In recent years, not only home 3D printers using resin materials have attracted attention, but also "metal 3D printers" that use metal materials. As this is a method of forming one layer at a time, it can be applied to shapes that are difficult to process by other methods. The above solution is mainly introduced in the aviation and medical industry and takes advantage of the characteristics of 3D printers. In this article, we will explain the advantages and disadvantages of metal 3D printers, comparing them with fused deposition modeling 3D printers that use resin materials. We will also present the industries that can actually benefit from this.
What is a 3D metal printer?
A 3D metal printer is a device that shapes metal materials, such as titanium, aluminum, and stainless steel, based on 3D CAD data. Generally speaking, 3D printers that use resin as a modeling material are widely used in the industry, however, the current situation is such that there are few companies that have introduced expensive 3D metal printers.
How does a 3D metal printer work?
Based on the cross-sectional data created using dedicated software, 3D metal printers create objects of any shape, combining metal materials layer by layer and repeating lamination. Unlike the cutting process, which shaves off a bulk of metal, or the forging process, which shapes it under pressure, 3D metal printers are designed to layer and form metal materials, allowing them to handle complex shapes such as mesh structures and designs hollow inside. Another issue is that metal parts can be created without preparing a special mold - similar to casting.
What are the methods of 3D metal printing?
There are various types of 3D printers for metal. The most popular methods they perform are:
- powder bed method,
- directed energy deposition method,
- hot lamination method,
- binder jetting method,
How does the powder bed method work in a 3D printer?
It should be noted here that the properties of the object formed by each heat source are different.
For example - using a laser, compared to the electron beam method, it is possible to create a model with a smooth surface, but it is difficult to apply it to materials that do not absorb the beam. Moreover, the metal powder used should have a high degree of sphericity and ease of flowability, so that it can be accurately distributed. Therefore, the commonly used raw material is spherical powder obtained by the "gas atomization" method, in which an inert gas is used.
Directed Energy Deposition Method
In the method of directed energy deposition, the modeled product is produced by supplying powder or wire, melting it with a laser or electron beam, and depositing it. Generally, powders are used and delivered with an inert gas. Since the supplied material is used for the model without waste, it is a production process with minimal material loss and good efficiency. The above method is most often used for repairing metal parts. However, since it allows for the formation of large parts with simple shapes, the application of this scheme in the field of aviation and astronautics is being considered. The advantage of using this device is that the surface can be machined during formation, which eliminates the need for final processing.
What does the hot lamination method involve?
The hot lamination method, also known as "material extrusion", is a molding method in which metal powder is introduced into thermoplastic resin, and then laminated during melting. You can then freely shape and control it with the thermoplastic resin, which softens when heated. However, since the resin remains after molding, it is removed in a process called degreasing. After sintering the degreased shape and solidifying the metal powder, the shaping is completed. Since the resin is removed during sintering, the gap disappears, and the volume shrinks by about 20%. Therefore, it is important to design CAD data taking into account the size of the shrinkage and to create a model of the appropriate size. The fused lamination method was traditionally used as a 3D printer for resin.
What is the flux stream method?
The binder jetting method is a process in which a liquid binding agent "binder" is sprayed from a nozzle onto metal powder. After spraying and solidifying the binder for each layer, the modeling plate is lowered and powder is placed there again. This process is repeated and finally sintered in a high-temperature furnace or heater to remove the binder. At this time, the model shrinks by about 20%, so the change in the volume of the material should be taken into account during modeling. Items made by the binder method usually have a lower density than those made by the powder bed method, which poses a problem in practical application. Currently, it is a forming method used for small parts with fine shapes.
What are the advantages of metal 3D printers?
Metal 3D printers have an advantage over conventional processing methods, such as cutting, casting and forging, and moreover, there are high expectations for their further technological development in the future.
Metal 3D printer:
- Can print metal parts with excellent strength and durability.
- Offers short-term production of prototypes and small-batch products.
- Prototypes can be easily produced due to cost reduction.
What are the disadvantages of 3D metal printers?
