3D printing with metal is now an established production process. It allows the individual production of highly complex structures. Inert gases play an important role here.
The technical term for 3D printing is "additive manufacturing" because the workpieces are created by adding material instead of removing it. This is fairly easy with plastics, where the process is very widespread. Additive processing of metallic materials is much more complicated and time-consuming in comparison. This starts with the starting material. "Among other things, fine powders are used in metal 3D," explains Dr. Dirk Kampffmeyer, Messer specialist for welding and additive processes. "They have to meet very high-quality standards in terms of alloy and grain size, which requires correspondingly high-caliber technologies in production."
Powder bed and laser beam
For 3D printing a powder bed is prepared from the granular base material. As with plastic the material is liquefied at certain points. The first layer of the component is melted from a thin layer of powder by heating the metal with a guided laser. The next layer of powder is then applied and this is also melted along the contours of the component. In this way, the desired product is created layer by layer using "Powder Bed Fusion-L" - the L stands for laser.
Metal powders are also suitable for another additive process: powder spraying, which is very similar to welding. Here, the powder is transported from a carrier gas into a laser head, where it collides with a laser beam and melts. Driven by the gas pressure the molten material reaches the workpiece; the computer-controlled movement of the head gives it the desired shape. Existing components can also be supplemented and modified in this way. Experts call this type of additive process Direct Energy Deposition (DED). In addition to the DED-laser variant, there is also DED-arc, which uses an electric arc as an energy source.
Easier with wire
However, there is another alternative to metal powders. It is much easier and cheaper to use wire as a material supplier instead of powder. This does not allow quite as fine a structure to be produced, but for most products the results of the wire-based supply are sufficient. There is a special technical term for the particularly frequently used combination of wire and arc: Wire Arc Additive Manufacturing (WAAM).
Additive processes take time. Depending on the size it can take hours or days before a component is ready. "3D printing with metal is, therefore, not a viable option for mass production," emphasizes Dr. Kampffmeyer. "But when it comes to high-quality parts with complex geometries, things get very interesting. For example, you can produce turbine blades with intertwined cooling channels in a single pass, which would not have been possible with conventional processes."
Spare part from the print file
In fact, alongside the aircraft industry, power plant technology is one of the most important areas of application for additive manufacturing. For the latter, it also solves a fundamental dilemma: aviation authorities and airlines require manufacturers to keep certain spare parts in stock for up to 30 years. Over such a period, too many of some parts are inevitably produced and too few of others, both of which result in high follow-up costs. For non-safety-relevant parts, it is now sufficient to save a print file. In this way, it is possible to produce additional parts as required at low cost. Train manufacturers also make use of this as similar rules apply to the railroads when it comes to stocking spare parts
Another typical field of application for metal 3D is profile shapes for truck tires. Numerous tire manufacturers rely on flexible additive manufacturing in order to be able to produce the templates cost-effectively, even for smaller product series. The process is ideal for products that by definition only exist once. These include, for example, individual implants, such as for dental prostheses or artificial joints, which are precisely adapted to the patient's anatomy.
”When welding, the aim is usually to achieve the deepest possible penetration in order to create a very strong bond. On the contrary, additive processes are about the most delicate layering possible. However, the levers for achieving one or the other are the same.”
Dr. Dirk Kampffmeyer, Specialist for Welding and Additive Processes at Messer
Prevent oxidation
Whether powder or wire, laser or electric arc, the molten metal always needs protection from atmospheric influences and especially from oxidation. Additive manufacturing is also related to welding in this respect. "When welding, the aim is usually to achieve the deepest possible penetration in order to create a very strong bond," explains Dr. Kampffmeyer.
"On the contrary, additive processes are about the most delicate layering possible. However, the levers for achieving one or the other are the same. The expertise in welding processes that we have built up over decades can, therefore, also be used for 3D printing with metal." In this field, Messer not only offers gas mixtures that are perfectly suited to the respective production process, but also provides comprehensive support to users in optimizing their processes.
For more than 125 years, Messer, the today’s world's largest privately owned company for industrial gases, medical gases, specialty gases, and gases for electronics, committed to its guiding principles of safety, focus on customers and employees, responsibility for our society, sustainability, trust, and respect. Messer's Gases for Life and patented gas applications are essential for environmental protection, climate protection, decarbonization, and innovation.
