Antarctic Bear Guide:This issue will briefly summarize some mainstream 3D printing processes and focus on introducing some non-mainstream 3D printing technologies.Additive Manufacturing (AM) refers to the process of manufacturing parts or objects based on three-dimensional model data through material accumulation. 3D printing refers to the process of manufacturing parts or objects through material accumulation using a print head, nozzle, or other printing technologies; this term is often used synonymously with additive manufacturing, hence also referred to as “3D printing.”
△ 3D printed nozzle made of titanium
The manufacturing form is generally constructed in a layer-by-layer deposition manner. At the same time, internationally recognized ISO/ASTM has seven different types of additive manufacturing technologies: 1. Photopolymerization – UV light selectively cures liquid resin through point-by-point or layer-by-layer illumination;2. Powder Bed Fusion (PBF) – uses an energy source (usually a laser or electron beam) to fuse powdered metal or polymer together;3. Binder Jetting – a binder deposited on metal powder or sand forms a geometric shape; for metals, sintering is usually required after printing to melt the powder;4. Material Jetting – droplets of material are precisely deposited to create a geometry;5. Sheet Lamination – materials are stacked and laminated together by ultrasonic welding, brazing, adhesives, or chemical means;6. Material Extrusion – materials such as polymer filaments or pellets are heated and extruded through a nozzle;7. Directed Energy Deposition (DED) – metal powder or wire is fed into a melt pool generated by a laser or electron beam, a process similar to welding.Additionally, “Hybrid Manufacturing” describes a process that combines additive manufacturing with traditional subtractive techniques. For example, a CNC machine can be equipped with a DED print head, allowing the same machine to 3D print materials and perform milling.At the same time, it should be emphasized that each of these seven categories has different subcategories of 3D printing. For example, Directed Energy Deposition (DED) can use powder or wire to manufacture metal parts. Photopolymerization includes categories like Stereolithography (SLA) and Digital Light Processing (DLP), where SLA is point scanning, and DLP cures a layer at once.Machine manufacturers may also have proprietary processes or use different terminologies, in addition to these seven types of 3D printing processes, some special technical types.
△ Digital Light Synthesis (DLS) is a resin-based 3D printing process
1. Digital Light Synthesis (DLS)Digital Light Synthesis (DLS) is a proprietary resin-based 3D printing process developed by Carbon.How does DLS work?DLS is based on stereolithography. Both processes use UV light to cure resin. However, unlike stereolithography, Carbon’s process does not pause after each layer. The resin continuously flows over a “dead zone” above an oxygen-permeable membrane, where a UV image of the part’s cross-section is projected onto the oxygen-permeable window to cure the resin. When the build platform rises from the resin vat, the part is inverted.What materials can be used?Carbon offers DLS resins including elastomers, flexible, rigid, and medical-grade polyurethanes, silicones, cyanate esters, epoxies, polyurethane methacrylates, and dental materials.
△ Carbon’s Digital Light Synthesis 3D printing process
What post-processing is required?After printing, parts are removed from the build plate, and all supports are removed. Some materials also require thermal curing in an oven, which may take 4 to 13 hours to complete. Heat triggers secondary chemical reactions, enhancing the strength of the parts, and no further post-processing is needed after cleaning and curing.Why use DLS?The continuity of Carbon’s DLS 3D printing process avoids layer lines in parts, providing a surface finish comparable to injection-molded parts. DLS parts are also said to be waterproof and isotropic, having the same strength in all directions. Besides providing a method for prototyping, it can also serve as an alternative for manufacturing production parts.2. NanoParticle Jetting (NPJ)NanoParticle Jetting (NPJ) is a 3D printing process developed by XJet. This is a material jetting technology that uses a suspension of powdered material to build parts.How does NPJ work?NPJ jets a liquid containing suspended metal or ceramic material nanoparticles to build parts while simultaneously jetting a support material. The forming process occurs in a heated bed at 250°C, causing the liquid to evaporate during jetting, allowing the particles to adhere in all directions, with only a small amount of binder in the printed 3D object and support.What materials can be used?XJet supports the use of 316L stainless steel and two ceramic materials (zirconia and alumina) for NanoParticle Jetting. Materials are installed in the machine via cartridges, requiring no machining or processing.
△ Ceramic parts manufactured using NanoParticle Jetting technology
What post-processing is required?After printing, NPJ parts still retain a small amount of binder and may have support structures. The carrier material is water-soluble and can be dissolved in a water bath. If needed, machining or polishing can be done at this stage.
△ An example of a part manufactured through NPJ, with its soluble support material still intact
Why use NanoParticle Jetting?This process can produce many small parts at once. According to XJet, the material jetting process can be controlled drop by drop, achieving a range of ±25 microns for small parts and ±50 microns for larger MIM/CIM parts. The minimum feature size is 100 microns, and the layer height can be 8 to 10 microns, allowing for fine details.Since NPJ uses suspended materials, there is no need for sieving and other steps required for powdered processes. Materials can be printed in normal atmosphere without the need for special gases, vacuum, or pressure, and are easy to recycle.Applications of NanoParticle Jetting include hearing aids in the medical industry, surgical tools, dental crowns, dental bridges, and guide drills; high-temperature and wear-resistant parts for aerospace and automotive; and sensors for the electrical industry.3. Ultrasonic Additive Manufacturing (UAM)This process is developed by Fabrisonic, which manufactures metal parts by fusing and stacking metal strips. This work is done on a hybrid machine tool that can CNC mill the workpiece as additive manufacturing progresses. By stacking metal strips, rapid build speeds can be achieved, making large parts practical.
