Lesson video

Hello there, my name is Mrs. Darmi.

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

Now the big question today is what are the options when we come to finishing polymers? There are loads of different ones, so we're going to explore them together.

Hard hats on, let's get cracking.

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

We have four key words today.

Finishing, which is a process that adds surface treatment to improve how a material looks, feels, or performs. Aesthetics, which is how the product looks, including color, texture, and style or theme.

Function, which is what a product should do to be successful.

And lastly, surface preparation, which is where we are getting a material ready for a surface treatment.

We have two learning cycles today, small-scale finishing processes, and then moving on to industrial finishing processes.

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

Finishing for many materials is the final stage of manufacture, however for polymers, finishing also happens throughout manufacture.

It serves three main purposes.

Protection, so from scratches, chemical damage, UV light, and general wear.

Function, perhaps alters the flexibility or the durability of a polymer.

And lastly, aesthetics, enhancing the appearance, for example, by polishing, painting, or adding textures or text.

Finishing for protection and function includes the incorporation of something called additives.

Now those additives are added to the polymer at the material's processing stage, which will then influence the choice when purchasing materials.

Additives include stabilizers, pigments, and plasticizers.

I'm gonna look at those in a little bit more detail on our next slide.

Stabilizers help to protect against UV damage so that polymers do not turn brittle when outside.

So for example, uPVC window frames obviously get loads of UV rays on them every day.

It's the same with lots of polymer children's toys that tend to be outside.

Some of them tend to fade or go brittle.

So adding stabilizers helps to stop that process and keep them looking new and keep them being usable.

Pigments.

Now pigments add color, and therefore they've reduced the need for painting.

Quite often you don't need to paint or spray paint polymers because of the pigment added at the material's processing stage.

And a great example of that is obviously children's toys, such as those little learning building bricks that are available in lots of different colors due to the pigments.

We also have plasticizers.

Now, plasticizers influence the function by creating flexibility.

So for example, rigid PVC is often used in drain pipes, and you can see that in the picture on the very bottom left.

However, if you add a plasticizer to PVC, it makes the PVC go flexible.

So for example, hose pipes, hose pipes, as you know, you can bend them around a corner, you can bend them around a wall because they've got that flex.

Yet they are the same material as a drain pipe, but because of the addition of the plasticizer, they become flexible.

What a great idea.

Time for a quick check-in.

I would like you to match the additive to its definition.

So the definitions are A, prevent UV damage, B, creates a flexible polymer, or C, provides color.

And the additives, number one, we have plasticizer, number two, we have pigment, and lastly, number three, we have stabilizer.

Have a go at creating the matches and come back to me when you've got some solutions.

Okay, let's check your answers against mine.

So A, prevents UV damage, matches nicely with stabilizer.

B, creates a flexible polymer, matches beautifully with number one, plasticizer.

Remember the hose pipe? And lastly, C, provides color, that matches with number two, which is pigment.

While done, folks.

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

So you might use a buffer machine.

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

You might also use a fine abrasive polish to remove any scratches and give a shiny finish.

And you can see it's being decanted by putting it onto a cloth.

And you can see that's being rubbed along the edge of the polymer to take out those final scratches and give a beautiful shiny finish.

Flame polishing is a finishing process used on thermoplastics such as acrylic signs.

So how does it work? A controlled flame is passed over the surface melting just the outer layer.

This removes small scratches and creates a smooth, clear, glossy finish.

And you can see those steps in the pictures below.

Time for a quick check-in.

Which final finishing methods are suitable for the edges of acrylic? We have A, flame polishing, B, pigment, C, plasticizer, or D, buffer machine.

Have a think, make choices.

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

Well done if you've got A and D.

Flame polishing and the buffer machine are great as final finishing methods for the edges of acrylic, whereas pigment and plasticizers are both examples of additives that would've been added to the raw material at the material's processing stage.

Vinyl cutting on a CNC plotter uses a sharp blade to precisely cut thin polymer sheets, like vinyl sheets, without heat, which is ideal for making aesthetic decorations, just like the Oak symbol that I cut out in the picture on the left.

So the picture on the right is a CNC plotter.

And you can see we have zoomed into the sharp blade.

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

Let's take a closer look at how they work.

Here's a small-scale vinyl cutter that is in my school.

So the vinyl cutter cuts out the pattern required, and at the minute, it's cutting out the Oak symbol.

We then use something called low tack tape.

Now low tack tape is a little bit like sticky tape, but it's a lot, lot, lot less sticky.

And that is used to remove the cut vinyl.

And you can see me lifting the Oak symbol there.

That same low tack is then used to apply the vinyl to the product.

And you can see I've stuck it on there and I'm slowly peeling it off to reveal the sticker.

