Many laypeople think that 3D printing is just extracting material from a hot nozzle and stacking it into shapes, but 3D printing goes far beyond that! Today, we introduce seven types of 3D printing processes to help differentiate the various 3D printing techniques.
In fact, 3D printing, also known as additive manufacturing, is a general term that encompasses several distinct 3D printing processes. These technologies vary greatly, but the core processes are the same.
For example, all 3D printing starts with a digital model because the technology is essentially digital. The part or product is initially designed using computer-aided design (CAD) software or sourced from a digital parts library.
The design file is then divided into slices or layers for 3D printing using specific build preparation software, generating path instructions for the 3D printer to follow.
Below, you will learn the differences between these technologies and the typical uses of each.
Why are there 7 types?
Types of additive manufacturing can be categorized by the products they produce or the types of materials they use. The International Organization for Standardization (ISO) has divided them into seven general types (although these seven 3D printing categories barely cover the growing number of subtypes and hybrid technologies).
- Material Extrusion
- Vat photopolymerization
- Powder Bed Fusion
- Blasting of materials
- Binding blasting
- Directed energy deposition
- Sheet Lamination
I. Material Extrusion
As the name suggests, material extrusion involves extruding material through a nozzle.
Typically, this material is a plastic filament that is melted and extruded through a heated nozzle. The printer places the material on the build platform along the process path obtained through the software. The filament then cools and solidifies into a solid object. This is the most common form of 3D printing.
It may seem simple at first glance, but considering extruded materials including plastic, metal, concrete, biogels and various foods, it is actually a very broad category. The price of this type of 3D printer ranges from $100 to seven figures.
- Material extrusion subtypes: Fused Deposition Modeling (FDM), Construction 3D Printing, Micro 3D Printing, Bio 3D Printing.
- Materials: 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: Lowest cost 3D printing method, wide variety of materials.
- Disadvantages: Typically lower material performance (resistance, durability, etc.), generally without high dimensional accuracy.
1. Fused Deposition Modeling (FDM)
The FDM 3D printer market is worth billions of dollars, with thousands of machines ranging from basic models to complex manufacturer models. FDM machines are called Fused Filament Fabrication (FFF), which is entirely the same technology.
Like all 3D printing technologies, FDM starts with a digital model and then converts it into a path that the 3D printer can follow. With FDM, a filament (or several filaments at the same time) from a spool of thread is loaded into the 3D printer and then fed into the printer's nozzle on the extrusion head.
The printer's nozzle or multiple nozzles are heated to the temperature needed to soften the filament, allowing the continuous layers to 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 place the first layer. The extrusion head then rises to the next height (Z plane) and repeats the cross-section printing process, building layer by layer until the object is fully formed.
Depending on the geometry of the object, it may sometimes be necessary to add support structures to support the model during printing, for example if the model has steep overhangs. These supports are removed after printing. Some support structure materials may dissolve in water or other solution.
2. 3D Bioprinting
3D bioprinting, or 3D bioprinting, is an additive manufacturing process where organic or biological materials (such as living cells and nutrients) are combined to create natural three-dimensional tissue-like structures.
In other words, bioprinting is a form of 3D printing that can produce anything from skeletal tissue and vessels to living tissue. It is used for a variety of research and medical applications, including tissue engineering, drug testing and development, and innovative regenerative medical therapies. The actual definition of 3D bioprinting is still evolving.
Essentially, 3D bioprinting works similarly to FDM 3D printing and belongs to the extrusion series of materials (although extrusion is not the only bioprinting method).
3D bioprinting uses material (bioink) ejected from needles to create printed layers. These materials, known as bioinks, consist primarily of living matter such as cells in carrier materials – such as collagen, gelatin, hyaluronic acid, silk, alginate or nanocellulose, acting as molecular scaffolds for structural growth and nutrients providing support.
3. Architectural 3D printing
Architectural 3D printing is a rapidly advancing field in material extrusion. This technology involves using gigantic 3D printers, often several meters tall, to extrude building materials like concrete from a nozzle.
