The Basics of 3D Printing

Michealangelo once said “In every block of marble, I see a statue… I only have to hew away the rough walls that imprison the lovely apparition to reveal it.”

Well, that’s just beautiful.

But imagine how much material was wasted in the process of Michelangelo turning an unassuming hunk of marble into a sculpture as intricate as the David.

Chunks and slivers of countless irregular shapes were probably just thrown away because well, what else would you do with them?

In the 400 plus years that have passed since Michealangelo and his renaissance compatriots were chipping away at blocks of stone, things have barely changed.

Sure, instead of manually producing things, we’ve figured out how to squish them really close together and get a machine to do the rest. But, there’s still waste.

Copious, horrible amounts of material waste.

The United States alone produces 7.6 billion tonnes of industrial waste per year (3.04 billion elephants).

This is essentially just little almost imperceptible scraps that come from factories which add up because no one wants to figure out a better way to use them.

What if we could figure out a way to use these 7.6 billion tonnes of waste? Or better yet, not even have to produce them?

Not only would this spare our already compromised environment a lot of unneeded material pollution, but companies, manufacturers and producers of all kinds could save money because they wouldn’t need to use so much material for one product.

Enter 3D printing, a technology which has the potential to do just this.

What is 3D printing?

Today, if you were to produce something like, say, a miniature robot statue, you would use something called subtractive manufacturing. This is what we all envision manufacturing to be: you take a block of something and cut away the excess until you are left what you need.

3D printing, on the other hand, is known as additive manufacturing — instead of getting rid of everything that isn’t the robot, you only add what is.

Specifically, adding to the robot layer by layer until you get the entire thing.

How does it work?

3D printing works in three main steps: design, printing and post processing.

Design

In order to design your robot, you use something called Computer Assisted Design (CAD) software. There are many different available CAD platforms out there, some of the most popular ones include TinkerCAD, Fusion 360, Solidworks and AutoCAD.

Then the design is converted to an .STL file which slices it up horizontally into a bunch of tiny cross sections. The file is then uploaded to the printer, and you’re good to go.

Printing

There are seven main kinds of 3D printing.

Material Extrusion

Material Extrusion is the most common type of 3D printing. If you’ve ever seen 3D printing before — it’s probably material extrusion.

1. A filament (like plastic) is heated to a liquid in a cartridge.
2. It is pumped out the extruder. The extruder is kind of like a pen which draws out the shape of a layer on the platform.
3. The plastic cools and the platform moves down.
4. Repeat with each layer being printed on top of the one before it.

Directed Energy Deposition (DED)

Directed Energy Deposition is like material extrusion, but it extrudes powder instead of heated filament. As the powder comes out of the extruder, a laser is aimed at it and hardens it into a more compact form.

Vat Photopolymerisation (VPP)

A photopolymer is a polymer (a chain of one kind of molecule that repeats over and over) that changes properties when exposed to light.

1. Fill a vat with a liquid photopolymer resin.
2. A platform is suspended in the vat a few micrometres under the surface of the resin.
3. A laser is shone at the resin and marks out the image of one of the object’s layers.
4. In the places where the light contacts the resin, a photo initiating material reacts with the polymer to form unbreakable bonds, and so it hardens or cures to the platform. The resin will typically be a mix of acrylate to speed up curing time and epoxy to prevent shrinkage.
5. The platform moves down until the hardened shape is just submerged under more liquid resin.
6. Blades will move across the surface of the resin to smooth it.
7. Repeat over and over again until you have the whole shape.

This process is known as the bottom-up approach: the platform gradually moves down, and the laser shines from above.

There is also the top-down approach where the platform gradually moves up and the laser shines from below. In this case, each new layer of the object is cured to the bottom of the vat. So each time we go to print a new layer, we have to peel. In order to prevent the cured resin from sticking, the bottom of the vat is made out of silicon.

Stereolithography (SLA) is a kind of VPP which uses a UV laser to “draw” a layer onto the resin. This laser is directed using galvanometers — effectively mirrors which point the laser in the right direction.

Digital Light Processing (DLP) is a “sister technology” to SLA which projects a whole image of a layer onto the resin. So, instead of needing to mark out each individual pixel, the entire image is marked out on the resin at once, making it much faster.