However, before that, you need to remember surface preparation.

Now surface preparation is one of our keywords today, and it's all about preparing that surface before you apply the finish.

So the best thing to do on acrylic is to make sure any grease or oil or fingerprints are being removed so that that vinyl sticks beautifully.

A sublimation printer and heat press can transfer vibrant, permanent aesthetics onto specially coated polymers.

There's your surface preparation.

It works by turning solid dye into a gas that bonds with the surface.

Let's take a closer look.

First of all, you need sublimation printed paper, and you need to print that from a special sublimation printer with special sublimation inks.

You then got to allow your heat press to warm up to the desired temperature.

You then place your acrylic with your sublimation printer face down on top of it, and then close the lid to apply the heat.

And you've got to wait a set amount of time, which is quite often only a few seconds depending on your machine.

And what is left? You are left when you open up the machine and peel off that sublimation paper, you are left with a beautifully decorated product.

And in this instance, a beautifully decorated Oak symbol.

Isn't it great? Let's take a little look at a comparison between vinyl cutting and sublimation.

So vinyl cutters, surface preparation, the material must be cleaned and degreased.

Benefits, it's quick and easy to apply, but it's also removable if you did want to take it off.

Limitations, the edges can lift or peel over time, and it's not suitable for outside use.

I made this mistake.

I put a lovely cut symbol, well some lovely cut text actually onto my recycling bin to make sure that my husband got the right bin when he was using them, but unfortunately it started to peel off now.

We're also limited with the detail that we can get with vinyl cutting.

So sublimation, surface preparation, a polyester coating is applied.

Benefits, it's permanent, it's high quality and detailed images, it's scratch resistant, durable, and can be used outside.

Limitations, it is limited to light colored surfaces.

It doesn't work so well on dark surfaces.

And obviously it requires heat.

It's important to think about these benefits, limitations, and surface preparation when you are choosing which aesthetic finishing process to use.

Polymers can be painted, however, this is often avoided by using pigments.

Do you remember, pigments was a way of adding color as an additive at the material's processing stage.

So it can be avoided by using pigments, vinyl cutting, or sublimation.

To paint a polymer though, if you really want to, you can use acrylic paints or spray paints, but you need a lot of surface preparation first to avoid the paint peeling or flaking.

So what do we need to do? We need to clean the polymer to remove the dust, grease, or oils, we need to sand it lightly to create a surface the paint can actually grip to, and it's often useful to prime it with a polymer-compatible primer for better adhesion.

If you are going to paint or spray paint a polymer, it's a great idea to use a spraying booth to remove those harmful fumes.

When finishing polymers, it is always important to consider the following health and safety aspects.

Ventilation.

Some finishes release fumes called VOCs.

This stands for volatile organic compounds.

It's also good to consider PPE, which stands for personal protective equipment.

Things such as gloves, goggles, or masks may be needed.

Storage too.

Some finishes are flammable and require adequate storage, and your school is very likely to have a special cupboard to store liquids or paints or sprays such as these.

Time for a quick check-in.

What does PPE stand for? Is it A, personalized protective equipment, B, personal protective equipment, C, preventative protective equipment, or D, personal preventive equipment? You might need to read back through those yourselves.

Okay, have a think, come back to me when you've worked it out.

Well done if you got B.

PPE stands for personal protective equipment.

Onto task A, part one, I'd like you to explain one reason why a polymer may need to be degreased before finishing.

Part two, name two additives that can be incorporated into polymers and explain their purpose.

Part three, a pupil wants to add a photo of their pet to their polymer project.

Recommend a suitable finish and justify your choice.

And lastly, part four, describe one method of applying a polymer finish and explain one health and safety consideration for this method.

Feel free to go back through some of those slides if you just need a quick refresh or a recap.

Good luck with your beautiful answers, and come back to me when you have formulated them.

Part one, I asked you to explain one reason why a polymer may need to be degreased before finishing.

You might have said when using a vinyl cutter, a polymer will need to be degreased so that when the vinyl is applied, it will stick well and be unlikely to peel off.

Part two, I asked you to name two additives that can be incorporated into polymers and explain their purpose.

You might have said pigments create the required color for the polymer, links beautifully into aesthetics.

You might have also said stabilizers prevent UV damage so that polymers do not turn brittle when outside.

And that links beautifully into function, such as uPVC window frames.

Part three, a student wants to add a photo of their pet to their polymer project.

Recommend a suitable finish and justify your choice.

You might have said an aesthetic design printed using a sublimation printer can be applied permanently to a polymer using a heat press.

This allows a vast array of color and detail to be achieved without the risk of it peeling off.

It's a great process, that one.

Part four, describe one method of applying a polymer finish and explain one health and safety consideration for this method.

You might have chosen spray paint.