These machines typically appear in gantry or robotic arm systems. Today, 3D architectural printing technology is used in housing, architectural features, and various construction projects, from wells to walls. Researchers suggest it has the potential to significantly transform the entire construction industry by reducing demand for labor and minimizing construction waste.
There are dozens of 3D-printed homes in the United States and Europe, and research is being conducted into 3D construction technology that would use materials found on the Moon and Mars to build habitats for future explorers. Replacing concrete printing with local soil as a more sustainable construction method is also gaining attention.
II. Resin Aggregation
Vat polymerization (also known as resin 3D printing) is a series of 3D printing processes that selectively cures (or hardens) photosensitive polymer resin in a vat using a light source. In other words, the light is precisely directed to specific points or areas of the liquid plastic to harden it.
After the first layer has cured, the build platform moves slightly up or down (depending on the printer), usually between 0.01 and 0.05 millimeters, and the next layer is cured and connected to the previous one.
This process is repeated layer by layer until a 3D part is formed. After the 3D printing process is complete, the object is cleaned to remove any remaining liquid resin and post-cured (in sunlight or in a UV chamber) to improve the mechanical properties of the part.
The three most common forms of vat polymerization are stereolithography (SLA), digital light processing (DLP), and liquid crystal display (LCD), also known as masked stereolithography (MSLA). The fundamental difference between these types of 3D printing technologies lies in the light source and the way it is used to cure the resin.
Several 3D printer manufacturers, especially those that produce professional-grade 3D printers, have developed unique and patented variations of light curing, so you may see different technology names on the market.
Industrial 3D printer manufacturer Carbon uses a vat polymerization technology called Digital Light Synthesis (DLS), Stratasys' Origin calls its technology Programmable Photopolymerization (P3), Formlabs offers its technology called Low Force Stereolithography (LFS), and Azul 3D is the first to commercialize large-scale vat polymerization in a form called High Area Rapid Printing (HARP).
Other technologies include Lithography-Based Metal Fabrication (LMM), Projection Micro Stereolithography (PμSL), and Digital Composite Fabrication (DCM), a filled photopolymer technology that introduces functional additives (such as metallic and ceramic fibers) into the liquid resin.
- Types of 3D printing technologies: Stereolithography (SLA), Liquid Crystal Display (LCD), Digital Light Processing (DLP), Micro Stereolithography (μSLA), etc.
- Materials: Photopolymeric resins (moldable, transparent, industrial, biocompatible, etc.)
- Dimensional accuracy: ±0.5% (with lower limit of ±0.15 mm or 5 nm, using μSLA)
- Common Applications: Injection mold-like polymer prototypes and end-use parts, jewelry casting, dental applications, consumer goods
- Advantages: Smooth surface finishes, fine details.
1. Stereolithography (SLA)
Stereolithography, or SLA, is the world's first 3D printing technology. Invented in 1986 by Chuck Hull, who patented the technology and founded 3D Systems to commercialize it, SLA is now available to enthusiasts and professionals from several 3D printer manufacturers.
The process involves directing a laser beam into a container of resin, selectively solidifying cross-sections of the object within the print area in a layer-by-layer construction. Most SLA printers use a solid-state laser to solidify parts.
A disadvantage of this vat polymerization is that, compared to our next method (DLP), point lasers can take longer to trace the cross section of the object, which emits light to instantly harden the entire layer. However, lasers can produce stronger light, which is necessary for some engineering-grade resins.
(1) Microstereolithography (μSLA)
Microstereolithography technology can print miniature parts with resolution between 2 micrometers (μm) and 50 μm. For reference, the average width of a human hair is 75 μm. It is one of the “3D micro printing” technologies.
μSLA involves exposing photosensitive material (liquid resin) to an ultraviolet laser. What sets it apart is the specialized resin, the complexity of the laser, and the addition of lenses that produce incredibly small points of light.
