Many laypeople think3D printingIt involves extruding material from a hot nozzle and stacking it into shapes, but in reality3D printingIt’s much more than that! Today, Mohou.com will introduce seven major categories of 3D printing processes. Even a 3D printing novice can clearly distinguish between different 3D printing processes.
In fact, 3D printing, also known as additive manufacturing, is an umbrella term that covers several distinct 3D printing processes. The technologies are polar opposites, but the key processes are the same. For example, all 3D printing starts with a digital model because the technology is digital in nature. Parts or products are initially designed using computer-aided design (CAD) software or electronic files obtained from digital part libraries. The design file is then run through special build preparation software which breaks it down into slices or layers for 3D printing, thus producing3D printerDirections to follow. You will then learn the differences between these technologies and the typical uses of each.
Why 7 types?
Types of additive manufacturing can be divided based on the products they make or the types of materials they use,The International Organization for Standardization (ISO) divides it into seven general types(But these seven 3D printing categories also struggle to cover the growing number of technology subtypes and hybrid technologies). :
●Material extrusion
●Restore aggregation
●Powder bed fusion
●Material jet
●Binder jet
●Directed energy deposition
● Sheet lamination
1. Material extrusion
△3D printing by material extrusion
Material extrusion is exactly what it sounds like: material is extruded through a nozzle. Typically, the material is a plastic filament melted and extruded through a heated nozzle. The printer places the material on the build platform along a software-derived process path. The filament then cools and solidifies to form a solid object. This is the most common form of 3D printing. This may seem simple at first, but it’s actually a very broad category considering the materials extruded include plastics, metals, concrete, biogels, and various food products. Prices for this type of 3D printer range from $100 to seven figures.
●Material extrusion subtypes: Fused Deposition Modeling (FDM), Architectural 3D Printing, Micro-3D Printing, Bio-3D Printing
●Material: plastic, metal, food, concrete, etc.
●Dimensional accuracy: ±0.5% (lower limit ±0.5 mm)
●Common applications: prototypes, electrical enclosures, form and fit testing, jigs and fixtures, investment casting models, houses, etc.
●Advantages:The least expensive 3D printing method with a wide range of materials
●Disadvantages: Material properties are generally low (strength, durability, etc.) and dimensional accuracy is generally not high.
1. Fused Deposition Modeling (FDM)
△FDM parts can be made from metal or plastic on a variety of 3D printers
FDM 3D printers are a multi-billion dollar market with thousands of machines ranging from basic to sophisticated models from manufacturers. The FDM machine is called Fused Filament Fabrication (FFF), which is exactly the same technology. Like all 3D printing technologies, FDM starts with a digital model then converts it into3D printerpath to follow. With FDM, a spool of filament (or several at a time) is loaded into the 3D printer and fed through the printer nozzle into the extrusion head. The printer nozzle(s) are heated to the desired temperature, softening the filament so that successive layers come together to form a solid part.
As the printer moves the extrusion head along the specified coordinates in the XY plane, it continues to deposit the first layer. The extrusion head then rises to the next height (the Z plane) and the process of printing the cross section is repeated, building layer by layer until the object is fully formed. Depending on the geometry of the object, it is sometimes necessary to add support structures to support the model during printing, for example if the model has pronounced overhangs. These supports are removed after printing. Some support structure materials can be dissolved in water or another solution.
△FDM 3D printers offer a wide range of machines for hobbyists, small businesses and manufacturers (Source: Creality, Raise3D, Stratasys)
2.3D bioprinting
△3D bioprinting is similar to traditional 3D printing, but the raw materials are very different.
3D bioprinting, or 3D bioprinting, is an additive manufacturing process in which organic or biological materials, such as living cells and nutrients, are combined to create natural three-dimensional structures that resemble tissue. In other words, bioprinting is a type of 3D printing that can produce anything from bone tissue to blood vessels to living tissue. It is used in various medical research and applications, including tissue engineering, drug testing and development, and innovative regenerative medicine therapies. The very definition of 3D bioprinting is still evolving. Essentially, 3D bioprinting works similar to FDM 3D printing and belongs to the material extrusions family. (Although extrusion is not the only bioprinting method)
3D bioprinting uses material (bio-ink) expelled from a needle to create printed layers. These materials, called bioinks, are mainly composed of living substances, such as cells in a carrier material – such as collagen, gelatin, hyaluronic acid, silk, alginate or nanocellulose, molecules that act as structural growth support and nutrients to provide support.
3. Architectural 3D printing
△Architectural 3D printing
Architectural 3D printing is a rapidly growing field of material extrusion. The technology involves using very large 3D printers, often tens of meters high, to extrude construction materials such as concrete from nozzles. These machines generally come in the form of gantry systems or robotic arms. Architectural 3D printing technology is now used in homes, architectural features and construction projects, from wells to walls. Researchers say this has the potential to significantly change the entire construction industry, as it reduces labor requirements and construction waste.
