Yes, metal 3D printing is possible. There are several manufacturing processes that fall under the umbrella of metal additive manufacturing, but this article focuses on those that use layers of metal powder to build up and form complex structures that are difficult to create with other methods.
The metal 3D printing process involves sintering or melting metal powders directly, or combining them with a second material to be fed through a nozzle. It is used both for rapid prototyping and for the production of finished parts for the aerospace industry, mechanical engineering, tooling, etc.
Content
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What metals can be used in 3d printing?
What metals can't be used for 3d printing?
What processes can be used to 3D print metals?
Other Methods
Advantages and disadvantages
What is the purpose of metal 3D printing?
Is it expensive?
Conclusion
What metals can be used in 3D printing?
A wide range of different metals in powder form can be used to make parts using 3D printing. Titanium, steel, stainless steel, aluminium, copper, cobalt-chromium, titanium, tungsten and nickel-based alloys, as well as precious metals such as gold, platinum, palladium and silver are available as 3D printing powder.
These different metals have different properties, making them suitable for different applications. For example, stainless steel has excellent corrosion resistance, making it ideal for printing pipes, valves, and steam turbine parts.
What metals cannot be 3D printed?
Theoretically, any metal can be used for 3D printing, as long as it is available in the right powder form. However, materials that burn rather than melt at high temperatures cannot be safely processed by sintering or melting, but can be used when extruded through a 3D printing nozzle. Wood, fabric and paper cannot be 3D printed with these processes.
Sintering (forming into a mold at high temperature and extremely high pressure) can also be used to create solid products from metal powders, and in the case of metals with a very high melting point, sintering is the only reliable method for producing products from these materials.
What 3D printing process can be used to 3D print metals?
As mentioned above, there are several technologies for 3D printing metals. Powder bed fusion methods, which include direct metal laser sintering (DMLS), selective laser melting (SLM), and electron beam melting (EBM), are the most widely used metal additive manufacturing methods:
Direct Metal Laser Sintering (DMLS)
In this widely used method, a laser sinters metal powder layer by layer to form an object. At the same time, the metal does not actually melt and is used to create prototypes and manufacture finished parts, including medical devices and tools.
Selective laser melting (SLM)
This process involves the use of a laser to melt the material at the desired locations in the powder layer in an inert gas environment. In this way, objects are created layer by layer with parameters similar to those obtained by casting. SLM is often used for the production of aluminum and titanium parts, including for the medical, automotive and aerospace industries.
Electron Beam Melting (EBM)
This process is similar to SLM, only an electron beam is used to melt the material rather than a laser. EBM is considered faster and more accurate than SLM and is often used to produce cobalt and titanium products. EBM is widely used in the aerospace industry for the manufacture of parts including engine components.
Other methods:
There are other technologies that can be or are already being used for metal 3D printing, although they are not as widely used as DMLS, SLM or EBM:
Laser metal deposition (LMD)
LMD is used in the aerospace, automotive, and medical industries, creating objects by layering heated metal onto a metal substrate. LMD allows you to use different materials to create an object and is faster than other methods.
Selective laser sintering (SLS)
Similar to DMLS, this process also uses a laser to sinter powdered materials. It is used to make products from a wide range of materials, including metal. However, these days it is mainly used for sintering plastics such as polyamide and nylon.
Jet application of binder
This process uses a special liquid to bind the powder material and is less expensive than DMLS, SLM or EBM. The accuracy and strength provided by this process is not ideal, so post-processing is often required. Hot isostatic pressing can be used to increase the strength and hardness of the finished object, but this increases costs. Injection molding is commonly used to make large scale and complex prototypes.
Injection molding
This combination of injection molding and 3D printing is widely used to make small components in industries such as medical and defense. The process takes place by mixing metal powder with thermoplastic and wax binders. This mixture is heated until the binder melts and coats the powder, which is then granulated into granules. These pellets are heated and introduced into the cavity to form the object, after which the binder material is removed, usually by solvent extraction. The part is then sintered, evaporating the remaining binder and compressing the object into a dense, solid material. The object can then be processed as required.
What are the advantages and disadvantages of metal 3D printing?
There are a number of advantages and disadvantages associated with 3D metal printing:
Advantages
Easily manufacture complex shapes faster than traditional manufacturing methods
Cheaper than many traditional production methods for some parts
Ability to produce precise and highly detailed objects
Since parts can be included during assembly, this saves time and money compared to more traditional manufacturing methods.
Complex shapes can be created to create lighter objects without compromising strength, making metal 3D printing an ideal solution for the automotive, aerospace, and space industries.
Very little material waste
Multiple parts of a complex assembly can be combined into one component, reducing the number of parts and assembly cost.
Flaws
Parts destined for traditional production are being produced slowly, making high-volume production uncompetitive on cost alone
Powdered metal materials are more expensive than non-powdered materials (e.g. billet or rod)
Metal 3D printers can be expensive
May require surface treatment and post-processing of 3D printed parts
Lower accuracy and tolerances compared to dedicated CNC machining
Heat treatment may be required to reduce internal stresses in a 3D printed part or achieve maximum metal strength.
Designing 3D metal parts can be complex and requires the services of professional CAD engineers
The size of the parts is limited by the volume of the 3D printer.
What is the purpose of metal 3D printing?
The advantages and disadvantages of the process provide insight into the purpose of 3D printing in metal, showing that it is well suited to making relatively small, complex parts, including prototypes. It can also facilitate tooling for traditional manufacturing techniques, reducing costs and reducing lead times.
Combining the flexibility of 3D printing with the mechanical properties of metal, this technology has found applications in a variety of industries, from coolant-lubricated inserts through lightweight aerospace structures to complex parts used in challenging environments. Typical applications include full-featured prototyping, production tooling, tooling for molds or inserts, housings, ducting, heat exchangers, and heatsinks.
Of course, different metals allow you to print different objects, for example:
Stainless Steel: Ideal for objects that will be in contact with corrosive liquids, water or steam due to its excellent corrosion resistance.
Bronze: pump impellers and marine propellers, lamps and more decorative items such as vases
Gold: Can be used for jewelry printing
Nickel: Can be used to print turbine engine parts or even coins
Aluminum: Ideal for metal objects, especially where lightening is required, such as aircraft airframe parts.
Titanium: Capable of producing very strong, precise parts such as medical implants (such as hip joints) and other hard fixtures and objects.
Is 3D metal printing expensive?
Different 3D printing technologies use different solutions for industries with different materials and complexity, which means that the cost of metal 3D printing can vary significantly. However, most of the costs are for 3D printing machines, which can be a significant part of the total production costs, along with labor, materials, preparation and post-processing. The need for high quality powdered materials also adds to the cost of 3D printing metals as they are more expensive than non-powdered metals in the same quantities.
As mentioned, printer prices can be high, with costs of several or even hundreds of thousands of pounds, although these prices are comparable to a high quality CNC machine of a similar size. As technology improves and the market size increases, the price of 3D printing machines is expected to decrease.
In addition to the cost of materials and the printer, there are design costs for the objects that are created. This may require purchasing specialized software or hiring CAD engineers with specialized knowledge of 3D printing. Of course, there are other labor costs involved in operating and maintaining machines.
Finally, there are costs associated with the post-processing of printed parts. This may include cleaning, heat treatment, removal of load bearing structures, and surface coating.
Conclusion
Metal 3D printing, or additive manufacturing, makes it possible to produce parts with almost the same strength as ordinary metal objects.
Although this method can be expensive and not very suitable for replacing traditional production for high volume production of standard products, it is ideal for making small, complex products. Metal 3D printing is also helping to lighten parts used in industries such as aerospace and automotive.