What do we mean when we talk about 3D printers? For most of us, we mean the kind of 3D printers we have at 3D Print Works – a MakerBot Replicator or a Reprap. This uses one type of technology (FDM) but there are other types of 3D printers available which this article will explain.

Fused Deposition Modeling (FDM)

It sounds complicated but this is the technology used by the printers we have at 3D Print Works. Popular brands are the Reprap, MakerBot, Cube, Cubify, Ultimaker and UP! to name only a few.

Material, usually in the form of coiled filament, is fed through the print-head and heated. The material melts and is then extruded through a nozzle. The printer lays down a layer of material on to a platform. This platform moves down a little and the next layer is printed. The object is slowly built up one layer at a time. Some printers work a little differently in that the print-head moves up while the platform remains at the same level (such as the Delta Rostock).

The most popular materials used are PLA and ABS, which you can buy here, but a range of plastics can be used.

Let’s see a printer at work! Here is our Makerbot in action. How quickly can you work out what is being printed?

Stereolithography (SLA)

This technology was developed in the 1980’s by Chuck Hull and initially used liquid photopolymer materials which harden under Ultra Violet light. A special liquid is placed in a vat. Light is exposed to parts of the liquid, layer by layer, controlled by a computer. Gradually solid object forms from the vat. Excess liquid is drained away.

The technology has been developed to be more similar to a normal 2D inkjet printer. The liquid is sprayed on to a platform only where it is required. The light is passed through the liquid to solidify it. The print-head moves to the next layer and so on to build up an object. The Stratasys Objet is an example of this technology at work.

Both of these  methods produce a high-quality product but the machines are expensive and therefore more suitable for commercial use rather than home or office use.

Granular Binding

There are a number of techniques in this category. They all use powders which are bound together in some way to form a solid object.  The results can be of a high quality, can even be in full colour and use a large range of materials, including metals.

Selective Laser Sintering (SLS) – This is simular to SLA but uses a vat of powder. The powder hardens not by UV light but by laser light.

Inkjet – Again, the inkjet model can be used, where the powder is sprayed on, a layer at a time.  A liquid binding material is sprayed between each layer of powder. The advantage of this method is it allows for full-colour objects to be printed.

Electron Beam Melting (EBM) is used for metals, where the metal powder is melted by an electron beam.

Selective laser melting (SLM) is where the powder is melted using a high energy laser beam.

Like SLA, all of these methods use expensive equipment and are therefore used mainly in commercial environments. Let’s see SLS at work in this video.

Other Methods

A number of other technologies are employed. Lamination uses layers of paper bonded together with an adhesive.  There is also the syringe method in which soft materials can be extruded through syringes.  This is used for cake icing or chocolate. The material is used raw or it can be heated slightly.

In the bio-technology world, there are also exciting things in progress. Scientists are working on ways of 3D printing human tissue, so going to the doctor in the future could well be a very different experience.