There are dozens of 3D printed houses in the United States and Europe, and research is underway to develop 3D building technology that will use materials found on the Moon and Mars to create habitats for future expeditions. Printing with local soil instead of concrete is also gaining ground as a more sustainable construction method.
2. Reduction and polymerization
△Laser reduction polymerization
Barrel curing (also known as resin 3D printing) is a family of 3D printing processes that use a light source to selectively cure (or harden) a photopolymer resin in a barrel. In other words, light is aimed precisely at specific points or areas of the liquid plastic to harden it. After the first layer cures, the build platform moves slightly up or down (depending on the printer) (usually between 0.01 and 0.05 mm) and the next layer solidifies, joining the previous layer. This process is repeated layer by layer until a 3D part is formed. Once the 3D printing process is complete, the object is cleaned to remove remaining liquid resin and then cured (in the sun or in a UV chamber) to improve the mechanical properties of the part.
The three most common forms of barrel aggregation are stereolithography (SLA), digital light processing (DLP), and liquid crystal display (LCD), also known as mask stereolithography (MSLA). . The fundamental difference between these types of 3D printing technologies is the light source and how it is used to cure the resin.
△Vat curing uses light to cure photoresist layer by layer
Some 3D printer manufacturers, particularly those that make professional-grade 3D printers, have developed unique, patented light curing variants. So you can see different names for this technology in the market. Carbon, a manufacturer of industrial 3D printers, uses a barrel polymerization technology called digital light synthesis (DLS), Stratasys’ Origin calls its technology programmable photopolymerization (P3), and Formlabs offers what it calls stereolithography technology. low force (LFS). Azul 3D is the first to commercialize vat aggregation in the form of rapid large area printing (HARP). There is also photolithography-based metal fabrication (LMM), projected microstereolithography (PμSL), and digital composite manufacturing (DCM), a charged photopolymer technology that incorporates functional additives such as metal and ceramic fibers) introduced into liquid resin.
●Types of 3D printing technology: stereolithography (SLA), liquid crystal display (LCD), digital light processing (DLP), micro-stereolithography (μSLA), etc.
●Material: Photopolymer resin (castable, transparent, industrial, biocompatible, etc.)
●Dimensional accuracy: ±0.5% (lower limit is ±0.15 mm or 5 nm, using μSLA)
●Common applications: injection-molded polymer prototypes and end-use parts, jewelry casting, dental applications, consumer products
●Advantages: smooth surface finish, fine details
1. Stereolithography (SLA)
△Stereolithography (SLA) SLA 3D printing examples from 3D Systems, DWS and Formlabs
SLA is the first in the world3D printing technology. Stereolithography was invented in 1986 by Chuck Hull, who patented the technology and founded 3D Systems to commercialize it. Today, the technology is accessible to amateurs and professionals from many 3D printer manufacturers. SLA uses a laser beam aimed at a vat of resin to selectively harden cross-sections of the object in the print area, building it up layer by layer. Most SLA printers use a solid state laser to cure the part. One disadvantage of this barrel curing is that the point laser may take longer to trace the cross section of the object than our next method (DLP), which flashes the light to cure the entire layer at the same time . However, lasers can produce stronger light, which is necessary for some engineering-grade resins.
△SLA 3D printers use one or more lasers to track and cure a single layer of resin at a time.
Microstereolithography (μSLA)
Microstereolithography allows microscopic parts to be printed with resolutions between 2 micrometers (μm) and 50 μm. For reference, the average width of human hair is 75 microns. This is one of the “micro 3D printing” technologies. μSLA consists of exposing a photosensitive material (liquid resin) to a UV laser. The difference is the specialized resin, the complexity of the laser, and the addition of lenses that create almost impossibly small points of light.
△Nanoscribe and Microlight3D are two main manufacturers of TPP 3D printers (Source: Nanoscribe, Microlight3D)
Two-photon polymerization (TPP)
Another type of microphone3D printing technologyTPP (also known as 2PP) can be classified as SLA because it also uses a laser and photoresist, and it can print smaller parts than μSLA, as small as 0.1 microns. TPP uses a pulsed femtosecond laser focused on a narrow spot in a special resin vat. This point is then used to harden individual 3D pixels, also called voxels, in the resin. By sequentially solidifying these small voxels at the nanometer to micrometer scale layer by layer according to a predefined path. TPP is currently used in research, medical applications and the manufacturing of microscopic parts such as microelectrodes and optical sensors.