(2) Two-Photon Polymerization (TPP)
Another 3D microprinting technology, TPP (also known as 2PP), can be categorized under SLA because it also uses laser and photosensitive resin. It can print parts smaller than μSLA, as small as 0.1 μm. TPP uses a pulsed femtosecond laser focused on a narrow spot inside a large tank of special resin.
This point is then used to solidify single 3D pixels, or voxels, within the resin. These tiny voxels, ranging from nano to micro in size, are solidified layer by layer along a predefined path. TPP is currently used in research, medical applications and in the manufacture of microparts such as microelectrodes and optical sensors.
2. Digital Light Processing (DLP)
DLP 3D printing uses a digital light projector (instead of a laser) to display the image of each layer (or multiple exposures for larger parts) on a resin layer or container. DLP (more common than SLA) is used to produce larger parts or larger volumes of parts in a single batch as exposing each layer takes the same time regardless of the number of parts in the build, making it more efficient than than the point. laser method in SLA.
The image of each layer is made up of square pixels, resulting in a layer made up of small rectangular blocks called voxels. Light is projected onto the resin using a light-emitting diode (LED) screen or a UV light source (lamp) and is projected onto the build surface via a digital micromirror device (DMD).
Modern DLP projectors typically have thousands of micro-sized LEDs as light sources. Their on/off states are controlled individually, increasing XY resolution. Not all DLP 3D printers are the same, with significant differences in the power of the light source, the lenses it passes through, the quality of the DMD, and many other components that make up a machine worth $300 compared to others that are. more than $200,000.
Top-down DLP
Some DLP 3D printers mount the light source on top of the printer, shining down into the resin container rather than upwards. These “top-down” machines display an image of a layer from above, solidifying one layer at a time and then returning the solidified layer to the large tank.
Each time the build platform is lowered, a recoater mounted on top of the large container moves back and forth through the resin to even out the new layer. Manufacturers claim this method produces more stable part results for larger prints because the printing process does not fight gravity.
There are limits to the amount of weight that can be suspended vertically from the build plate during bottom-up printing. The resin vat also supports the piece during printing, reducing the need for support structures.
Projection microstereolithography (PμSL)
As a distinct type of vat polymerization, PμSL is classified under DLP as a subcategory. It is another 3D micro printing technology. PμSL uses ultraviolet light from a projector to solidify layers of a special formula resin at the micron scale (2 μm resolution and layer height as low as 5 μm).
This additive manufacturing technology is evolving due to its low cost, precision, speed, and variety of usable materials (including polymers, biomaterials, and ceramics). It has shown potential for applications from microfluidics and tissue engineering to microoptics and biomedical microdevices.
Lithography-based metal fabrication (LMM)
This distant relative of DLP is a light-and-resin 3D printing method that can create small metal parts for applications such as surgical tools and micromechanical parts. In LMM, metal powder is uniformly dispersed in a photosensitive resin, which is selectively polymerized through exposure to blue light from a projector.
After printing, the polymeric component of the green part is removed, leaving an unbound, all-metallic part that is finished in an oven sintering process. Raw materials include stainless steel, titanium, tungsten, brass, copper, silver and gold.
3. Liquid Crystal Display (LCD)
Liquid Crystal Display (LCD), also known as Masked Stereolithography (MSLA), is very similar to the aforementioned DLP. The difference lies in the use of an LCD screen instead of a Digital Micromirror Device (DMD), which significantly affects the price of 3D printers.
Like DLP, the LCD light mask is displayed digitally and is made up of square pixels. The size of the pixels in the LCD light mask determines the granularity of the print. As such, XY accuracy is fixed and does not depend on the zoom degree or lens scaling, 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 light source such as laser diodes or DLP lamps.
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 unit cost of LCDs, this technology has become the preferred technology in the field of low-cost desktop resin printers. However, this does not mean that it is not used professionally. Some industrial 3D printer manufacturers are pushing technological boundaries and achieving impressive results.
III. Powder Bed Fusion
Powder bed fusion (PBF) is a 3D printing process in which a thermal energy source selectively melts powder particles (plastic, metal, or ceramic) within the build area to create solid objects layer by layer.
