3D printing was invented back in the 1980’s by Charles “Chuck” Hull, and in 1986 he founded 3D Systems in order to commercialise his technology. 3D printing has come on in leaps and bounds since those days, and you can now get everything from a small home 3D printer for less than £150 up to the top-end SLS nylon printing machines that we use at London 3D Printing, and which can cost upwards of £50,000. SLS stands for Selective Laser Sintering.
Sintering is the process of compressing and forming a solid mass of material either by heat or pressure, without melting it to the point where it becomes liquid. An example of sintering is when ice cubes in a glass of water stick to each other because of the difference in the temperature of the water and the ice. Pressure-driven sintering is similar to compacting snow hard into a snowball.
A 3D printer builds up a 3D model layer by layer, starting at the bottom and repeating the process in a method known as fused deposition modelling. It works somewhat like an inkjet printer operated by a computer and creates a 2D print layer that sits on top of the previous one, time after time, the computer controlling it into any shape desired.
Of course, an inkjet printer uses coloured ink to print but you cannot build a 3D object using coloured water, so a 3D printer will often use plastic, or more accurately, thermoplastics, which melt when you heat them and return to solid when they cool down. Typically, this would be ABS – acrylonitrile butadiene styrene – which is the plastic that Lego bricks are made from. The printer extrudes a tiny jet of molten ABS through a nozzle, printing one layer, waiting for it to dry, and then printing the next layer.
However, our SLS professional 3D printing services use nylon powder instead of ABS and use a laser to set each layer before printing the next one. Compared with other types of 3D printers, the nylon used is extremely strong and can produce very fine details. It also results in a very fine finish which means that less work is needed in the later stage of manufacture. The SLS printer can produce extremely complex shapes and designs, and we can produce products up to a maximum 300mm x 350mm x 450mm.
There are six processes needed to craft your prototype, the first of which is a file in 3D format which can be created by 3D scanning of an existing object or by using Computer Aided Design. It then needs to be converted to STL format, STL meaning stereolithography, which is also known as Standard Triangle Language.
Next, the STL file needs to be checked for errors and there can be an awful lot of them! There are certain procedures that need to be followed, because it is not just a case of sending lots of layers to the SLS printer. The printer needs to understand how the layers connect with each other so that it knows what the next step should be.
Now that the STL file is ready, we have to cut it up into layers, and we need to determine the size of the layers, which will not only affect how coarse or fine the finished print is, but also the amount of time taken to produce it.
Finally, it is time to set the printer going, and we have to keep a beady eye on it to make certain it doesn’t run out of the nylon powder and that it is running correctly, as it needs to for our professional 3D printing services.
Following this is a process called architecture, which may be removal of a base in many 3D printers, or taking a very heavy box of nylon powder out of the printer and finding the pieces in the powder. When we have the pieces, they then need to be checked over and we may need to finish the surfaces in order to ensure they are perfect.
Then they can be finally finished by painting, polishing, chroming, or whatever, so that your prototype is there – at last – for all to see.