Lesson video

Hi there everyone, my name is Mr. Booth and welcome to your Design and Technology lesson for today.

It's fantastic you could join me.

Today, we're going to be looking at computer-aided manufacturing and how you can use 3D printing to manufacture your prototypes.

This lesson is part of the iterative design student living under the context, communal areas.

Today's outcome, I want you to be able to prepare and manufacture a 3D model using computer-aided manufacturing.

We have three key words for today, the first being filament, the thermopolymer used by 3D printers to create those objects.

And one of the types of 3D printers we're going to be looking at is fused filament fabrication, FFF.

And if we're going to use 3D printing, we have to think about design for manufacture, DFM.

So there our keywords for today.

We have two learning cycles.

The first is all about 3D printing, so let's take a look.

3D printing is known as an additive manufacturing process.

If we remove material, it's described as a wasting process.

We're wasting that material.

We're taking it off whatever we started with to make our product.

3D printing is the opposite of that.

Material is added in layers, which actually means there's almost no waste at all.

And here we have three of the most popular 3D printing technologies that you will find.

The first is the one we are looking at closely today, fused filament fabrication, and it uses a polymer filament as its material.

And the way we solidify that polymer, because we have to heat it up to create a shape, is just using temperature.

Once it returns to room temperature, once you've heated it up, you then have your product.

But we also have stereolithography, SLA.

Now this uses a resin, a photopolymer resin that can be hardened with light.

So a light source is used to create your products, your models.

And then finally, we have selective laser sintering.

Now this uses a powdered polymer, or sometimes a metal, and it uses a laser beam to fuse together that powder to create your model.

So three examples there, all of them additive manufacturing processes, all of them with very little waste.

But we're going to focus on FFF today.

Now with 3D printers, material is deposited in layers.

3D printers deposit different materials, including solid, powdered polymers, resins, and you can even get some 3D printers that will deposit in concrete to make homes.

Fused filament fabrication 3D printers heat the filament before depositing.

There are two points where the temperature can be controlled in the print head using print elements and also the nozzle gets quite hot as well.

And of course, the print bed, the surface you are printing your model onto.

And these can be adjusted for different materials.

And here's some examples.

So a very popular material is PLA.

We'll have a look at what that means in a moment.

And your printing temperatures for this range between 190 to 210 degrees.

And then also you can heat your print bed as well, generally between 60 and 70 degrees.

But we also have ABS as well.

Now ABS needs slightly higher printing temperatures and for that reason you also increase the bed temperature as well because your material is coming out a lot hotter.

Now most 3D printers in school use the process called fused filament fabrication.

Now this is when material is heated, it's passed through a nozzle and then the building it parts layer on layer on a print bed.

Now let's just have a look at what fused filament fabrication actually means.

Now you might have also heard this as fused deposition modeling, but I actually prefer fused filament fabrication because I think it fully explains what is happening inside that process.

So first of all, fused.

Well, each layer of the print is fused by heat, one on top of the other.

Filament, well, that's the material we are using, the thermopolymer that we are using, and it's provided usually in big spools.

And then we have fabrication.

Well this comes from the word "fabricationem" which is quite difficult to say, which obviously, I struggled with it a little bit there, meaning structure, construction or making.

So when you break down each of those you can see what it actually means, fused filament fabrication.

Quick check for understanding, what type of manufacturing process is 3D printing? Is it A, addition.

B, subtraction.

C, wasting.

Or D, additive.

Pause the video now, have a go at this and come back to me when you've got your answer.

It is of course, additive.

Well done.

Now we're going to look at a very simplified diagram of a fused filament fabrication 3D printer.

So here we have our printer.

You can see we've got our filament.

We have our print head.

That's where the filament is heated up by printing elements.

We have the nozzle, which is the very precise end, usually a 0.

4 millimeter hole in it to pass through that heated filament.

You have the model that you're building layer upon layer, the heated print bed, you have the z-axis down at the bottom there, and then of course the filament on the spool, usually stored somewhere next to the printer.

So let's have a quick check for understanding.

There are some missing labels from this FFF 3D printer.

Can you fill them in? Pause the video now, have a go at this, and come back to me when you've filled them in.

So the missing labels are of course filament, nozzle and print bed.

Well done.

Now 3D printing is called 3D printing because, of course, the printer moves in three directions along three different axes.