A PBF 3D printer disperses a thin layer of powdered material onto the print bed, typically using a blade, roller or wiper. Energy from a laser fuses specific points of the powder layer, and then another layer of powder is deposited and fused to the previous layer. This process is repeated until the entire object is manufactured, with the final product surrounded and supported by unmolten powder.
PBF can produce parts with high mechanical performance (including strength, wear resistance and durability) for end use in consumer goods, machines and tools. 3D printers in this submarket are becoming cheaper (starting at around $25,000) but are considered an industrial technology.
- Types of 3D printing technology: Selective laser sintering (SLS), laser powder bed fusion (LPBF), electron beam melting (EBM)
- Materials: Plastic powder, metal powder, ceramic powder
- Dimensional accuracy: ±0.3% (lower limit ±0.3 mm)
- Common applications: Functional parts, complex piping (hollow design), small batch production of parts
- Advantages: Functional parts, excellent mechanical performance, complex geometric shapes
- Disadvantages: High machine costs, typically high-cost materials, slow construction speed
1. Selective Laser Sintering (SLS)
Selective Laser Sintering (SLS) uses a laser to make objects from plastic powder. First, a box of polymer powder is heated to just below the polymer's melting point. Next, a recoating blade or wiper deposits a very thin layer of powdered material (usually 0.1 mm thick) onto the build platform.
The laser begins scanning the surface according to the pattern shown on the digital model. The laser selectively sinters the powder and solidifies the cross-section of the object. By scanning the entire cross section, the build platform drops one layer thickness. The recoating blade deposits a new layer of powder onto the most recently scanned layer and the laser sinters the next cross-section of the object onto the previously solidified cross-section.
These steps are repeated until all objects are manufactured. The unsintered powder remains in place to support the object, reducing or eliminating the need for support structures. Once the part is removed from the powder bed and cleaned, no other necessary post-processing steps are required.
The piece can be polished, coated or colored. There are many differentiating factors between SLS 3D printers, not only the size, but also the power and number of lasers, the laser spot size, the time and way of heating the bed, and the distribution of the powder. The most common material in SLS 3D printing is nylon (PA6, PA12), but TPU and other materials can also be used to print flexible parts.
2. Microselective Laser Sintering (μSLS)
μSLS belongs to the SLS or Laser Powder Bed Fusion (LPBF) technology mentioned below. It uses a laser to sinter powdered material like SLS, but that material is typically metal rather than plastic, so it's more similar to LPBF. It is another 3D micro printing technology that can create parts with micro resolution (below 5 μm).
In μSLS, a layer of metal nanoparticle ink is coated onto the substrate and then dried to produce a uniform layer of nanoparticles. Then, a patterned laser from an array of digital micromirrors is used to heat the nanoparticles and sinter them into the desired pattern. This set of steps is repeated to build each layer of the 3D part in the μSLS system.
3. Laser Powder Bed Fusion (LPBF)
Among all 3D printing technologies, this one has the most aliases. The formal name of this metal 3D printing method is Laser Powder Bed Fusion (LPBF), but it is also widely known as Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM).
Early in the development of this technology, machine manufacturers created their own names for the same process, and these names have been used ever since. Notably, the three terms above refer to the same process, even if some mechanical details are different.
As a subtype of powder bed fusion, LPBF utilizes a metal powder bed and one or more (up to 12) high-power lasers. LPBF 3D printers use lasers to selectively fuse metal powders on a molecular basis, layer by layer, until the model is complete. LPBF is a highly precise 3D printing method typically used to create complex metal parts for aerospace, medical and industrial applications.
Like the SLS, LPBF 3D printers start with a digital model divided into slices. The printer loads the powder into the build chamber and then uses a scraper (like a windshield wiper) or roller to spread it in a thin layer on the build plate. The laser traces the layer onto the powder.
Then the build platform lowers, another layer of powder is applied and fused with the first layer until the entire object is built. The build chamber is closed, sealed, and often filled with an inert gas mixture, such as nitrogen or argon, to ensure that the metal does not oxidize during the melting process and helps clean debris from the melting process.