Spray paints can produce harmful fumes.

Using an extraction booth and PPE can provide protection for the person applying the finish.

Well done with your wonderful answers.

Onto learning cycle two, industrial finishing processes.

Industrial finishing is the large scale application of finishes to polymer products during mass production.

These processes are often automated and are designed for high speed and volume, quality and consistency, and cost effectiveness by reducing human labor and reducing human error.

Industrial processes are efficient, but less flexible than hand-finishing.

In industry, finishing is integrated into the production line using conveyor systems. Items move through each finishing stage, such as cleaning and inspecting the product.

Automated machinery.

Automated machinery is programmed to complete a repetitive task and ensure consistency in application, such as coating machines that apply layers of coatings to improve various qualities.

And curing, UV or heat curing chambers dry finishes quickly.

Automation in industrial finishing ensures consistency so that you get quality across hundreds or thousands of units, speed, so that multiple items can be finished in seconds.

Precision, robotic arms can apply uniform coats to make sure it's really, really even.

And then waste reduction, controlled spraying reduces overspray.

Time for a quick check-in.

What is one main benefit of using automated machinery in polymer finishing? Is it A, they apply finishes with consistent quality, B, they apply finishes slower than by hand, C, they make polymers more durable, or D, they reduce the cost of raw materials? Have a think, make your decision, and come back to me when you've got an answer.

Well done if you got A.

A main benefit of using automated machinery and polymer finishes is that they apply finishes with consistent quality, so they'll all come out looking the same and exactly how you want them to.

If the manufacturing process requires injecting, the product will need degating.

Now degating is to remove the excess polymer left where it entered the mold.

And you can see this if I zoom in there, that is the little gate, that is where it has been injected, and that part will need degating, which means it needs to be removed.

If a two-part mold is used, deflashing may be needed or required to trim the excess polymer that seeps out at the mold join.

And you can see that I have labeled the flashing a bit at the top, a bit at the bottom.

That is the point where the two-part mold has joined, which then leaves our final product, which has been degated and deflashed and is ready to be sold.

Laura says, "I have seen deflashing with Play-Doh." Now Laura is exactly right, and I think you might be able to relate to this and relate the deflashing to the Play-Doh.

So let's take a little look.

First of all, you have a mold and you have your Play-Doh.

You then close the mold with the Play-Doh inside.

When you open it up, there's nearly always a little bit of excess Play-Doh, which is around the edges.

Now that nearly always happens because you can't get exactly the right amount of Play-Doh every single time.

Very unusual.

So when you open that mold, those little bits of excess Play-Doh is what needs to be deflashed.

So those little bits of excess we call flashing.

So deflashing them is removing that.

Now you also get a tiny, tiny bit around the edge too, which isn't quite so obvious as those big bits that we've just talked about.

But if you see the join, you can see exactly where that two-part mold joined by that little bit of excess flashing sticking out between.

Again, that part needs deflashing to make sure that the product is safe and of suitable quality.

Great example.

Thank you, Laura.

True or false? Degating removes the excess polymer that has slipped out between the sides of the mold.

Have a little think, make your decision, come back to me when you've made it.

Well done if you worked out that this statement is false, but why is it false? Well, degating removes the excess polymer from where it has been injected.

Whereas deflashing is what the statement is talking about.

Deflashing may be needed to trim excess polymer that seeps out at the mold join.

Laser engraving can be used in both small-scale and industrial finishing processes for aesthetics.

The power and speed of the laser beam can be adjusted to alter the depth of the engraving that is required.

And you can see in the gif and the images there, that is my laser cutter at school engraving our beautiful Oak symbol.

And the great thing about it is that it is permanent.

You cannot wipe it off, so it stays there permanently, which you can use for pictures, you can use for text, or you can use for patterns.

Overmolding is a process where one polymer is molded over another to create a single part with multiple materials or textures, such as a toothbrush.

And a toothbrush is the great example.

So we have the orange polypropylene for rigidity and durability, but then we have the white TPE, which is a flexible polymer used for soft, ergonomic, non-slip grip, which goes beautifully with the function with wet hands in a bathroom.

Texture, embossing, patterns and text can be included in the surface of a mold so that extra finishing processes are not required.

Whereas for other materials, such as timbers, more finishing processes would be required.

So if you take a little look at the mold, you can see the texture is inside the surface of that mold.

Therefore, when the product is released, it already has the finish applied, which is great for both function and aesthetics.

The ridges are great so that the bottle does not slip out of somebody's hand, but it also produces that aesthetic look to that bottle to make it individual to the brand too.

Pad printing is an industrial finishing method used to transfer images to larger products that may not have a flat surface, such as refuse bins.

Let's take a little look at this in more detail.