△Micro 3D printing: TPP technology
2. Digital Light Processing (DLP)
△DLP 3D printed parts from Anycubic, Carbon and ETEC
DLP 3D printing uses a digital light projector (rather than a laser) to simultaneously flash a single image of each layer (or multiple exposures for larger parts) onto a layer or resin. DLP (more common than SLA) is used to produce larger or higher volume parts in a single batch, because each exposure layer takes exactly the same amount of time, regardless of the number of parts in the build, than in SLA laser methods. are more effective. The image on each layer is made up of square pixels, which causes a layer to be formed from small rectangular blocks called voxels. Light is projected onto the resin using a light-emitting diode (LED) display or UV light source (lamp), and onto the build surface via a digital micromirror device (DMD).
△DLP (Digital Light Processing) resin 3D printers range from hobby versions to full production machines.
Modern DLP projectors typically have thousands of micron-sized LEDs as light sources. Their switching state is individually controlled, which can improve XY resolution. Not all DLP 3D printers are the same: the power of the light source, the lens it passes through, the quality of the DMD, and the many other parts that make up a $300 machine can all differ significantly from a printer that costs over $200,000 in comparison. has.
Downstream DLP
Some DLP 3D printers have a light source mounted on the top of the printer that illuminates the resin body rather than upwards. These “top-down” machines project an image from the top, cure it one layer at a time, then return the cured layer to the vat. Each time the build plate is lowered, a lap device mounted above the tank moves back and forth over the resin to level the new layer. The manufacturer claims that this method produces more stable part production for larger prints because the printing process is not fighting gravity. When printing from the bottom up, there is a limit to the weight that can be hung vertically from the build plate. The resin body also supports the print during printing, reducing the need for support structures.
△BMF’s MicroArch S230 can print detailed polymer or ceramic parts as small as 2 microns (Source: BMF)
Projection microstereolithography (PμSL)
As a distinct type of compartment aggregation, PμSL is classified as a subcategory of DLP. This is another 3D micro-printing technology. PμSL uses UV light from a projector to cure layers of specially formulated resin to the micron level (2 micron resolution and layer heights as low as 5 microns). This additive manufacturing technology continues to evolve due to its low cost, precision, speed, and the range of materials that can be used, including polymers, biomaterials, and ceramics. It has shown potential for applications ranging from microfluidics and tissue engineering to micro-optics and biomedical microdevices.
Lithography-Based Metal Fabrication (LMM)
Another distant cousin of DLP, this 3D printing method using light and resin creates tiny metal parts for applications such as surgical tools and micro-machined parts. In LMM, metal powder is uniformly dispersed in a photoresist and then exposed to blue light via a projector for selective polymerization. After printing, the polymer components of the green parts are removed, leaving all-metal, degreased parts that are completed in a sintering process in an oven. Raw materials include stainless steel, titanium, tungsten, brass, copper, silver and gold.
△3D micrometal printed parts produced on Incus 3D printing using LMM technology
3. Liquid crystal display (LCD)
△LCD 3D printed parts from Elegoo, Photocentric and Nexa3D.
Liquid crystal display (LCD), also known as mask stereolithography (MSLA), is very similar to the DLP above, except that it uses an LCD instead of a digital micromirror device ( DMD), which has a significant impact on the price of the 3D printer has an impact. Like DLP, LCD photomasks are digital screens made up of square pixels. The pixel size of the LCD photomask determines the granularity of the print. Therefore, the XY precision is fixed and does not depend on the zoom or zoom level of the lens, as is the case with DLP. Another difference between DLP printers and LCD technology is that the latter uses an array of hundreds of individual emitters rather than a single point emitting light source like a laser diode or DLP bulb.
△Today, LCD resin 3D printing technology is moving from consumer machines to industrial machines
Like DLP, LCD can achieve faster print times than SLA under certain conditions. This is because the entire layer is exposed at once, rather than tracing the cross-sectional area with a laser point. Due to the low cost of LCD units, this technology has become the technology of choice in the field of low-cost desktop resin printers, but that does not mean that it is not used professionally, and some manufacturers of industrial 3D printers are pushing the limits. technology and achieve impressive results.
3. Powder bed fusion
△Powder bed fusion
Powder bed fusion (PBF) is a 3D printing process in which thermal energy selectively melts powder particles (plastic, metal, or ceramic) in the build area to create a solid object layer by layer. Powder bed fusion 3D printers spread a thin layer of powdered material onto the print bed, usually using a blade, roller, or wiper. The laser energy fuses specific points on the powder layer, then another powder layer is deposited and merged with the previous layer. The process is repeated until the entire object is made, with the final product wrapped and supported by unmelted powder.
△Metal laser powder bed fusion process
PBF enables the manufacturing of parts with high mechanical properties, including strength, wear resistance and durability, for end-use applications in consumer products, machinery and tools. 3D printers in this segment are getting cheaper (starting from around $25,000), but they are considered industrial technology.