Continuous Liquid Interface Printing (CLIP) is similar to DLP in that it uses a projector. It is commonly done using a top-down approach, but in order to get around the peeling stage, they’ve made the bottom of their vat oxygen permeable (oxygen can get through). This oxygen creates a dead zone in the bottom most micrometers of resin so it is not cured and instead the resin a couple micrometers above it is cured. Nothing sticks!

Material Jetting

Material Jetting is very similar to VPP but instead of using a vat full of resin, we simply spray the thin layer of resin directly onto the platform, the light cures it and a new layer is sprayed on top.

Power Bed Fusion

Power Bed Fusion is also quite similar to VPP, but instead of using resin, we use a powder which is hardened using a laser.

Selective Layer Sintering (SLS) is the most common type of Power Bed Fusion in which the laser “selectively sinters” — or hardens the powder much like it does to the resin in SLA.

Binder Jetting

In Binder Jetting

1. A layer of powder is deposited onto the platform
2. A binder (kind of like glue) which holds the powder together is dropped on top in the shape of a layer.

Sheet Lamination

This is probably the most uncommon type of 3D printing in which a sheet is pasted on the platform, a laser selectively hardens it and another sheet is placed on top.

Post Processing

So, now that you have your robot (in whatever way you prefer), we need to post process it — more or less adding the finishing touches so that it can sit happily on your desk.

There are many different ways post processing is done, and they largely depend on the kind of 3D printing that was used.

1. Supports are cut off. When printing shapes that have an overhang, thin supports are often printed to give the object more stability (particularly for things like material extrusion, this can be almost necessary when you would otherwise be printing in air). These supports can be snapped or cut off easily afterwards.
2. The supports will leave bumps which can be sanded away using sandpaper alone or sandpaper and mineral water to give it a smoother finish.
3. Techniques that involve lasers usually call for the objects to be put in a post curing chamber where they are exposed to more light and harden even more.
4. Techniques involving powder are sometimes put in a heat chamber where moisture can evaporate, and through infiltration, a liquid metal is pumped into it. The metal then hardens and gives the structure more integrity.
5. Rinsed in alcohol and water to get any residue off.
6. Objects are spray painted to prevent yellowing from UV exposure and hide the build lines.
7. Polish to give it a glossy or matte finish.

So, why do we care about 3D printing?

Well, besides the obvious fact that 3D printing allows us to save more material, it also allows us to have on demand consumption.

Let’s say you started a company that produced plastic robot figurines. You are in your first year, and you’re not sure whether or not people will actually want to buy your plastic robots. But in case a whole bunch of people do want them, you want to be able to have them ready to go.

If you were to conventionally produce your robots, you would print a whole bunch of them, stick them in a warehouse and wait for people to start ordering them. Problem solved.

BUT. What if no one orders them (or at least, not as many people as anticipated)? Then, you’re left with a whole bunch of plastic figurines and nothing to do with them but let them collect dust.

Presumably, these robots would just sit in your warehouse where they are taking up valuable land (not good for the environment) that needs to be paid for (not economically efficient).

However, if you used 3D printing, whenever you got an order you could load up your design, print it and send it off. That way, you won’t have an incredible surplus of robots wasting away in a room somewhere.

3D printing also allows things to be done locally. So, instead of you having to harvest the materials for your robots from Location A, fly it across the world to make it at Location B, combine it with packaging from Location C, fly it across the world again to a distributor at Location D and finally delivered to a robot enthusiast at Location E, you can just get all the raw materials from Location A and make it at Location E.

That takes a lot less time, money and also reduces the amount of distribution emissions produced in the entire process.

So then, you might say, what about the jobs?

Yes, presumably if everyone was to make everything they could ever want using their own personal 3D printers, many of the factory jobs that exist today would be lost. But, we are not yet close to the point in which this could be the case.

For starters, 3D printing is only really capable of making things out of metal and ceramic — and this usually requires industrial level 3D printers that can’t just perch happily on your counter at home.

