Today, no one will be surprised by the technologies that have stepped from the books of science fiction. Three-dimensional printing is becoming more popular. Nowadays, there are a lot of 3D printers, and accordingly, there are also many ways to create models with their help. However, in principle, all printers are based on one of three different technologies.
First, there is the so-called stereo lithography (SL or SLA). Inside the printer is placed bath, which is liquid photopolymer. Photopolymers are plastics or resins that harden when exposed to light. Printers usually work with acrylic, epoxy or vinyl resin. A laser beam moves along the surface of the resin, and where it touches it, the resin hardens. In the photopolymer pool, there is a platform, which after each solidification goes down a little (deeper into the bath).
Thus, the object is printed in rows, like text in a regular printer. After complete curing of the model, it is characterized by high strength and chemical resistance. The advantage of this method is the accuracy of the transfer: the printer can print very clean even small micrometric structures.
The second technology of the 3D printer is selective laser sintering (SLS). To understand how this works, imagine a vertical pipe with a moving platform in it. Plastic, molding sand with a plastic coating, metal or ceramic powder are distributed on the platform in a thin layer using a roller. Then the laser beam begins to move along the platform, heating certain points in the powder so that they merge and form the object.
The third way is classic. It is called fusion modeling (FDM). In this process, each new product layer is formed from liquid plastic, which is passed through an extruder (a programmable device that gives it a certain shape) and then immediately cured by a laser. Then the cured layer is displaced downwards, the extruder gives shape to a new layer, and it is fused on top of the previous one, and so on.
How are models created for printing?
First, a 3D model of the object is created using the CAD program and saved in a special STL format. The STL file is then loaded into a cutting program for a printer, for example, Cura or Slic3r. The cutting program allows you to set the physical properties of the model, such as the density of the filling or the use of supporting structures.
The program converts a 3D model into a G code. It contains instructions for the extruder, according to which it must shape each layer of the model. The code is loaded into the printer, the device starts up, and printing begins.
What materials are used in 3D printing?
3D printing is carried out using various types of plastic. It comes in the form of threads wound on large spools. The thread is charged into the printer, which draws in and melts it so that the plastic becomes liquid and can be shaped.
Polylactide (PLA) is most commonly used in printers. This is plastic, which is obtained from renewable sources – for example, from corn starch. It is water repellent and also safe for the manufacture of containers for food. In addition, it is flame resistant and resilient to UV radiation. The biggest advantage is that there is no unpleasant smell when printing.
High-impact polystyrene (HIPS) is often used to print bearing structures in ABS plastic models. This plastic has a high impact strength and hardness.