After printing, the part is removed from the powder bed, cleaned, and often undergoes secondary heat treatment to eliminate stress. The remaining powder is recycled and reused.
Differentiating factors of LPBF 3D printers include the type, resistance and number of lasers. Small, compact LPBF printers may have one 30-watt laser, while industrial versions may 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.
4. 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 fiber laser. This technology is used in the manufacture of parts such as titanium orthopedic implants, turbine blades for jet engines and copper coils.
The electron beam generates more energy and heat, which are necessary for some metals and applications. Furthermore, EBM is not an inert gas environment, but is performed in a vacuum chamber to prevent beam scattering. The temperature of the build chamber can reach up to 1,000 °C, and even higher in some cases. Because the electron beam uses electromagnetic beam control, its movement speed is faster than that of the laser and can even be split to expose multiple areas simultaneously.
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 its ability to nest or stack separate parts within the build chamber, as they do not necessarily need to be clamped to the build plate, significantly increasing volume production.
Compared to lasers, electron beams generally produce thicker layers and rougher surfaces. Due to the high temperature in the build chamber, EBM printed parts may not require post-print heat treatment to eliminate stress.
4. Blasting of materials
Material jetting is a 3D printing process where small droplets of material are deposited and then solidified or cured on a build plate. This process uses a photosensitive polymer or wax droplets that solidify when exposed to light, building objects one layer at a time.
The nature of the material blasting process allows different materials to be printed on the same object. One application of this technology is the manufacture of parts with different colors and textures.
- Types of 3D printing technology: Material jetting (MJ), Nanoparticle jetting (NPJ)
- Materials: Photosensitive resin (standard, cast, transparent, high temperature resistant), wax
- Dimensional accuracy: ±0.1mm
- Common applications: Color product prototypes, injection mold-like prototypes, low-yield injection molds, medical models, fashion
- Advantages: Smooth, colorful surface texture and various materials available
- Disadvantages: Limited materials, not suitable for precision mechanical parts, more expensive than other resin technologies used for visual purposes
1. Material Blasting (M-Jet)
Polymer Material Jetting (M-Jet) is a 3D printing process where a layer of photosensitive resin is selectively deposited on a build plate and cured using ultraviolet (UV) light.
After a layer is deposited and cured, the build platform drops one layer thickness and the process is repeated to build a 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.
All material jet 3D printing technologies are not completely identical. There are differences between printer manufacturers and proprietary materials. M-Jet machines deposit construction materials line by line from multiple rows of print heads.
This method allows the printer to manufacture multiple objects in one line without affecting construction speed. As long as the model is correctly arranged on the build platform and space within each build line is optimized, the M-Jet can produce parts faster than many other types of resin 3D printers.
Objects manufactured with M-Jet require support, which is simultaneously printed with soluble material during the construction process and removed in the post-processing phase. M-Jet is one of the few 3D printing technologies that offers objects made from multi-material, full-color printing.
Material blasting machines are not available in amateur versions; These machines are best suited for automotive manufacturing professionals, industrial design firms, art studios, hospitals, and all types of product manufacturers who want to create accurate prototypes to test concepts and bring products to market faster.
Unlike vat polymerization technology, M-Jet does not require post-curing as the UV light in the printer completely cures each layer.
Aerosol Blasting
Optomec has developed Aerosol Jet, a unique technology used primarily for 3D printing of electronic products. Thin film resistors, capacitors, antennas, sensors and transistors are all printed using Aerosol Jet technology. It can be roughly compared to spray painting, but it differs from industrial coating processes in that it can be used to print complete 3D objects.
The electronic ink is placed in an atomizer, which produces droplets with diameters between 1 and 5 microns. The aerosol mist is then delivered to the deposition head, focused by a sheath gas, creating a high-velocity spray of particles.
Since the entire process uses energy, this technology is also sometimes called Directed Energy Deposition, but since the material in this case is in the form of droplets, we include it in material blasting.
