At London 3D Printing Services, we have a wide range of different 3D printing machines which we use for a number of different processes including our specialism which is SLS printing, or Selective Laser Sintering. This is a very high-end machine and requires specialist knowledge in order to use it properly.
A typical 3D printer is very similar to an inkjet printer, and it works by building up a 3D model one layer at a time, starting from the bottom up. It repeatedly prints over the same area in a process known as fused deposition modelling (FDM). However, it doesn’t use ink because that would never build up into anything very much, so instead uses some sort of thermoplastic which is molten and is extruded through a very tiny nozzle which moves around into the correct positions while being controlled by a computer.
The printer will print one layer and then wait for it to dry or set before printing the next layer. So it gradually builds up into a 3D model over a period which can take several hours, depending on what is being printed.
Of course, there are lots of different plastics around, and they can vary considerably in their chemical makeup and their physical properties such as the way they react to heat, light, and so on. One thermoplastic that is used widely in 3D printing is ABS – acrylonitrile butadiene styrene – which is composed of a very hard plastic (acrylonitrile) which is mixed with a synthetic rubber – the butadiene styrene.
This is ideal for 3D printing because at room temperature it is solid, and it melts at just over 100°C which is cool enough for it to melt in the machine and hot enough so that the finished product won’t melt in the sun! In its’ basic form it is a yellowish/white colour, but pigments can be added to it to produce any colour that you need. Depending on the printer being used, the plastic can be fed into it in the form of small pellets or filaments. ABS plastic is used widely in producing parts for computers such as the keyboard on your laptop and your mouse, and a lot of the interior parts of cars are made of it.
In practice, you don’t need to use plastic to print. It can be done using virtually any material which can be melted as long as it sets and hardens reasonably quickly. Researchers at Exeter University some years ago produced a prototype printer that could print using melted chocolate!
In Barcelona in Spain, researchers at the Institute for Advanced Architecture of Catalonia there have produced a 3D printed concrete bridge! This has been created out of segments that have been printed and then connected together. The bridge is 12 metres long and has been installed in a park in Alcobendas near Madrid. In Shanghai, engineers have created a similar bridge which is 26 metres long. These bridges use a lattice structure which has been designed with algorithms that have resulted in maximum strength, but while using less material.
Another company in Amsterdam has printed a bridge using stainless steel. It is presently being tested prior to being installed over a canal there. Over in Los Angeles, a start-up called Relativity Space is building a rocket which is mostly 3D printed. Their chief executive has said that printed metal doesn’t have the same qualities of heat dissipation as non-printed metal, but they have overcome that by adding cooling channels in geometries that can’t be manufactured in the usual way. Printers that have been designed over the last few years extrude molten metals through nozzles in the same way as ABS plastic.
At London 3D Printing Services, we have not yet got around to printing bridges and rockets, but the technology is fast-moving and being adapted all the time. We can produce your prototype very quickly using SLS nylon printing and we can also use batch production to craft single small items or larger objects that are a combination of many different pieces. Talk to us about your needs.