So first of all, the image that is required, in this case, our beautiful Oak symbol, is etched into the printing plate.

The ink then fills the etched design.

A soft silicone pad, that's the pinky red part, presses onto the plate to pick up that ink.

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

However, point to note, we need surface preparation at this point.

The surface of that polymer will need to be cleaned and degreased so that that ink sticks nicely.

And there we have it.

When the ink dries, the product is finished and the finishing is complete.

It can then be used.

Hydro-dipping is a process that can be automated.

A printed film floats on the water and transfers its aesthetic pattern onto a polymer surface when the object is dipped.

And you can see that in the picture of the polymer product there.

It's a little bit like how you can put marbling onto paper.

So you've got the printed film on top of the water, which is floating, and then you simply dip the product into that to pick up and transfer that pattern.

It's great, isn't it? Time for a matching check-in.

I would like you to match the image of the finishing process to its label.

So the labels we have are A, overmolding, B, laser engraving, C, pad printing, and D, hydro-dipping.

Have a go at matching.

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

Well done with all of your efforts with that, let's check your answers against mine.

So A, overmolding, matches with image three, the toothbrush.

B, laser engraving, matches with image four with the Oak symbol being laser engraved.

C, pad printing, matches with image one, the refuse bin.

And lastly, D, hydro-dipping, matches with image two, the polymer shoe.

Well done, folks.

Vacuum metallizing is a process used to give polymers a thin reflective metallic coating that is both lightweight and decorative.

So you can see it in this image of a blusher here.

And the next image too, you can see the metallic finish being pointed out.

It's often used to make a product look more expensive than it actually is.

It's used for toy parts, car interiors, cosmetic packaging, and other decorative polymer products.

Health and safety is an important consideration in industry so that workers are protected.

Measures include extractors, ventilation systems for VOC control, and PPE for human workers in manual finishing stations.

PPE may include respirators, gloves, and overalls to provide that protection for the workers.

Manufacturers need to consider the impact that producing products in volume has on the environment.

Considerations include VOCs, which stands for volatile organic compounds.

VOCs come from solvents and can cause air pollution.

Use of water-based or low-VOC alternatives is increasing.

Some finishes have chemicals that can pollute waterways, such as waste paints, dyes, inks, et cetera.

And wash-off water must be treated before being released into the water system.

Quick check-in.

What does VOC stand for and why is it a concern in polymer finishing? Is it A, very old coating, it reduces quality, B, volatile organic compound, can be harmful to health and the environment, C, vacuum over coating, used for sanding, or D, varnish oil composite, creating a strong seal? Have a think, come back to me when you've got the answer you think is correct.

Well done if you got B.

VOC stands for volatile organic compound.

And why is it a concern in polymer finishing? It is because it can be harmful to health and the environment.

Onto Task B.

Part one, a bottle lid has been injection molded.

Describe two finishing processes that the bottle lid may require.

Part two, compare two advantages of industrial finishing over small-scale finishing.

Part three, a company wants to finish 10,000 identical refuse bins quickly and with a professional logo.

What process should they use and why? And lastly, part four, explain one environmental consideration that manufacturers must take into account when finishing polymer products on an industrial scale.

Good luck with your answers, go for it, come back to me when you've got some great ideas.

Part one, a bottle lid has been injection molded.

Describe two finishing processes that the bottle lid may require.

You might have said a bottle lid will be removed from a two-part mold after injection molding.

It will require degating where the excess polymer from the point of injecting is removed.

It may also require deflashing from any polymer that has seeped out between the join of the two-part mold.

Part two, I asked you to compare two advantages of industrial finishing over small-scale finishing.

You might have said industrial finishing is much faster, allowing thousands of units to be processed per day.

It also offers more consistent results because machines apply the finish evenly every time.

In contrast, hand-finishing can vary depending on the person applying it and often takes more time.

Part three, a company wants to finish 10,000 identical refuse bins quickly and with a professional logo.

What process should they use and why? You might have said pad printing is an industrial finishing method used for transferring images to larger products that may not have a flat surface, such as refuse bins.

This ensures that the image is applied evenly and consistently.

Part four, explain one environmental consideration that manufacturers must take into account when finishing polymer products on an industrial scale.

You may have said waste materials like leftover finishes and cleaning solvents are disposed of responsibly.

These must be treated properly to avoid contaminating water supplies or harming ecosystems. Well done with your answers, folks.

This brings us to the end of our lesson today.

Let's summarize what we have found out.

Finishing improves polymer's aesthetics and function.

Small-scale methods of flexible for custom work such as polishing, vinyl cutters, and sublimation, industrial finishes uses machines for speed, consistency, and higher volume production, such as overmolding and pad printing.

Both must consider health and safety and environmental issues like VOCs.

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.