For a long time, having a device that allows us to make an object to our liking at the touch of a button was the stuff of science fiction. Well, as we are used to, technology is catching up with us, and some time ago technology came to light that allows us mere mortals to really conjure up a real product in physical form from a digital record. With some limitations, of course, but still relatively simple. But why would you really need it? So we don’t have to go to the shops and print the products ourselves? Well, it hasn’t happened in that form yet, but things have progressed a lot and let’s see what we can really do. It is all described below in layman’s terms, so that hopefully it will be understandable to all.
Why?
First, let’s ask ourselves – why do we need this? The technology itself is quite fascinating, but its practical value is in applications where we need a unique product that cannot be bought or obtained and that we have created ourselves in a digital environment. So what can we create? It is probably not the first purpose to print toys for your children, although people do that too. In the first phase, when the technology advanced to a usable level, it was mainly engineers, designers and planners who grabbed the technology. As the product printed on a 3D printer is quite precise, it is very helpful for prototyping or modelling. Take the process of making an object, whether for general use or strictly for a specific purpose: it’s quite another thing to observe the shape and ergonomics of a product on a computer screen during the design phase, or to hold it in your hands as a real object. In this way, it will be much easier to see if the design is really ergonomic, sits well in our hand, fits in with other objects, etc… Only when we are really happy with the design can we go to the next step, making the tool for mass production. Prototypes used to be made from wood, which is an inexact and time-consuming manual process. 3D printing technology therefore allows us to save a lot of time and, of course, money. Any design errors can be corrected on the model itself.
3D printing also allows us to produce highly complex, small-volume products and spare parts, of course where the technical specifications allow it. The latter is of course linked to the choice of materials in the printing process itself.
How?
How does a 3D printer work? Although there are several different methods available, the one thing they all have in common is that the product is created by applying the material in layers. To caricature a little: imagine a pear sliced very thinly. Each of these slices has a different shape, depending on where the cut is made. So when we sliced this pear into very thin slices, what we really got from a 3D object was a set of (almost) 2D objects, which when stacked on top of each other create an object in 3 dimensions, roughly the same way MRI works in medicine, where a powerful magnet “cuts” you into layers, and a computer assembles that set into a digital 3D image. 3D objects are made of (almost) 2D objects, which when stacked on top of each other create an object in 3 dimensions.
Recently, printers have really become accessible to practically anyone who wants to work in this field. There are currently two, slightly different technologies available, which I will describe below.
Filament printing (thermoplastic)
The basic principle of this printer is to inject molten plastic through a small hole (nozzle). For the system to work, this nozzle must be placed in a heated print head that moves in all three dimensions. In this heated head, the filament that the printer has wound in the form of a ‘string’ on the reel melts and changes to a liquid state. So the printer injects a thin layer of plastic onto the work surface (in some professional printers other materials can be used, such as powdered metal, etc., but these are applications that, for the most part, at least in amateur use, will not be encountered for the time being). After the first layer has been applied, the head moves up a few tenths of a millimetre and starts to apply the next layer, and so on to the final shape. While these printers are relatively precise, enabling highly complex products, they cannot match the detail of resin printing technology.
Resin printing
These printers also print layer by layer, using software that breaks the digital object into slices. However, the next stage is a slightly different way of doing it, because the basic material is also different. In this printer, a special epoxy resin is poured into a special container. Here too, there are different resins to choose from – depending on your needs. Directly underneath this container, which has a transparent bottom, is the LCD screen (practically touching this transparent bottom). The screen emits UV light and shows the current layer being printed. Because resin is sensitive to this type of light – he partly claims. The system moves the worktop upwards via a helical screw, so that the layers are stacked on top of each other. In this case, the whole object is moved upwards, with the first layer glued quite firmly to the work surface (to prevent it from falling into the resin container). The object “grows” from top to bottom – the opposite of filament printing, where the print head moves and the object is stationary. Resin printers are much more precise in detail and allow resolutions down to 0.03 mm. Which is satisfactory for mechanical engineering, dentistry, etc… They also have far fewer moving parts. The only downside of this technology is that it is a bit harder and dirtier to work with, as we have to wash all the containers and products with isopropyl alcohol at the end to remove the excess uncured resin. We also need to clean the rest of the tools and the container where the remaining resin is (which can be poured back into the packaging and stored). After cleaning, the product must be further and finally cured using a UV light emitting device.
In both technologies, we also have to take into account the support pillars, because in certain shapes (especially negative shapes) they support the layers that are not yet fully hardened, so that they do not deform under their own weight. Most printing software does this automatically, so we don’t have to worry about where and how many of these backers are needed…
Both technologies are quite revolutionary and allow us to print products that we have drawn in a 3D modelling software, or that we have obtained or bought online. But it all probably has a bright future, and with the current prices of printers, it has become affordable for everyone.
Tomaž Berčič
Here you can find links to the online shop for printers and consumables:
ELEGOO MARS 3 3D printer
Cleaner and UV hardener
Resins