Freeform Plastic Molding
German company Arburg has created a technology called free-form plastic molding (APF), a combination of extrusion and material blasting technologies. It uses commercially available plastic granules, which are melted in the injection molding process and transported to the discharge unit.
Rapid opening and closing movement of the high-frequency nozzle, producing up to 200 plastic drops per second with diameters between 0.2 and 0.4 mm. The droplets attach to the solidifying material during cooling. Post-processing is generally not necessary. If support material was used, it must be removed.
2. Nanoparticle jetting (NPJ)
NanoParticle Jetting (NPJ) is one of the few difficult-to-classify proprietary technologies developed by a company called XJet. It uses a set of print heads with thousands of inkjet nozzles that can simultaneously inject millions of droplets of ultra-fine material into a super-thin layer of the build tray while also injecting support material.
Metallic or ceramic particles remain suspended in the liquid. The process takes place at high temperatures, where the liquid evaporates when blasted, leaving mainly metallic or ceramic material. The resulting 3D parts have only a small amount of binding agent, which is removed in the sintering post-processing.
V. Binding blasting
Binder jetting is a 3D printing process that selectively bonds a layer of powder to specific areas using a liquid adhesive. This type of technology combines the characteristics of powder bed fusion and material blasting.
Similar to PBF, binder blasting uses powdered material (metals, plastics, ceramics, wood, sugar, etc.) and, like material blasting, liquid adhesive polymer is deposited from a paint jet. The binder blasting process remains the same whether it is metal, plastic, sand or other powdered materials.
First, a coating blade spreads a thin layer of powder onto the build platform. Then, a print head equipped with an inkjet nozzle passes over the base, selectively depositing droplets of adhesive to bind the powder particles together. Once the layer is complete, the build platform moves down and the blade re-coats the surface. This process is repeated until the entire piece is finished.
The uniqueness of the binder jet lies in the absence of heat during the printing process. The adhesive acts as a glue that holds the polymer powder together. After printing, the part is encased in unused powder, which is typically left to solidify. The part is then removed from the dust container, the excess dust is collected and can be reused.
From here, post-processing is necessary depending on the material, except sand, which can generally be used directly from the printer as a core or mold. When the powder is metallic or ceramic, post-processing involving heat melts the adhesive, leaving only the metal. Post-processing of plastic parts often includes coating to improve surface smoothness. Polishing, painting and sanding can also be done on polymer binder jet parts.
Binder blasting is fast and has a high production rate, so compared with other AM methods, it can produce a large number of parts more cost-effectively. Metal binder blasting is applicable to a variety of metals and is popular in end-use consumer goods, tools and batch spare parts.
However, the selection of materials for blasting polymeric binders is limited and the structural performance of the parts produced is inferior. Its value lies in the ability to create colorful prototypes and models.
- 3D Printing Technology Subtypes: Metal Binder Blasting, Polymer Binder Blasting, Sand Binder Blasting
- Materials: Sand, polymers, metals, ceramics, etc.
- Dimensional accuracy: ±0.2 mm (metal) or ±0.3 mm (sand)
- Common applications: Functional metal parts, color models, sand castings and molds
- Advantages: Low cost, large build volume, functional metal parts, excellent color reproduction, fast printing speed, stand-free design flexibility
- Disadvantages: It is a multi-step process for metals, polymer parts are not durable
1. Metal Binder Blasting
Binder Jetting can also be used to manufacture solid metal objects with complex geometric shapes, far beyond the capabilities of traditional manufacturing technologies. Metal binder blasting is a very attractive technology for mass producing metal parts and achieving light weight.
Because binder jetting can print parts with complex pattern fills rather than solids, the resulting parts are significantly lighter but maintain their strength. The porosity characteristics of the binder jet can also be used to create lighter end parts for medical applications such as implants.
In general, the material performance of metal binder blasted parts is comparable to that of metal parts produced using metal injection molding, one of the most widely used manufacturing methods in mass production of metal parts. Furthermore, parts blasted with binder have greater surface smoothness, especially in internal channels.