How does UAM work? In UAM, materials are not melted but are joined through ultrasonic welding. This welding uses high-frequency vibrations to connect surfaces while the metal remains solid. By welding layer by layer in this manner, robust parts are built.
△ This solid-state additive process enables parts to be produced using different metals
Under high-frequency ultrasonic vibrations and constant pressure, ultrasonic motion breaks down oxides through friction, allowing direct contact between metals.
△ This process forms solid atomic bonds or welds between thin metal strips and substrates with minimal heating, welding multiple layers together to increase height
Repeat this process until a solid part is built. CNC contour milling can then be used to achieve the desired tolerances and optimal surface finish of the part.Why use Ultrasonic Additive Manufacturing?Hard metal outer surfaces can be built on structures made of lighter metals to provide durability and lightweight parts. Alternatively, two distinctly different metals – such as titanium and aluminum can be combined into hybrid layers, forming a structure that combines the properties of both.This technology combines the practicality of additive manufacturing and subtractive manufacturing, allowing for the production of parts with complex geometries and internal channels. The fine dimensional accuracy and smooth surfaces of parts made using UAM and machining demonstrate the potential of hybrid manufacturing.4. Selective Thermoplastic Electronic Photographic Process (STEP)Developed by Evolve Additive Solutions, the Selective Thermoplastic Electronic Photographic Process (STEP) technology combines 2D imaging with proprietary IP to precisely align incoming layers and bond them into fully dense final parts, which are said to have isotropic properties equal to or exceeding injection molding.
△ STEP is designed for high-speed, large-scale additive manufacturing and factory workshop integration
What materials can be used?The company states that STEP’s candidate materials are the same as those available for injection molding polymers. However, materials provided as carbon powder require Evolve’s proprietary material engineering technology.STEP machines have multiple print heads, allowing for multiple colors in parts, but another possibility is the potential for multiple materials. Various different polymers applied at the voxel level can achieve performance combinations that cannot be obtained in any single material.Why use STEP?STEP offers a method to obtain thousands of plastic parts in days, while waiting for mold processing can take weeks. Moreover, because there are no molds, the unit cost at this quantity level is lower than molding. This process can produce parts without layer lines, and STEP matches heated layers with heated components, resulting in a more complete fusion than processes like FDM.5. Multi Jet Fusion (MJF)This process is a powder bed 3D printing process developed by HP, which binds reagents and powder together in a manner similar to binder jetting. Unlike powder bed fusion systems based on point-to-point lasers, MJF selectively distributes a fusion agent and detailing agent across the powder bed and uses infrared light to fuse layers together.
△ These sample parts made through Multi Jet Fusion illustrate the design freedom of the process and the potential variety of parts that can be formed in a single build. Since the printing process does not require support structures, parts can be nested and stacked to fill the entire build volume
The Multi Jet Fusion system consists of replaceable build units that can move between MJF 3D printers and separate post-processing stations for rapid cooling and powder removal. This modular system allows printers and post-processing stations to run continuously while build units cycle through, speeding up part production.
△ The Periscope housing was manufactured on HP’s Multi Jet Fusion 3D printing platform
What post-processing is required?After the build is complete, the build unit (the entire powder bed with encapsulated parts) is removed from the printer and placed in the post-processing unit for rapid cooling. The build unit is then moved to the processing station, where loose powder is removed via vacuum.Compared to laser-based powder bed processes like Selective Laser Sintering (SLS), the final parts are said to have high-quality surface finishes, fine feature resolution, and more consistent mechanical properties. Moreover, because heating is done layer by layer, with powder filling below the parts, the warping rate of MJF is lower than that of SLS.To improve surface finish, parts can be sandblasted and then primed or painted. If applications require, printed parts can be dyed or further processed.What materials can be used?Multi Jet Fusion is compatible with a range of thermoplastic materials from HP, including High Reusability (HR) PA 12 nylon, HR PA 12 GB (glass bead reinforced nylon), and HR PA 11.HP also supports a 3D materials certification program and collaborates with polymer 3D printing material suppliers to develop new materials. Material partners include Arkema, BASF, Dresler Group, Evonik, Henkel, Lehmann & Voss & Co., Lubrizol, and Sigma Design.Why use Multi Jet Fusion?This process can rapidly produce functional prototypes and end-use production parts within a day. If the build unit is swapped out for post-processing at the end of each print, a single MJF printer can run almost continuously. Used powder can be recycled.The layer-by-layer fusion of MJF is faster than point-by-point 3D printing systems and is said to require the same time to fuse each layer, regardless of complexity. MJF allows parts to be nested vertically and horizontally, filling the entire build volume with individual separate parts. Multi Jet Fusion does not require mold investment or minimum order quantities; these factors, combined with its speed, make this process competitive with injection molding in mass production.
For more details, see “Antarctic Bear Review: These 20 3D Printing Technologies Are Expensive, and China Is Almost Blank”
△ Event Theme: Tsinghua Kunshan Alumni Forum Third Session – Discussion on 3D Printing Technology
Event Time: July 23, 14:00-16:00
Participation Method: Tencent Meeting Online
This issue will invite Professor Yan Yongnian, a professor and doctoral supervisor at Tsinghua University, chairman of Yongnian Laser, and recognized as “China’s No. 1 in 3D Printing,” along with Pan Xuesong, co-founder of Antarctic Bear 3D Printing Network, to give online reports and share insights. Welcome to sign up for participation.