The most common filament is plastic or plastic resin, and well, society in general is trying to move away from that whole genre of materials. And understandably so, for reasons we’re probably all familiar with. Plastic filament in particular wears down quickly which means that functional parts will often need replacement. There is the possibility of using recycled plastic filament — using waste plastic instead of just letting it decompose in a landfill. But, in the long term, no plastic would be the best bet.

And well, who really wants to wear a shirt made of ceramic? Many of the products that we do consume involve more malleable materials than plastic, metal and stone.

Additionally, 3D printing is energy intensive. Ideally, 3D printing might one day be this technology that could produce anything we would want to own, just using less resources. But we have yet to satisfy this ideal. It currently takes 50–100 times the energy to 3D print an object than it would to produce an object of the same weight using conventional practises.

Why? Well, because factories have become SO efficient at pumping out stuff (and to be fair, they have had a 200 year head start).

What can 3D printing be used for?

ICON Build: 3D printing houses

ICON Build developed the Vulcan 2 printer — a massive 3D printer which can print a 400 square foot home in 24 hours. Even better, their homes cost $4,000 and have the same thermal envelope, moisture barrier, heating, plumbing and electricity as a conventional house.

The homes are made by extruding a specific concrete mix in layers as the wall and adding windows, doors and a roof manually.

Their first prototype was done in Austin, Texas and their second trial pair was in Tobasco, Mexico. They are planning on doing a trial community in a low income part of El Salvador where many people are homeless or an without adequate housing.

Aleph Farms + 3D Bioprinting Solutions: 3D printing meat

Aleph Farms is a cellular agriculture company which managed to 3D print a steak in space! In a partnership with 3D Biprinting Solutions, they sent up a whole bunch of beef cells to the International Space Station where they were loaded into 3D printer and extruded.

The success of this technology is going to help scale food options available to astronauts (and probably change the way we produce our meat).

Adidas + Carbon 3D: 3D printing shoes

Adidas partnered with Carbon 3D (responsible for the CLIP VPP printer) to print their FutureCraft 4D sneaker. The shoe’s sole is entirely printed out of a white plastic and is available in carbon black and carbon white.

In the future, Adidas is thinking about 3D printing customizable soles specific to each client.

Limbitless Solutions: 3D printing prosthetics

Limbitless Solutions are most famous for the Iron Man prosthetic hand that they gifted to 7 year old Alex Pring in a video that went viral in 2015. This company produces 3D prints prosthetic hands that would cost $10,000 for a tenth of the cost and gifts them free to kids in need.

Most prosthetics that have been 3D printed are wrists and arms — the plastic we typically use is not capable of bearing full body weight like a leg would.

University of Washington: 3D printing solar panels

In 2009, scientists discovered that perovskites (a calcium titanium oxide crystal with superconducting abilities) have photovoltaic properties and could be used in solar cells. However, they were very delicate and could only be applied to glass which result in very bulky, heavy solar panels.

Recently, scientists found a way to turn them into ink and coat flexible foils with them. The University of Washington is working on creating Roll to Roll Solar Panels which essentially take this ink and print it onto sheets of plastic to make strip like solar panels.

These strips could then be used on windows, doors, roofs, or really whereever as a more subtle alternative to the current solar panel.

Key Takeaways

1. 3D printing is a kind of additive manufacturing that works by assembling an object layer by layer.
2. There are seven kinds of 3D printing: Material Extrusion, Directed Energy Deposition, Vat Photopolymerisation, Material Jetting, Binder Jetting, Powder Bed Fusion and Sheet Lamination. Most of these work by dropping a powder or resin and hardening it with a binder or laser.
3. There are many different kinds of post processing techniques which largely depend on the kind of 3D printing you use.
4. 3D printing has the potential to make production more cost effective and environmentally sustainable, however it needs to overcome the challenges of more versatile printing materials and energy use.
5. Some 3D printing innovations include ICON Build’s house, a steak on the ISS, Adidas shoes, prosthetic limbs and roll to roll solar panels.

So, to all the future Michelangelo’s entertaining romantic notions of scraping at blocks of stone until you find the world’s next masterpiece and billionaires developing armies of plastic robot figurines:

THERE’S A BETTER WAY — namely, 3D printing.