3D printing is the process of creating a physical object from the successive layering of material. This process is predominantly controlled via a computer, with the original object either being scanned in or created from scratch via a computer 3D modelling tool like Autodesk 360, Solidworks or OnShape (there are loads of these!).

Once a computer model is created, it is then ‘sliced’ into hundreds or even thousands of layers, essentially turning a 3D shape into lots of 2D sheets. These 2D layers are then turned into‘G-code’, this is a set of coordinates that the computer uses to direct the 3D printer. The layers can then be printed on top of each other, until you have your desired shape.

3D printing is also known as ‘additive manufacturing’, this is because, unlike a wood carving for instance where you are taking bits away to create an object (reductive manufacturing), 3D printing doesn’t have any waste (technically!) as you are creating an object with exactly the amount of material you need.

There are multiple different kinds of 3D printing, such as;

Stereolithography (SLA)

: This uses a process called Photopolymerization. A liquid that has the property of hardening when exposed to certain kinds of light, called a photopolymer, is used as the basic source material.  A laser or UV projector is then used to harden the polymer, layer by layer, eventually creating a 3D object. SLA prints can be highly detailed with layers as thin as 25 microns, although the liquid is quite expensive and the prints can be brittle.

Fused Deposition Modeling (FDM)/Fused Filament Fabrication (FFF)

: FDM is the the type of 3D printing that you will find in most makerspaces and people’s homes. It heats up a material, usually a form of plastic (most commonly ABS or PLA) then extrudes it from a nozzle, which moves back and forth according to the specified G-code, creating layer after layer of plastic and building up to create a 3D model. The material used in this process is generically called ‘filament’.

FDM/FFF material is quite cheap and the mechanics used are relatively easy to understand. This has led to an explosion of open source printers that have played a large role in making 3D printing something that consumers can now use in their homes. This prints might not have the detail of SLA, but they are often stronger and come in thousands of different colours and textures, like wood or ceramic.

Selective Laser Sintering (SLS):

There are a number of granular binding methods, but this is the most common.  SLS uses fine powdered material, usually a metal but also ceramic and glass, and fuses it all together using a high powered laser that scans over it one layer at a time.

This method is probably the most accurate and creates really strong prints, making it possible to actually develop end products with this rather than just prototypes. SLS has the ability to create intricate, almost impossible geometry, making it possible to create aerospace parts or surprisingly, a lot of art. SLS is the process favoured by the 3D printing house, Shapeways.

Laminate:

This isn’t used as often as other printing processes but is an interesting becuase it uses normal paper as the source material. The process cuts out this paper and then bonds it together using specialist adhesives and pressure. The main printer that uses this is the MCOR range. One of the main benefits of this type of printing is that it can create full colour prints.

There are other forms of 3D printing, but these are the main areas you’ll find in commercial and consumer printing. The time is takes to print a 3D object varies greatly between process and relies on size and type of object. The speed is getting faster all the time, but on an average FDM machine, you’ll be looking to print a 2 inch cube in about 30 minutes.