It has to because you're making a 3D object.

Just is exactly the same in your CAD program or CAD application that you've been using, you're working in 3D and it's the same with the 3D printer.

So we have the x-axis which is across the front of the 3D printer going left to right, the y-axis going front to back and of course, the z-axis going up and down.

Now if you observe a 3D printer working, you will see it working mostly in the x and the y-axis as it builds the layer of your model.

The z-axis happens every time it needs to do a new layer.

Now when using a CAD application, your 3D model will be created and you can see we've got Alex's model here.

The model is then exported as a.

stl file, that's the file type that we use for 3D printing in an application such as Fusion 360, this is done by saving the part as a 3D mesh.

And what that does is it converts your model into triangles as a mesh which can be then used with a post-processing application such as a slicer ready for 3D printing.

Check for understanding.

What file type is used to export models ready for slicing? Is it A,.

stl.

B,.

prt.

Or C,.

jpeg.

Pause the video now, come back to me when you've answered.

It is of course,.

stl.

Well done.

So now we have exported our model as the stl file, the.

stl file, the models need to be prepared for printing using a slicing application.

We call this post-processing.

Now there are a number of different variables that can be set within whatever slicing application you are going to use, but those basic settings might include the layer height.

Now on my 3D printer, this generally ranges from 1.

0.

16 millimeters for a fine quality print all the way up to 0.

28 millimeters for a draft quality.

You can even go below that if you want an ultra-fine quality as well.

You can also look at things like the infill density.

Now we don't print solid objects.

That would be extremely expensive, it would take a lot of time and you generally don't need to because you're 3D printing, you're making a prototype.

So to save on material, what we tend to do is only have around a 15% infill as standard.

It creates like a honeycomb structure inside.

Support structures, if they are needed, if you have overhangs or bridges that span quite a long distance, you're probably going to need support structure.

So you need to decide where they are and how much of those you use.

And then finally, bed adhesion.

That first layer of 3D printing is the most important.

If you get that right it tends to mean that the rest of your print will carry on as normal and it won't fail.

So that's really important and you can use things like what we call skirts and brims to help you with that.

So let's have a look at some example prints when we're talking about the different settings that you can have.

So here we have a calibration cube, an XYZ cube that you often print when you want to make sure your printer is working correctly.

So the first one is an ultra fine print.

We're using a standard nozzle 0.

4 millimeters.

We've got a layer height of 0.

08 millimeters.

That's very fine, a very small layer height.

The print time is 39 minutes.

It's quite a small cube this.

39 minutes is quite a long time and we've used about 1.

4 meters of material.

If we have more of a standard layer height, so we've got 0.

16 millimeter layer height, you can see we've actually reduced the print time by 11 minutes and used the same amount of material.

And I'm sure you see from the images, you can barely see the difference between them.

And then finally the draft print.

You can probably see the difference between them here, the quality is reduced, but we've increased the layer height, you can see 0.

25 millimeters, but once again, we've knocked another 10 minutes off the print time.

So you can see by amending these different settings, you can drastically reduce the print time, but also change the quality of your final prints.

Now this diagram shows a cross-section of how the filament actually moves through the printhead.

So you can see we have a coil or spool of filament that's usually stored next to the machine.

We then have how the filament is moved through the machine by rollers connected to stepper motors so it's very accurate.

We have the heating elements and then the nozzle, the standard is 0.

4 millimeters in diameter as we know and then obviously, the print bed where the filament is deposited in layers, it cools and solidifies and then you get your model.

So we know that the material is deposited and then it goes through a process which we call solidification.

The layers are fused together.

We know that from the name of the process, fused filament fabrication.

And this method of fusing varies depending on the type of 3D printer.

Some use heat like fused filament fabrication, but some use light or even ultraviolet light, UV light.

Now, most fused filament fabrications solidify by cooling to room temperatures.

So once it's cool, you can take a model off the print bed and there you go, you've got your prototype.

So let's have a look at some products and some advantages of 3D printing.

So these are Kibu headphones and they're designed for children.

The brilliant thing about Kibu headphones is they're modular, they can be 3D printed and then assembled by children.

Recycled filament is used, parts can be easily replaced, while the used parts can be recycled and even turned back into new filament.