●Types of 3D printing technologies: selective laser sintering (SLS), laser powder bed fusion (LPBF), electron beam fusion (EBM)
●Material: plastic powder, metal powder, ceramic powder
●Dimensional accuracy: ±0.3% (lower limit ±0.3 mm)
●Common applications: functional components, complex pipes (hollow design), small batch component production
●Advantages: functional components, excellent mechanical properties, complex geometries
●Disadvantages: higher machine costs, often expensive materials, slower build speeds
1. Selective laser sintering (SLS)
△SLS 3D printed parts from Sinterit
Selective laser sintering (SLS) uses a laser to create objects from plastic powder. First, a can of polymer powder is heated to a temperature just below the melting point of the polymer. A very thin layer of powdered material (typically 0.1mm thick) is then deposited onto the build platform using a cover blade or wiper. The laser begins scanning the surface according to the pattern drawn in the digital model. The laser selectively sinters the powder and solidifies the cross sections of the object. As the entire cross section is scanned, the build platform moves down one thickness in height. The cover blade deposits a new layer of powder on top of the most recently scanned layer, and the laser sinters the next cross-section of the object onto the previously solidified cross-section.
△SLS 3D printed parts can be removed and cleaned manually or automatically
Repeat these steps until all objects are created. The unsintered powder remains in place to support the object, reducing or eliminating the need for support structures. Once parts are removed from the powder bed and cleaned, no further post-processing steps are required. Parts can be polished, coated or stained. There are many differentiating factors between SLS 3D printers, including their size, but also the power and number of lasers, the spot size of the lasers, when and how the bed is heated, and how the powder is heated. is distributed. The most commonly used materials in SLS 3D printing are nylon (PA6, PA12), but flexible parts can also be printed using TPU and other materials.
△SLS 3D printer uses polymer powder and laser to form solid parts
2. Micro-selective laser sintering (μSLS)
μSLS belongs to the SLS or Laser Powder Bed Fusion (LPBF) technology described below. It uses a laser to sinter a powdered material, like SLS, but that material is usually metal rather than plastic, so it’s more like LPBF. This is another micro-3D printing technology that allows parts to be created at microscopic resolution (less than 5 μm).
△Metal 3D micro-printing from 3D MicroPrint
In μSLS, a layer of metal nanoparticle ink is applied to a substrate and then dried to produce a uniform layer of nanoparticles. Next, a laser patterned using a digital micromirror array is used to heat the nanoparticles and sinter them into the desired pattern. This set of steps is then repeated to build each layer of the 3D part in the μSLS system.
3. Laser powder bed fusion (LPBF)
△Xact Metal test sample showing SLM accuracy (Source: Xact Metal)
Of all 3D printing technologies, this one has the most aliases. This metal 3D printing method, formerly known as laser powder bed fusion (LPBF), is also widely known as direct metal laser sintering (DMLS) and selective laser melting (SLM). Early in the development of this technology, machine builders created their own names for the same processes, and these names are still used today. In particular, these three terms refer to the same process, even if certain mechanical details differ.
A subtype of powder bed fusion, LPBF uses a metal powder bed and one or more (up to 12) high-power lasers. LPBF 3D printers use lasers to selectively fuse metal powders layer by layer on a molecular basis until the pattern is complete. LPBF is a high-precision 3D printing method commonly used to create complex metal parts for aerospace, medical and industrial applications.
△LPBF metal 3D printing from Sandvik
Like SLS, LPBF 3D printers start with a digital model divided into slices. The printer loads the powder into the build chamber, then spreads it in a thin layer on the build plate using a scraper (like a windshield wiper) or roller. The laser traces the layers on the powder. The build platform then lowers and another layer of powder is applied and mixed with the first layer until the entire object is built. The manufacturing chamber is closed, sealed, and in many cases filled with an inert gas, such as a mixture of nitrogen or argon, to ensure that the metal does not oxidize during the melting process and to help remove debris from the melting process. After printing, parts are removed from the powder bed, cleaned, and often subjected to a secondary heat treatment to reduce stress. The remaining powder is recycled and reused.
Differentiating factors for LPBF 3D printers include the type, intensity and number of lasers. A small, compact LPBF printer might have one 30-watt laser, while an industrial version might have 12 1,000-watt lasers. LPBF machines use common engineering alloys such as stainless steel, nickel superalloys and titanium alloys. There are dozens of metals available for the LPBF process.
△LPBF 3D printers from One Click Metal, Farsoon and Kurtz Ersa.
3. Electron beam fusion (EBM)
△Electron beam fusion (EBM)
EBM, also known as electron beam powder bed fusion (EB PBF), is a metal 3D printing method similar to LPBF, but uses an electron beam instead of a laser fiber. This technology is used to make parts such as titanium orthopedic implants, jet engine turbine blades and copper coils.
