, deforming, or D, reforming? Pause the video here just to think about your answer.

And the correct answer was reforming.

So reforming polymer processes are self-finishing.

After filing and wet and dry, polishing using abrasive compounds can create a shiny and smooth final finish.

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

Also, a fine abrasive polish can be used to remove any scratches and give it a really shiny finish.

Paint can be applied to polymers as well, so water-based paints will not adhere to polymers.

Model planes or toy characters are often painted using acrylic paint.

And here's an example of a toy painted using acrylic paint.

Pad printing is an industrial finishing method used to transfer images onto products that may not have a flat surface.

So here's an example.

The image is etched into a printing plate.

The ink then fills the etched design.

And the soft silicon pad presses onto the plate to pick up the ink.

And then the pad presses onto the object, transferring the image.

Quick question for you then.

Which polymer finishing technique uses abrasive compounds? Pause the video here just to take a moment to think about your answer.

And the correct answer was polishing or buffing.

Well done if you got that right.

Vinyl decals can be cut or printed.

Vinyl cutting on a CNC plotter uses a sharp blade to precisely cut material.

Here's an example of a CNC plotter, and there is the sharp blade picked out inside the circle.

Vinyl decals can be used on things such as vehicles, like in the example just there.

Printing can also be used to enhance the aesthetics of polymers.

Screen printing is where ink is transferred onto the polymer through a stencil.

And heat press printing transfers a printed design on sublimation printed paper with special ink to the polymer using heat.

Okay, it's going to be over to you now to have a go at a few tasks.

First thing I'd like you to do then, for each of the examples described, I'd like you to explain which polymer finishing process is suitable and why.

A, sheet acrylic cut to using a coping saw and then filed, and B, injection molded milk bottle top.

And the second task, I'd like you using notes and sketches, describe the pad printing process when used to add images to a recycling bin.

Okay, pause the video here to have a go at these two tasks, and good luck.

Okay, let's look at the first task then.

I asked you to consider a polymer finishing process for sheet acrylic cut using a coping saw and then filed.

Here's the example answer.

"The most suitable method to finish the edge of the cut sheet acrylic would be to file, then use wet and dry abrasive papers.

Then, apply polish with a cloth and buff it with a cloth mop on a buffing machine." Just check your answer against the example and make sure that you've included all those key bits of detail.

The other I asked you to look at then was injection molded milk bottle top, and the example answer reads, "Injection molding has been used.

This is a reforming process and therefore self-finishing.

The bottle top would not require any further finishing." That was a bit of a trick question there for you to consider.

Check you've got the key points there and you've got that right.

The next thing I asked you to do was using notes and sketches, explain the pad printing process when used to add images to a recycling bin.

So here's the example.

Compare your diagrams and see that you've included each key stage.

So the first one was that the image is etched onto a printing plate.

Then the ink fills the etch design and a soft silicon pad presses onto the plate to pick up the ink.

The pad then presses onto the object, transferring the image.

And once the ink is dry, the product finishing is complete.

So next, we're going to look at additives.

In industry, polymer products can be enhanced or modified by adding an additive.

An additive is a substance added to something else to improve or alter it.

Polymers often modified with additives to improve color, flexibility, UV resistance, fire resistance, and also anti-static.

Adding a lubricant, such as wax, to a molten polymer means the polymer flows more easily into the mold, and this allows for more complex shapes to be made quickly, which makes the process more efficient.

Fillers can be used to reduce the amount of polymer needed in each product.

Common fillers include wood flour, so a very fine sawdust, and also chalk.

Chalk is less expensive and therefore reduces the overall cost.

Fillers can sometimes improve strength as well.

Flame retardants reduce the likelihood of a fire starting or spreading.

They are used in items that are close to heat or electrical sources, such as plug sockets.

Urea formaldehyde plug sockets contain flame retardant additives.

What is the purpose of a flame retardant additive? A, to improve the aesthetics, B, to reduce the likelihood of a fire starting or spreading, or C, to reduce the cost? Pause the video here.

Just take a moment to think about your answer.

And the correct answer was B.

So the purpose of a flame retardant additive is to reduce the likelihood of a fire starting or spreading.

Color pigments can be added to enhance the aesthetic qualities of a polymer.

They are usually powdered and combined with the molten polymer before being processed.

Another quick check for understanding then.

I'd like you to match the polymer additive to the reason for its use.

So you have color pigment, wood flour, and wax.

And possible reasons, you have reduced costs, increase process efficiency, and enhance aesthetics.

Pause the video here to match these together.

Let's look at the correct answers then.

Wood flour matches with reduces the costs.

Color pigment works to enhance aesthetics.

And wax can increase the process efficiency.

Well done if you've got all of those right.

3D printing filament is available in many different colors.

Phosphorescent pigments, for example, are added to create glow in the dark filament.

Wood filament is 70% PLA and 30% wood dust.

It looks like a timber, but can be formed like a polymer.

Degradation is when something degrades or breaks down.

Some polymer products are enhanced with additives to slow this process down, for example, to increase UV resistance in uPVC window frames.

Polymers used for food packaging and single-use carrier bags often include additives that speed up degradation.

Biodegradable additives degrade quickly and do not contribute to landfill waste.

Okay, key tests for you then.

Firstly, I'd like you to explain what an additive is.

Then I'd like you to state five reasons why additives are used in the manufacture of polymers.

I'd then like you to give three different examples of polymer products where additives are used and explain the specific purposes.

And lastly, I'd like you to explain how you will prepare and finish your specific product.

Okay, pause the video here to have a think about these tasks, and good luck.

Right, let's take each one of these in turn.

So the first thing I asked you to do was to explain what an additive is.

The example answer reads, "An additive is a substance added to something else to improve or alter it." Just check you've got that right.

I then asked you to state five reasons additives are used in the manufacturer of polymers.

To improve or change color, to improve flexibility, to improve UV resistance, to improve fire resistance, and to increase anti-static properties.

Just check you've managed to get all of those.

I then ask you to give three different examples of polymer products where additives are used and explain their specific purposes.

Your answer may vary slightly to the example, but just check you've got the key points.

And if you are unsure about yours, you can always ask your teacher or someone else in the class to check it.

So here's one example.

"Plug sockets have flame retardants added, which reduces the risk of a fire starting or spreading.

uPVC window frames have UV stabilizers added, which slows down the degradation process and makes the windows last longer." And the last example, "Single use carry bags have biodegradable additives added, which increases the speed that they degrade, which means less waste in landfill sites." And the last thing I asked you to do was to explain how you will prepare and finish your product.

We can look at Alex's example just to give us an idea of an example answer.

So Alex has explained, "I'm using fused filament fabrication 3D printing to manufacture the main body.

I can adjust the settings to increase the quality of the final prototype print.

The laser cut parts will be self-finished, eliminating the need for further finishing.

Any acrylic components that need finishing can be filed and then smoothed using wet and dry abrasive papers.

Polishing using abrasive compounds can create a shiny and smooth final finish." Your answer's going to be different to Alex's here, but have you included everything that you possibly could use to prepare and finish your product? Right, let's summarize today's lesson then.

Today we've been looking at surface treatments and finishes.

Now, how a polymer is manufactured affects how it is finished.

Polymers can be polished, painted, printed on, have decals attached, or can be self-finishing.

The quality of the surface finish when reforming polymers is determined by the quality of the mold.

Additives can be used to improve or alter polymers.

They can improve the production efficiency, product function, aesthetics, or also the degradability.

Well done for all of your hard work today.

Thank you so much for joining me, and I will see you soon.