Isn't that fantastic? So let's have a look at some other benefits of using 3D printers.

Well, Lucas says, "3D printing allows manufacturers to change the design quickly and easily.

This means they can customize a product to meet individual needs." It's easy to create complex shapes which would be difficult or impossible to produce with traditional manufacturing methods.

Thank you, Alex.

Sam says, "Very little waste is produced which is important for sustainability." Remember it's an additive process so we're adding material there's almost no waste at all as long as you're not using things like support structures.

And then finally Laura says, "3D printing is often used in schools, factories and design studios because it saves time, it doesn't waste materials and produces consistent outcomes." So we're now on to your first task.

I would like you to use notes and diagrams and describe how a fused filament fabrication 3D printer works.

Next I want you to describe the benefits of using 3D printing technologies.

Pause the video now, have a go at this task and come back to me when you've completed it.

So how did you get on? Well, using notes and diagrams, describe how a fused filament fabrication 3D printer works.

So your answer obviously can include your diagram which hopefully you've labeled.

A polymer filament is passed through heating elements which heat and liquefy the material.

The material is then passed through a precise nozzle and deposited onto a heated print bed one layer at a time.

Following a code produced by slicing software, the printer will move on the x and y-axes, building each layer.

The print bed or the print head assembly will then move in the z-axis beginning the next layer.

As the material is deposited, it cools and solidifies, creating the model.

Describe the benefits of using 3D printing technologies.

Well, 3D printing enables manufacturers to modify designs quickly and easily.

Parts can be customized to meet individual needs.

Complex shapes, which would be very difficult to make using traditional manufacturing methods, can be printed easily.

Very little waste is created during the 3D printing process.

And finally, recycled filament can further reduce environmental impact.

Well done.

So we're now on to the second learning cycle, design for manufacture.

When designing, it's important to take into account how the product will be manufactured.

This is the same for creating prototypes using 3D printing, considering manufacture when designing can reduce the manufacturing cost, minimize complexity and avoid unnecessary parts, use materials and processes that are practical and improve the quality and consistency.

It can also speed up production, which again, is something very beneficial.

This all is called Design for Manufacture or DFM.

There are basic DFM rules to follow when producing models for 3D printing.

This is a 3D printing reference model.

It can be used to check the capabilities and limitations of FFF 3D printers.

It can be used to inform designs to help improve the quality of 3D printed models.

So let's have a look at some of those basic 3D printing rules.

First of all, overhang shouldn't be more than 45 degrees without support.

Wall thicknesses should be at least double the nozzle diameter.

If you've got any rods that need to go into holes, you need to have a clearance, and 0.

2 millimeters is about the minimum of that.

Bridges should not be over 10 millimeters without support, 20 millimeters at a push.

And of course, embossing and debossing thicknesses should be at least double the nozzle diameter.

Let's have a closer look at those and see if I can give you some tips when you are designing your models.

So overhangs.

So we know that any overhang greater than 45 degrees will have reduced quality.

Models with large overhangs will require support and increase complexity and waste material.

So you can see, we've got an overhang of 67.

5 degrees there.

The quality of that overhang on the underneath will be reduced because you're printing in midair.

Top tip, redesign models to reduce overhangs.

What degrees should overhangs not exceed? We have A, 35 degrees.

B, 45 degrees.

C, 90 degrees.

Or D, 135 degrees.

Pause the video now, have a go at this and come back to me when you've got your answer.

It is of course, B, 45 degrees.

Wall thicknesses.

Very thin walls less than one millimeter will be weak and might not print properly.

Unnecessary thick walls will increase print time and waste lots of material.

So you can see here we've got some wall thicknesses the 0.

8 millimeter wall will probably just break, whereas the other ones will be a little bit stronger and are much better for material use.

So the top tip, wall thicknesses should be between one millimeter and two millimeters where possible.

Quick check for understanding, what should wall thicknesses be less than? A, 0.

5 millimeters.

B, one millimeter.

C, 1.

5 millimeters.

D, two millimeters.

Pause the video now, have a go at this and come back to me when you've got your answer.

It is of course, D, two millimeters, well done.

Part orientations.

Now this is really important.

Printing tall takes much longer than printing wide.

Part orientation will impact the number of layers and the final finish.

So you can see here, this is how I orientated this reference model if I was going to 3D print it with these axes.