Electron beams produce more energy and heat, needed for certain metals and applications. Furthermore, EBM is not carried out in an inert gas environment but in a vacuum chamber to avoid beam scattering. Temperatures in the manufacturing chamber can reach 1000°C, or even higher in some cases. Because the electron beam is directed using an electromagnetic beam, it can travel faster than a laser and can even be split to expose multiple areas simultaneously.
△Electron beam fusion (EBM) metal 3D printers from JEOL, GE Additive and Wayland Additive.
One of the advantages of EBM over LPBF is its ability to handle conductive materials and reflective metals, such as copper. Another feature of EBM is the ability to nest or stack individual parts on top of each other in the build chamber, as they do not necessarily have to be connected to the build plate, which significantly increases the volumetric flow. Compared to lasers, electron beams generally produce thicker layers and rougher surfaces. Due to high temperatures in the build chamber, EBM printed parts may not require post-printing heat treatment to relieve stress.
4. Material injection
△Material injection
Material jetting is a 3D printing process in which tiny droplets of material are deposited and then solidified, or solidified, onto the build plate. The objects are built layer by layer using droplets of photopolymer or wax that solidify when exposed to light. The nature of the material projection process allows different materials to be printed on the same object. One application of this technology is creating pieces in a variety of colors and textures.
●Types of 3D printing technology: material jetting (MJ), nanoparticle jetting (NPJ)
●Material: Photosensitive resin (standard, cast, transparent, high temperature resistant), wax
●Dimensional accuracy: ±0.1 mm
●Common applications: color product prototypes, injection mold prototypes, small series injection molds, medical models, fashion
●Benefits: textured surface finish, color and multiple materials available
●Disadvantages: limited materials, not suitable for mechanical parts requiring precision, higher cost than other resin technologies used for visual purposes
1. Material jet (M-Jet)
△Stratasys material projection 3D printed parts
Polymer material jetting (M-Jet) is a 3D printing process in which a layer of photosensitive resin is selectively deposited on a build plate and cured with ultraviolet (UV) light. Once a layer is deposited and solidified, the build platform reduces the thickness of the layer and the process is repeated to build the 3D object. M-Jet combines the high precision of resin 3D printing with the speed of filament 3D printing (FDM) to create parts and prototypes with realistic colors and textures.
Not all material jet 3D printing technologies are the same. There are differences between printer manufacturers and proprietary materials. The M-Jet machine deposits build material from multiple rows of printheads, line by line. This approach allows the printer to manufacture multiple objects on a single line without affecting manufacturing speed. As long as the model is properly laid out on the build platform and the space within each build line is optimized, the M-Jet can produce parts faster than many other types of resin 3D printers .
△Material jet 3D printers from Stratasys, DP Polar/3D Systems and Mimaki
Objects made with M-Jet require supports that are simultaneously printed during the build process from a soluble material that is removed during a post-processing step. M-Jet is one of the few 3D printing technologies to offer objects made from multi-material and full-color printing. There is no hobbyist version of material jetting machines, these machines are more suited to professionals in automobile manufacturers, industrial design companies, art studios, hospitals and all types of product manufacturers who want to create accurate prototypes to test concepts and bring products to market more quickly. Unlike barrel cure technology, M-Jet requires no post-curing because the UV light from the printer completely cures each layer.
aerosol spray
Aerosol Jet is a unique technology developed by a company called Optomec, primarily used for 3D printing electronics. Components such as resistors, capacitors, antennas, sensors and thin film transistors are printed using aerosol jet technology. It can be roughly compared to spray paint, but what differentiates it from industrial coating processes is that it can be used to print complete 3D objects.
The electronic ink is placed in an atomizer which produces droplets with a diameter of between 1 and 5 microns. The aerosol mist is then transported to the deposition head and focused by the sheath gas, producing high-velocity particle spray. Due to the energy used throughout the process, this technique is sometimes called directed energy deposition, but because the material in this case is in droplet form, we include it in the material ejection.
plastic free forming
German company Arburg created a technology called plastic free forming (APF), which is a combination of extrusion and material injection. It uses commercially available plastic pellets that are melted during the injection molding process and moved to an unloading unit. Closing the high-frequency nozzle produces a rapid opening and closing movement of up to 200 plastic droplets per second with a diameter between 0.2 and 0.4 mm. The droplets combine with the hardened material as it cools. Generally no post-processing is required. If support material is used, it must be removed.
2. Nanoparticle jet (NPJ)
△Metal parts created using nanoparticle jet technology and the XJet 3D printer
NanoParticle Jetting (NPJ) is one of the few proprietary technologies that is difficult to classify. Developed by a company called XJet, it uses an array of print heads with thousands of inkjet nozzles to simultaneously print millions of ejected ultra-fine droplets of material. an ultra-thin layer of construction pallets, simultaneously ejecting the support material. Metal or ceramic particles are suspended in a liquid. The process occurs at high temperatures and the liquid evaporates as it sprays, leaving virtually nothing but the metal or ceramic. The resulting 3D part retains only a small amount of binder, which is removed during the post-sintering process.
