3D printing is considered the most complex technological achievement and an important area of additive manufacturing. Thanks to three-dimensional printers, new opportunities are opening up in all sectors of the economy. It is believed that in the future they may even supplant traditional methods of production (forging, casting, etc.). In this article we will consider what 3D printing with metals and its main technologies are.
What is a 3D printer for metal
These are special machines that allow the production of metal objects or coating finished products. Such a printer "grows" a physical object in layers. That is, first, on a computer in the design system, a virtual model is created in three dimensions, divided into digital layers. After the object is put into print, the head of the 3D printer starts to squeeze out liquid metal or pour powder onto the printing platform, forming the first layer. Then the machine applies a second portion of metal and so on.
A 3D metal printer allows you to create a wide range of products and, thanks to modern technology, can compete with classical metal production methods.
What can I print with a 3D printer?
This printer is a universal invention that can be used by both professionals and ordinary enthusiasts. Metal printers can be used for the manufacture of non-standard objects, mechanical parts, jewelry. They also allow you to create metal products that simulate hand forging. And for this, additional devices and mechanisms are not needed.
An industrial 3D metal printer can even print a rocket engine. At the same time, it will practically not differ from a product made by the traditional method. Thus, the metal printer enables the modern person to create any objects.
3D Metal Printing Technologies
To date, the manufacture of metal products is carried out by two technologies: laser and inkjet printing. They imply a gradual and accurate layering of the metal, as a result of which the intended figure should be obtained. At the same time, engineers developed several cultivation methods.
Inkjet 3D printing
The manufacture of metal products by inkjet printing is one of the oldest methods of additive manufacturing. 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 is that the 3D inkjet printer allows you to print objects from any material that can be processed into powder. During printing, the crushed raw materials are bound by polymers. Due to this technological feature, finished products cannot be considered completely metal.
In addition, it is possible to convert the resulting composite models into all-metal ones. For this, thermal smelting or burning of polymers and sintering of powdered metal are used. Such metal products are not durable because they have a porous structure. Strength can be added by impregnation with 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 industries.
Lamination method
3D printing by lamination involves applying thin sheets of metal formed by laser or mechanical cutting to the platform and gluing them to obtain a three-dimensional model. This method allows you to use even metal foil as a consumable. Laminated objects do not have metal strength, since their integrity is based on bonding bonded sheets.
The advantage of this technology is the relative cheapness and the ability to create a variety of objects that are identical with all-metal products. Most often, lamination printing is used to create layouts.
Deposition
This 3D printing method is based on the use of alloy materials. The extruders available in the printer cannot withstand 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 printer for this type of metal prints objects that in appearance cannot be distinguished from an all-metal product. But the physical properties of such objects are significantly worse. Therefore, layer-by-layer deposition is used exclusively for creating models, souvenirs, and interior items. Now engineers are looking for industries where it is permissible to apply this production technology. So, metal-filled thermoplastic can be used to print electronic circuit boards.
Selective laser and direct sintering
Selective laser sintering of metals allows you to work not only with durable material, but also with thermoplastic. Here, the creation of three-dimensional objects occurs using laser systems by sintering a metal powder. Quite often, to lower the power of laser emitters, a more fusible coating is applied to the metal material. In such cases, to increase the strength of the finished products requires additional sintering and impregnation with metals.
A variation of the described method is direct laser sintering of metals. This technology is focused on working with pure metal in powder form. To achieve this, the 3D printer has special sealed chambers filled with inert gas. Also, the printing machine applies heating of the consumable to the temperature at which it melts, but does not boil yet. This allows you to reduce printing time and save on the power of laser systems.
Laser sintering printing is done in layers. On the working platform, the machine applies a thin layer of heated powder, the particles of which are sintered between themselves and with the previous layer. The laser beam constantly changes its direction using a system of mirrors.
Laser sintering makes it possible to create complex structures without additional supports. Thus, this technology is used to create high-precision parts that do not require subsequent machining, as well as to produce solid models of a level of complexity that cannot be achieved by conventional casting.
Laser sintering allows you to work with steel, nickel alloys, titanium, precious metals, etc.
Selective laser and electron beam melting of metals
Although the models obtained by laser sintering of metal are of high quality, they have limited application. The porous structure of finished objects reduces their strength. Such products are unsuitable for industrial use, and are more used to create models and prototypes. To produce robust and load-resistant models, engineers converted direct laser sintering technology to laser smelting. It is based on a strong heat treatment of a metal powder to obtain a homogeneous object. Objects printed in this way, in fact, do not differ in mechanical and physical properties from analogues made by traditional methods.
In parallel with this technology is applied electron beam melting. It makes it possible to create objects with the same accuracy and resolution, but has certain advantages. So, a 3D printer for metal of this type is equipped with electron guns instead of electromechanical mirror systems. This allows the machine to operate at relatively high speeds, which increases productivity without significant complications of the process. This technology is an excellent alternative to traditional industrial production, where additional equipment is used (furnaces and casting molds).
Printers for laser and electron beam melting are mainly used for the production of parts for jet engines and gas turbines, orthopedic prostheses.
Direct laser additive construction
3D printer for metal direct laser construction is used to repair finished products. The technology of such a machine is based on the principle of spraying particles of metal powder on damaged parts of an object and their melting with a laser. This method is characterized by narrow specialization and is used exclusively for industrial purposes.
This type of printhead moves in three planes and rotates around a vertical axis. Thus, it works from any angle.
Similar machines are used to repair complex mechanisms and bulky products. For example, to repair aircraft engines.
The cost of a 3D printer for metal
Today, the market has a wide range of machines that allow you to create three-dimensional metal objects. Their cost depends on the brand and printing technology. So, an industrial 3D metal printer that can print an engine costs tens of thousands of US dollars. More affordable cars can be bought much cheaper, but the quality of the products will be worse. To solve this problem, engineers are developing a 3D printer for metal, the price of which will be much lower when fully operational.