So a top tip, design and orient models to minimize height.

Bridging.

We've already talked about this, but horizontal spans without support should be a maximum of 20 millimeters.

Models with large bridges will require support and that increases complexity and wastes material.

You can see we've got our bridges there and you'll see the quality reduced of the one that's 20 millimeters.

So a top tip, keep bridges between 10 millimeters and 20 millimeters.

Check for understanding, what is the maximum distance an unsupported bridge should be? Is it A, five millimeters.

B, 10 millimeters.

C, 20 millimeters.

Or D, 40 millimeters.

Pause the video now, have a go at this and come back to me when you've got your answer.

It is of course, 20 millimeters, well done.

Tolerances, fits and holes.

Part tolerance will vary depending on the machine you are using and the only way to really find this out is just to experiment by printing those parts and seeing if they fit together.

Holes, joints and sliding parts will need to have clearance to work and you can see here, I've got a rod and I've got a hole that I want that to go in.

So a top tip for this is that allow a minimum clearance of 0.

2 millimeters on assemblies and also orient holes vertically.

It's much better if it's printing with the hole facing upwards than it is if it's facing to the side or to the front.

Cooling and warping.

Large flat parts might warp when cooling.

There's not much you can do about that.

What that means is as a part of the made of the polymer starts to cool, what will happen is the edges will start to curl up.

Now filament choice and heating is a really important factor in this and the actual base of this part here might warp in the corners if we're not careful.

So a top tip for this is round the edges, use brims and rafts and also make sure you are utilizing the heated print bed if you have one.

We then have lots of different filaments, filament choice that you can choose from.

PLA is versatile, it's a bioplastic, biodegradable in certain conditions and it has a very low odor, but it's also brittle and sometimes prints will sag or warp in certain environments.

We then have TPU, excellent layer adhesion and it gives you a real surface finish, but it is flexible, you've got to consider that and it's not suitable for all FFF printers.

We then have ABS, now obviously, this can resist higher temperatures and it's a lot tougher.

But prints can warp and it also shrinks when cooled so you have to really think about temperature control with ABS.

Quick check for understanding, which is the most suitable filament to choose for a prototype which will only be used to test a design? Is it A, TPU.

B, ABS.

C, PLA.

Or D, PET.

Pause the video now, have a go at this and come back to me when you've got your answer.

It is, of course, PLA.

The final thing I'm gonna say on this is filament.

You've got to store your filament correctly.

It can absorb moisture from the air it sits in, and that will not help with your 3D prints or your 3D printer.

So make sure it's stored in a suitable vacuumed environment.

Right, we're on to your final task, task B.

What you need to do is prepare your prototype for manufacture by modeling your 3D design using the CAD application of your choice.

Use DFM 3D printing rules to refine your model and describe how you will ensure a successful print.

Export and slice your model, 3D print your model and evaluate your prototype.

Pause the video now, have a go at this and come back to me when you have done it.

So how did you get on? Well, hopefully you designed your model and it might look something a little bit like this using the CAD application of your choice.

I then asked you to use DFM3D printing rules to refine your model and describe how you will ensure a successful print.

Let's look what Alex did.

I'm using PLA filament as it is a versatile material.

I ensured that there were no overhangs and all walls were between one millimeter and two millimeter thick, and I also shelled the model to reduce material.

The print was oriented so that it was wider than it was tall and I added rounds or fillets to all the edges to reduce warping and help with part cooling.

Finally, I wanted you to export and slice your model and then 3D print and then evaluate it.

Here we can see Alex's model and the successful print that he has produced.

The model printed well with no issues.

The print time was significant.

For future iterations, I'll reduce the wall thickness to the minimum.

I will also add larger internal rounds to improve quality.

Printing the parts separately worked well and reduced print time.

Well done, Alex.

So that brings us to the end of today's lesson.

Let's have a quick summary.

3D printing is known as an additive manufacturing process.

Most 3D printers in schools use a process called fused filament fabrication in which heated material is passed through a nozzle building parts layer by layer on a print bed.

3D models need to be prepared for printing using a slicing application.

3D printing allows manufacturers to change the design quickly and easily.

And finally, there are basic design for manufacture rules to follow when producing models for 3D printing.

You've all been absolutely fantastic today.

I look forward to seeing you all next time.

Goodbye.