3D printing is considered the most complex technologicalachievement and an important direction of additive production. Thanks to three-dimensional printers, new opportunities are opening up in all sectors of the economy. There is an opinion that in the future they can even displace traditional production methods (forging, casting, etc.). In this article we will consider what is 3D printing with metals and its main technologies.
What is a 3D printer for metal
These are special machines that allowproduce metal objects or apply coating to finished products. Such a printer "grows" a physical object layer by layer. That is, first on the computer in the design system, a virtual model is created in three dimensions, divided into digital layers. After starting the object in print, the 3D printer's head starts to squeeze out the liquid metal or pour the powder onto the printing platform, forming the first layer. Then the machine applies a second portion of metal and so on.
3D-printer for metal allows you to create a large range of products and, thanks to modern technology, can compete with classical methods of metal production.
What can I print with a 3D printer?
This printer is a universal invention,which can be used by both professionals and simple enthusiasts. Metal printers can be used for manufacturing non-standard objects, mechanical parts, jewelry. They also allow the creation of metal products simulating hand forging. And for this, additional devices and mechanisms are not needed.
An industrial 3D printer for metal caneven a rocket engine. In this case, it will not practically differ from the product manufactured by the traditional method. Thus, the metal printer enables a modern person to create any objects.
3D printing technologies for metal
To date, the manufacture of products frommetal is carried out by two technologies: laser and inkjet printing. They mean gradual and accurate layering of metal, as a result of which the intended figure should be obtained. At the same time, engineers have developed several ways to grow.
Inkjet 3D printing
Manufacture of metal products with inkjet printingis one of the oldest ways of additive production. It allows the best way to use metals as consumables. But this technology is applicable only in the case of creating a composite model. The fact that the inkjet 3D printer allows you to print objects from any material that can be processed into powder. During printing, the ground raw materials are bound by polymers. Because of this technological feature, finished products can not be considered completely metal.
In addition, it is possible to convertobtained composite models in all-metal. For this, thermal smelting or burning of polymers and sintering of powdered metal are used. Such metal products are not durable, since they have a porous structure. Add strength can be due to the impregnation of another metal. For example, a steel object will become more durable if it is impregnated with bronze.
This method of creating products is mainly used in the souvenir and jewelry industry.
3D printing by laminating meansdrawing on the platform of thin sheets of metal, formed by laser or mechanical cutting, and their gluing to obtain a three-dimensional model. This method allows us to use even metal foil as an expendable material. Laminated objects do not have metal strength, because their integrity is based on the gluing of bonded sheets.
The advantage of this technology isrelative cheapness and the ability to create a variety of items that are identical with all-metal products. The most common printing lamination is used to create mock-ups.
This method of 3D printing is based on the use oflight-alloy materials. Extruders available in the printer are not capable of withstanding high temperatures. Therefore, it is almost impossible to create objects from pure metal and alloys. Thus, the developers of consumables began to produce special composite raw materials. An example of such a solution is a material consisting of thermoplastic and bronze powder.
A metal printer of this type prints items,which in appearance can not be distinguished from an all-metal product. But the physical properties of such objects are much worse. Therefore, layer-by-layer fusing is used exclusively to create mock-ups, souvenirs, and interior items. Now, engineers are looking for industries where it is permissible to use this production technology. Thus, thermoplastic with a metal filler can be used for printing electronic boards.
Selective laser and direct sintering
Selective laser sintering of metals allowswork not only with durable material, but also with thermoplastic. Here the creation of three-dimensional objects occurs with the help of laser installations by sintering a metal powder. Quite often, to reduce the power of the laser emitters on the metallic material, a more low-melting coating is applied. In such cases, to increase the strength of finished products, additional sintering and impregnation with metals are required.
A variation of the described method is directlaser sintering of metals. This technology is focused on working with pure metal powder type. To realize this goal, there are special sealed chambers filled with inert gas in the 3D printer. Also, the printing machine uses the heating of the consumable material to the temperature at which it melts, but does not boil yet. This allows you to reduce the printing time and save on the power of laser installations.
Laser sintering occurslayers. On the work platform, the machine applies a thin layer of heated powder, the particles of which are sintered together and with the previous layer. The laser beam constantly changes its direction with the help of a mirror system.
Laser sintering makes it possible to createComplex designs without additional supports. Thus, this technology is used to create high-precision parts that do not require subsequent machining, as well as for the production of integral models of a level of complexity that can not be performed with conventional casting.
Laser sintering allows working with steel, nickel alloys, titanium, precious metals, etc.
Selective laser and electron beam melting of metals
Although the models obtained by laser sinteringmetal, are of high quality, they have limited application. The porous structure of the finished objects reduces their strength. Such products are of little use for industrial applications, but are more used to create mock-ups and prototypes. For the production of durable and load-resistant models, engineers converted direct laser sintering technology into a laser melting method. It is based on a strong thermal treatment of the metal powder to obtain a homogeneous object. Objects printed in this way do not actually differ in mechanical and physical properties from analogs manufactured by traditional methods.
In parallel with this technology is appliedelectron beam melting. It allows you to create objects with the same accuracy and resolution, but has certain advantages. So, a 3D printer for metal of this type instead of electromechanical mirror systems is equipped with electronic guns. This allows the machine to operate at relatively high speeds, which improves performance without significant process complications. This technology is an excellent alternative to traditional industrial production, where additional equipment (furnaces and molds) is used.
Printers for laser and electron beam melting are mainly used for the production of parts of jet engines and gas turbines, orthopedic prostheses.
Direct laser additive construction
3D printer for metal direct laserconstruction used to repair finished products. The technology of such a machine is based on the principle of spraying particles of a metal powder onto damaged parts of an object and melting them with a laser. This method is characterized by a narrow specialization and is used exclusively for industrial purposes.
The print head of this type of printer moves in three planes and rotates about the vertical axis. So, it works at any angle.
Similar machines are used to repair complex machinery and large-sized products. For example, to repair aircraft engines.
The cost of 3D-printer for metal
Today the market has a large assortment ofmachines, allowing to create three-dimensional metal objects. Their cost depends on the brand and printing technology. So, an industrial 3D printer for working with metal, on which it is possible to print an engine, costs tens of thousands of US dollars. More affordable machines can be bought much cheaper, but the quality of products will be worse. To solve this problem, engineers are developing a 3D printer for metal, the price for which will be much lower when fully operational.