5. Spraying adhesive
△Binder jet
Binder jetting is a 3D printing process in which a liquid adhesive selectively bonds areas of a powder layer. This type of technology combines the characteristics of powder bed fusion and material ejection. Like PBF, binder jetting uses powdered materials (metals, plastics, ceramics, wood, sugar, etc.) and, like material jetting, a liquid binder polymer is deposited from an inkjet . Whether metal, plastic, sand or other powder materials, the binder jetting process is the same.
First, cover the blade by applying a thin layer of powder to the build platform. A print head with an inkjet nozzle then passes over the bed, selectively depositing droplets of adhesive to bind the powder particles together. Once the layer is complete, the build platform descends and the blade covers the surface. Then repeat the process until the entire section is complete.
Binder jetting is unique in that there is no heat during the printing process. The binder acts like the glue that holds the polymer powder together. After printing, the parts are encased in unused powder, which is usually left to harden. The part is then removed from the powder bin, the excess powder is collected and can be reused. From there, post-processing is required depending on the material, with the exception of sand, which can often be used as a core or mold straight from the printer. When the powder is metallic or ceramic, post-processing involving heat melts the binder, leaving only the metal. Post-processing of plastic parts often includes coatings to improve the surface finish. You can also polish, paint and sand the sprayed parts with polymer glue.
Binder jetting is fast and productive, allowing large volumes of parts to be produced more cost-effectively than other additive manufacturing methods. Metal binder spray can be used on a variety of metals and is popular in end consumer goods, tools and bulk replacement parts. However, polymer binder jetting offers limited material options and produces parts with inferior structural properties. Its value lies in the ability to produce full-color prototypes and models.
●3D printing technology subtypes: metal binder jetting, polymer binder jetting, sand binder jetting
●Material: sand, polymer, metal, ceramic, etc.
●Dimensional accuracy: ±0.2 mm (metal) or ±0.3 mm (sand)
●Common applications: functional metal parts, color models, sand castings and molds
●Benefits: low cost, high manufacturing volume, functional metal parts, excellent color reproduction, fast print speeds, supportless design flexibility
●Disadvantages: A multi-step process for metal and polymer parts is not sustainable
1. Spray metal adhesive
△HP uses Metal Jet technology to 3D print stainless steel parts
Binder jetting can also be used to create solid metal objects with complex geometries that are far beyond the capabilities of traditional manufacturing techniques. Metal binder jetting is a very interesting technology for the mass production and lightweighting of metal parts. Since binder jetting can print parts with complex infill patterns instead of solid bodies, the resulting parts are significantly lighter but remain just as strong. The porosity characteristics of the adhesive spray can also be used to achieve lighter end pieces for medical applications, such as implants.
Overall, the material properties of metal binder jet molded parts are comparable to those produced by metal injection molding and are one of the most widely used manufacturing methods for mass production of metal parts. Additionally, the sprayed adhesive parts have a smoother surface, especially in the internal channels.
△Metal Binder Jet 3D Printer produces finely detailed solid metal parts for end applications
Parts sprayed with a metal binder require secondary processing after printing to obtain good mechanical properties. Fresh off the printer, the part is essentially made of metal particles held together with a polymer adhesive. These so-called “green” parts are fragile and cannot be used as is. After the printed parts are removed from the bed of metal powder (a process called depowdering), they are heat treated in an oven (a process called sintering). Printing and sintering parameters are tailored to the specific part geometry, material and desired density. Bronze or other metals are sometimes used to penetrate the voids of sandblasted parts with glue, thereby achieving zero porosity.
2. Spraying plastic glue
△Spraying plastic adhesive
Plastic binder jetting is a very similar process to metal binder jetting in that it also uses powder and liquid binders, but the application is quite different. Once printed, plastic parts are removed from their powder bed, cleaned, and generally ready for use without additional processing, but these parts lack the strength and durability of the 3D printing process. Parts sprayed with a plastic binder can be filled with another material for greater strength. Binder jetting using polymers is known for its ability to produce multi-colored parts for medical modeling and product prototyping.
3. Spraying sand binder
△Sand binder spraying
Sand binder jetting has different printers and printing processes than plastic binder jetting, so they will be distinguished here. The production of large sand casting molds, patterns and cores is one of the most common uses of binder jetting technology. The low cost and speed of the process make it an excellent solution for foundries, as it is difficult to produce fine designs in a few hours using traditional techniques.
The future of industrial development continues to place high demands on foundries and suppliers. 3D sand printing is at the beginning of its potential. After printing, the printer will need to remove the core and mold from the build area and clean them to remove any loose sand. The mold is usually ready to pour immediately. After casting, the mold is dismantled and the last metal parts are removed.
