3D printing is a versatile technology that can create objects from various materials, but it also has some limitations. Some materials cannot be 3D printed because they are too hard, too soft, too brittle, too toxic, or too complex. In this article, we will explore some of the materials that cannot be 3D printed and why.
Metals are one of the most common materials used in 3D printing, especially for industrial applications. However, not all metals can be 3D printed easily or effectively. Some metals, such as steel, aluminum, and titanium, can be 3D printed using methods such as selective laser melting (SLM), direct metal laser sintering (DMLS), or electron beam melting (EBM). These methods use a high-powered laser or electron beam to melt and fuse metal powder layer by layer. However, these methods are expensive, require high temperatures and pressures, and produce parts that may have defects or residual stresses.
Other metals, such as gold, silver, and copper, are more difficult to 3D print using these methods, because they have high thermal conductivity and reflectivity, which means they dissipate heat quickly and reflect the laser or electron beam. This can result in poor melting, incomplete fusion, or overheating of the metal powder. To overcome these challenges, some 3D printers use a binder jetting method, which deposits a liquid binder onto a bed of metal powder, and then uses a furnace to sinter the parts. However, this method also has drawbacks, such as lower resolution, lower strength, and higher porosity.
Some metals, such as tungsten, chromium, and molybdenum, are almost impossible to 3D print using any of these methods, because they have extremely high melting points, hardness, and density. These metals require very high temperatures and pressures to melt and fuse, which are beyond the capabilities of most 3D printers. Moreover, these metals are prone to cracking, warping, and oxidation during the 3D printing process.
Ceramics
Ceramics are another class of materials that are widely used in 3D printing, especially for biomedical, aerospace, and electrical applications. Ceramics have high strength, hardness, wear resistance, and thermal stability, which make them suitable for many demanding applications. However, ceramics also have some limitations that prevent them from being 3D printed easily or effectively. Some ceramics, such as alumina, zirconia, and silicon nitride, can be 3D printed using methods similar to metals, such as SLM, DMLS, or EBM. However, these methods also require high temperatures and pressures, and produce parts that may have defects or residual stresses.
Other ceramics, such as porcelain, glass, and clay, are more difficult to 3D print using these methods, because they have low thermal conductivity and high viscosity, which means they do not melt and flow easily. To overcome these challenges, some 3D printers use a stereolithography (SLA) method, which uses a UV laser to cure a liquid resin that contains ceramic particles. However, this method also has drawbacks, such as low resolution, low strength, and high shrinkage.
Some ceramics, such as diamond, boron nitride, and silicon carbide, are almost impossible to 3D print using any of these methods, because they have extremely high hardness, thermal stability, and chemical resistance. These ceramics require very high temperatures and pressures to melt and fuse, which are beyond the capabilities of most 3D printers. Moreover, these ceramics are prone to cracking, warping, and degradation during the 3D printing process.
Polymers are the most common materials used in 3D printing, especially for consumer and hobbyist applications. Polymers have low cost, high flexibility, and high diversity, which make them suitable for many creative and functional applications. However, polymers also have some limitations that prevent them from being 3D printed easily or effectively. Some polymers, such as ABS, PLA, and nylon, can be 3D printed using methods such as fused deposition modeling (FDM), which extrudes a heated filament of plastic through a nozzle and deposits it layer by layer. However, these methods have drawbacks, such as low resolution, low strength, and high warping.
Other polymers, such as rubber, silicone, and foam, are more difficult to 3D print using these methods, because they have high elasticity and low rigidity, which means they do not hold their shape well. To overcome these challenges, some 3D printers use a polyjet method, which jets droplets of liquid polymer onto a platform and cures them with UV light. However, this method also has drawbacks, such as high cost, low durability, and high toxicity.
Some polymers, such as cellulose, starch, and chitin, are almost impossible to 3D print using any of these methods, because they have high biodegradability and low compatibility with synthetic polymers. These polymers require special processing and additives to make them suitable for 3D printing, which are not widely available or affordable. Moreover, these polymers are prone to decomposition, contamination, and infection during the 3D printing process.
Conclusion
3D printing is a powerful technology that can create objects from various materials, but it also has some limitations. Some materials cannot be 3D printed because they are too hard, too soft, too brittle, too toxic, or too complex. These materials include some metals, ceramics, and polymers, which have different challenges and drawbacks for 3D printing. Therefore, 3D printing is not a universal solution for all materials, and it requires careful selection and optimization of the materials and methods for each application.
