1. Material extrusion

The principle is to use a moving extrusion head to locally deposit a filament of plastic or composite material. Heated to several hundred degrees, the extruded material, in semi-solid form, adheres to the surfaces in contact and rapidly solidifies. The material is first deposited on a printing plate regulated at a temperature of the order of a few tens of degrees to form a first layer. The next step is to deposit filament again on top of the previous layer, as illustrated in figure 1 . By iteration, the accumulation of superimposed layers gives shape to the part. The raw material used is either wire or granules. At the end of the printing process, the part is separated from the printing plate and can undergo further...