Additive manufacturing is generally based on the deposition, layer by layer, of selected, very fine metal powders, produced through atomizers. The metal powder is melted or sintered by a laser following the design of the predefined digital model.

Below are the main technologies currently used for additive 3D printing.

DED –Direct Energy Deposition
Direct Energy Deposition (DED) technology consists of a nozzle mounted on an arm that deposits molten material onto a surface. It mainly uses metal powders and, alternatively, metal wire. As its limitation, it has a poor surface quality.

EBM –Electron Beam Melting
It is an additive manufacturing technology in which a high energy source, composed of a suitably concentrated and accelerated beam of electrons, strikes the metal powder causing it to melt completely. There is more performance than the DED regarding the surface finish and the complexity of the forms that can be created.

MBJ –Metal Binder Jetting
In this technology, the metal powder is joined with a binder and is subsequently subjected first to a debinding process and finally to a sintering treatment.

SLM –Selective laser Melting
In the SLM process, the laser beam sectionally strikes the newly deposited layer of metal powder. The energy, which manages to be absorbed by the powder itself, generates a volume of molten metal that solidifies very quickly. Of all the techniques illustrated, it is the one with the best performance in terms of surface finish, complexity of shapes, density and mechanical properties. Suitable for niche productions with more limited quantities.

Main materials used
 

In additive 3D printing, one of the most commonly used metals is pure titanium (Ti64 or TiAl4V), by virtue of its characteristics of versatility, strength and lightness. It is widely used in aerospace, biomedical and motor sport sectors.

Another widely used material is SS316L stainless steel (EN 1.4404), a low-carbon steel alloy, extremely resistant to corrosion and with excellent strength. Stainless steels differ according to the percentage of loss of the elements that form the alloy. For example, 316L (one of the most common), is formed by a low percentage of carbon (less than 0.03%), by a percentage of chrome between 16.5 and 18.5 %, from nickel between 10.5 and 13.5% and molybdenum between 2 and 2.25%. 3D printed 316L stainless steel has high ductility and good thermal properties and can be used for technical applications for the mechanical, medical or engineering sectors, for food use, and for making parts of watches or jewellery.

Another material used in 3D printing is Inconel (registered trademark of the US company Special Metals Corporation): it refers to the family of super alloys with austenitic structure based on nickel-chrome. Inconel is an alloy, mainly based on nickel (48% -72%) and chrome (14% -29%). It has excellent resistance to oxidation at high temperatures and corrosion.

Copper and its alloys offer an excellent combination of electrical conductivity, thermal conductivity, high rigidity, even at high temperatures, and high resistance to corrosion. These properties make these materials ideal for the production of sliding parts or those requiring great resistance to wear and for use in the electrical engineering sector (e.g. robotic grippers, heat exchangers, welding discs, etc.).

By virtue of its recognized qualities of lightness, strength and flexibility, aluminium and its alloys (in particular AlSi10Mg) are also one of the metals used in 3D printing. Due to its characteristics, it has considerable applications in the automotive, aerospace and automation sectors, in particular for the construction of pipelines, engine parts, production tools and moulds, both for prototyping and manufacturing.

New great prospects are opening up for industry and design with metal 3D printing, even in sectors related to more traditional production systems: so is the future already here?

We at UNIQ∙Ǝ! believe so! Do you?