4. Multi-jet fusion (MJF)
△BASF and HP collaborated to develop new industrial-grade polypropylene for MJF
HP’s Multi Jet Fusion is another unique, brand-specific 3D printing process that doesn’t fit into any existing categories and isn’t actually binder jet. MJF is a polymer 3D printing technology that uses powder materials, liquid fusion materials and refiners. The reason it is not considered adhesive spray is that heat is added to the process, resulting in a stronger, more durable part, and liquid is not exactly an adhesive. The process gets its name from the multiple inkjet heads that carry out the printing process.
During the Multi Jet Fusion printing process, the printer deposits a powder layer of material, usually nylon, onto the print bed. Then the inkjet head passes through the powder and deposits fusing and refining agents. The infrared heater then moves over the print. Wherever flux is added, the underlying layers melt together while the areas with the refiner remain powdery. The powdery parts fall, creating the desired geometry. This also eliminates the need for modeling support, as the underlying layers support the printed layers above them. To complete the printing process, the entire powder bed and the printed parts it contains are moved to a separate processing station, where most of the unmelted loose powder is removed and can be reused.
Multi Jet Fusion is a versatile technology that has found applications in many industries, including automotive, healthcare and consumer products.
△The HP Jet Fusion 5200 series is one of several sizes and styles of HP Multi Jet Fusion 3D printers (Source: HP)
6. Directional powder energy deposition
Directed energy deposition (DED) is a 3D printing process in which metallic materials are supplied and melted by powerful energy during their deposition. This is one of the broadest categories of 3D printing, with many subcategories depending on the shape of the material (wire or powder) and the type of energy (laser, electron beam, arc, supersonic, thermal, etc.). Essentially, it has a lot in common with welding.
This technology is used to print layer by layer, often followed by CNC machining to achieve tighter tolerances. Using DED in conjunction with CNC is very common, and there is a subtype of 3D printing called hybrid 3D printing, a hybrid 3D printer that contains both DED and CNC units in the same machine. This technology is considered a faster, lower cost alternative to low volume metal castings and forgings, as well as critical repairs for applications in the offshore oil and gas industry as well as in the aerospace sectors, electricity production and public services.
△DED metal 3D printing technology can quickly create a solid metal part that can then be machined to tight tolerances.
●Subtypes of directed energy deposition: powder laser energy deposition, wire arc additive manufacturing (WAAM), wire electron beam energy deposition, cold spray
●Materials: various metals, shapes of wires and powders
●Dimensional accuracy: ±0.1 mm
●Common applications: repair of high-end automotive/aerospace components, functional prototypes and final parts
●Advantages: high stacking rate, possibility of adding metal to existing components
●Disadvantages: Inability to create complex shapes due to inability to create support structures, usually poor surface finish and accuracy
1. Laser-directed energy deposition
△3D metal printing using laser and metal powder
Laser-directed energy deposition (L-DED), also known as laser metal deposition (LMD) or laser array shaping (LENS), uses metal powder or wire sent through one or more nozzles and melted by powerful laser to build the platform or onto metal parts. Objects are deposited layer by layer as the nozzle and laser move or as the part moves on a multi-axis turntable. The manufacturing speed is faster than powder bed fusion, but results in lower surface quality and significantly lower precision, often requiring extensive post-processing. DED laser printers typically have a sealed chamber filled with argon to prevent oxidation. They can also operate using only localized argon or nitrogen when working with less reactive metals.
Common metals used in this process include stainless steel, titanium and nickel alloys. This printing method is commonly used to repair high-end aerospace and automotive parts, such as jet engine blades, but it is also used to produce entire components.
△Meltio M450 wire laser DED 3D printer, Optomec LENS CS 600 metal powder laser DED 3D printer and DMG Mori Lasertec 65 DED powder laser DED 3D printer.
2. Directional energy deposition by electron beam
△3D DED printing by electron beam
Electron beam DED, also known as linear electron beam energy deposition, is a 3D printing process very similar to laser DED. This is done in a vacuum chamber and produces very clean, high quality metal. When a wire passes through one or more nozzles, it is melted by the electron beam. The layers are built individually, with a beam of electrons forming a tiny molten pool into which welding wire is fed through a wire feeder. Electron beams are chosen for DED when processing high-performance metals and reactive metals such as copper, titanium, cobalt and nickel alloys.
DED machines are virtually unlimited in print size. For example, 3D printer manufacturer Sciaky has an EB DED machine capable of producing parts nearly 6 meters long at a rate of 3 to 9 kilograms of material per hour. Electron beam DED is touted as one of the fastest methods of manufacturing metal parts, although it is not the most precise, making it an ideal machining technology for building large structures such as fuselages or spare parts such as turbine blades.