3D metal printers have various advantages, but they are not universal devices. This is because there are three disadvantages that we need to mention:
- Using the equipment requires knowledge of modeling.
- The initial cost is expensive.
- 3D metal printers are expensive to operate.
Good to know
Thanks to 3D metal printers, materials can be stacked and shaped, allowing even complex shapes that are difficult to cut out to be produced. During cutting, it is difficult to install a cooling water pipe inside the mold, as there is a limitation on the area that can be cut by the tool. However, with 3D metal printers, even hollow structures can be formed and products that cannot be produced by conventional machining can be created. Such equipment is also suitable for "difficult to machine materials", which are too complex to cut. For example - until now, in the aviation industry, parts made of titanium alloys were produced by casting and machining. However, titanium alloy is a difficult to machine material, so 3D metal printers, which do not require cutting, began to be used and were successfully introduced for practical use.
3D Printers in Medicine
3D metal printers are also suitable for products in the medical industry. It is important in this case to finish artificial bones and prostheses in a shape adapted to the skeleton and shape of each patient's teeth. The traditional casting process requires time and effort to remodel the mold for each patient. If you use a metal 3D printer, you can change the shape of the product simply by correcting the CAD data, which allows you to quickly shape it. In this way, 3D metal printers are a manufacturing process suitable for production with high diversification and low volume.
Examples of 3D metal printers used in industry
3D metal printers are used in the following industries due to their numerous advantages:
- Medical field.
- Aviation
- Automotive industry.
Medical field
In the medical industry, 3D metal printers are starting to be effectively utilized. This is because it is necessary to provide "artificial bones" and "prostheses" that are designed in an optimal shape for the patient. 3D metal printers can freely control the shape using CAD data, making it possible to create an optimal model for each patient. For this reason, even in Japan, more and more companies and research groups are obtaining "pharmaceutical approval (consent required for production and marketing)" for artificial bones made by 3D metal printers.
Aviation
3D metal printers can also be used in the aviation industry. Metal 3D printers are suitable for turbine blades and combustion nozzles used in aircraft engines, which have complex shapes that are difficult to cast and cut. GE Aviation, an American aircraft engine manufacturer, managed to model a combustion nozzle that is actually mounted in the engine. Conventionally, over 20 parts were assembled, but with the use of metal 3D printers, the product can be integrated.
Automotive Industry
Cars use a large number of titanium materials, which are difficult to cut, and parts with complex shapes. Therefore, the automotive industry is a field that can easily benefit from the advantages of 3D metal printers. The Italian car manufacturer Bugatti produces a model consisting exclusively of elements that are made using a 3D metal printer. However, this model is a supercar limited to 40 pieces and has not been introduced into serial production. 3D metal printers will be used more frequently if the challenges associated with mass production can be overcome.
How to use a metal 3D printer and cut?
Cutting with a machining center or NC lathe is characterized by excellent machining accuracy. Therefore, if the shape can be easily produced - use classic cutting. However, if the product shape is complex, keep in mind that there are cases where it is difficult to process because there is no possibility of inserting a knife. Moreover, it is difficult to cut materials resistant to the blade, such as "titanium", which easily ignites chips during cutting, and "stainless steel", in which molten metal easily adheres to the blade. If the product has a complex shape and cannot be produced or if you want to process materials difficult to cut, it is better to use a 3D printer for metal. Additionally, in the case of products requiring multiple cutting processes, the use of a 3D printer for metal can shorten the production process and produce them in a short time. If you want to prevent material losses, it is a good idea to use a metal 3D printer. This is due to the fact that during cutting there are material losses due to the removal of the resulting chips, and in practice, 3D printers for metal use only the necessary amount of materials, which reduces waste of raw materials and leads to improved efficiency.
Summary
3D metal printers are mainly used in situations where cutting, casting, and forging are difficult to perform, as well as for products with complex shapes. However, since the initial cost and operating cost are very high, there is a problem that it is not easy to introduce compared to a 3D printer using the fused deposition modeling method. Either way - it is expensive and complex equipment, but if we find a niche where we can use it, it is worth doing.