△3D printing by electron beam deposition
3. Wire controlled energy deposition
△Gefertec Electric Arc Additive Manufacturing (WAAM) printing
Wire-directed energy deposition, also known as wire-arc additive manufacturing (WAAM), is a type of 3D printing that uses energy in the form of plasma or arc to melt metal in wire form and deposit the metal layer by layer via a robotic arm. A surface, such as a multi-axis turntable, forms a shape. This method was chosen over similar technologies such as laser or electron beam because it does not require a sealed chamber and can use the same metals (sometimes the exact same materials) as traditional welding.
Direct electrical energy deposition is considered the most cost-effective option among DED technologies and can utilize existing arc welding robots and power sources, so the barrier to entry is relatively weak. But unlike welding, this technology uses sophisticated software to control a series of variables in the process, including thermal management of the robotic arm and tool paths. There is no support structure to remove with this technology, and the finished part is typically CNC machined to tight tolerances or surface polished if necessary.
△Wired arc additive manufacturing 3D printer from Gefertec and WAAM3D.
4. Cold spray
△Cold spray
Cold spray is a DED 3D printing technology that sprays metal powders at supersonic speeds to bond them without melting and creating virtually no thermal cracking or thermal stress. It has been used as a coating process since the early 2000s, but more recently several companies have adopted cold spray for additive manufacturing because it can print 50 to 100 times faster than traditional metal 3D processes, and this , without inert gas or vacuum chamber. required.
As with all DED processes, cold spray does not produce prints with high surface quality or detail, but parts can be used directly from the print bed.
5. Direct molten energy deposition
△Direct fusion energy deposition: aluminum parts produced using Xerox ElemX liquid metal 3D printing
Fused direct energy deposition is a 3D printing process that uses heat to melt a metal (usually aluminum) and then deposits it layer by layer onto a build plate to form a 3D object. This technology differs from metal extrusion 3D printing in that extrusion uses a raw metal material with a small amount of polymer inside, making the metal extrudable. The polymer is then removed in a heat treatment step, while the molten DED is filled with pure metal. Melted or liquid DED can also be compared to a jet of material, but instead of a series of nozzles depositing droplets, liquid metal typically flows from the nozzles.
Variations of this technology are being developed and molten metal 3D printers are rare. The advantage of using heat to melt and then deposit metal is the ability to use less energy than other DED processes and potentially use recycled metal directly as a raw material rather than wire or metal powder highly processed.
7. Sheet Lamination
△Sheet lamination
Technically, sheet lamination is a form of 3D printing and is very different from the techniques mentioned above. Its function is to stack and laminate very thin sheets of material to create a 3D object or stack, which is then cut mechanically or by laser to form the final shape. Layers of materials can be fused together using a variety of methods, including heat and sound, depending on the material, which ranges from paper to polymers to metals. When parts are laminated and then laser cut or machined into the desired shape, more waste is generated than with other 3D printing technologies.
Manufacturers use sheet lamination to produce cost-effective, non-functional prototypes at relatively high speeds for battery technology and to produce composite materials because the materials used can be interchanged during the printing process.
●Types of 3D printing technology: laminated object manufacturing (LOM), ultrasonic consolidation (UC)
●Material: paper, polymer and sheet metal
●Dimensional accuracy: ±0.1 mm
●Common applications: non-functional prototypes, multi-color printing, casting molds.
●Advantages: rapid production and composite printing
●Disadvantages: low precision, lots of waste, some parts require post-production
Laminated additive manufacturing
△Laminated additive manufacturing
Lamination is a 3D printing technique in which sheets of material are layered and held together using glue, then a knife (or laser or CNC router) is used to cut the layered object into the shape correct. This technology is less common today as the cost of other 3D printing technologies has fallen and the speed and ease of use have increased significantly.
△BCN3D uses a resin-based viscous lithography (VLM) 3D printing process (Source: BCN3D)
Viscolithography manufacturing (VLM):VLM is BCN3D’s patented 3D printing process that laminates a thin layer of high viscosity photosensitive resin onto a transparent transfer film. A mechanical system laminates the resin on both sides of the film, allowing different resins to be combined to obtain multi-material parts and easily removable support structures. This technology is not yet commercialized, but could also be part of 3D printing technologies by lamination.
Composite-based additive manufacturing (CBAM):Startup Impossible Objects has patented technology that fuses carbon, glass or Kevlar pads with thermoplastic to create parts.
Selective manufacturing of laminated composites (SLCOM):EnvisionTEC, now known as ETEC and owned by Desktop Metal, developed the technology in 2016, which uses thermoplastics as a base material and woven fiber composites.
Note: There are many types of 3D printing technologies. The seven most common types of additive manufacturing technologies in 3D printing above do not cover all 3D printing technologies available on the market.
Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.