Metal binder blasted parts need secondary processing after printing to obtain good mechanical properties. Fresh from the printer, the parts essentially consist of metallic particles held together by a polymer binder.
These so-called “green parts” are too fragile to be used as is. After the printed parts are removed from the metal powder bed (a process called depulverization), they undergo heat treatment (a process called sintering) in an oven.
Both printing parameters and sintering parameters are adjusted to the specific geometry, material and required density of the part. Sometimes bronze or other metals are used to infiltrate the voids in binder blasted parts, thereby achieving zero porosity.
2. Plastic paste blasting
Plastic binder blasting is a process very similar to metallic binder blasting, as it also uses powder and liquid binder, but the applications are very different. Once printing is complete, the plastic parts are removed from the powder bed and cleaned, generally ready for use without additional processing, but these parts lack the strength and durability found in other 3D printing processes.
Parts blasted with plastic binder can be infused with another material to increase their strength. Binder blasting with polymers is preferred for its ability to produce multicolored parts for medical modeling and product prototyping.
3. Sand blasting with adhesive
Adhesive sand blasting differs from plastic adhesive blasting in terms of the printing machine and process used, hence the separation. One of the most common uses of adhesive jet technology is the production of large molds, models and cores for sand casting. The low cost and speed of this process make it an excellent solution for foundries, as it is challenging to produce complex pattern designs in a few hours using traditional technologies.
The future of industrial development constantly places high demands on contractors and suppliers. 3D sand printing is just beginning to explore its potential. After printing, the operator needs to remove the cores and molds from the construction area and clean them to remove any loose sand. Molds can usually be prepared for casting immediately. After casting, the mold is opened and the final metal part is removed.
4. Multijet Fusion (MJF)
Another unique, brand-specific 3D printing process that doesn't easily fit into any existing category, and in fact isn't adhesive jetting, is HP's Multi Jet Fusion. MJF is a polymer 3D printing technology that uses powder material, liquid fusion material and a detailing agent.
It is not considered adhesive blasting because heat is added in this process, producing parts with greater strength and durability, and the liquid is not entirely an adhesive. The name of this process comes from the various inkjet heads used in the printing process.
During the Multi Jet Fusion printing process, the printer places a layer of powdered material, usually nylon, on the print bed. After that, the inkjet heads pass over the powder and deposit the fusing agent and detailing agent into it. An infrared heating device moves over the print. Wherever the fusing agent is added, the underlying layers fuse, while the areas with the detailing agent remain powdery.
The powdery parts fall, producing the desired geometric shape. This also eliminates the need for modeling support, as the bottom layers support the layers printed on top of them. To complete the printing process, the entire powder bed and the printed parts within it are moved to a separate processing station, where most of the loose, unmelted powder is vacuumed up for reuse.
Multi Jet Fusion is a versatile technology that has been applied across multiple industries, including automotive, healthcare and consumer goods.
SAW. Powder directed energy deposition
Directed Energy Deposition (DED) is a 3D printing process where metallic material is supplied and melted simultaneously with a powerful supply of energy. It is one of the broadest categories of 3D printing, encompassing many subcategories depending on the form of the material (wire or powder) and the type of energy (laser, electron beam, arc, supersonic, thermal, etc.). Essentially, it has many similarities to welding.
This technology is used for layer-by-layer printing, often followed by CNC machining to achieve tighter tolerances. The combination of DED and CNC is very common, and there is a subtype of 3D printing called Hybrid 3D Printing, which includes DED and CNC units on the same machine.
This technology is considered a faster, cheaper alternative to small-batch metal casting and forging, and a key fix for applications in the offshore oil and gas industry, as well as the aerospace, power generation and utility sectors.
- Subtypes of Directed Energy Deposition: Powder laser energy deposition, wire arc additive manufacturing (WAAM), wire electron beam energy deposition, cold spray coating
- Materials: Various metals, wire and powder
- Dimensional accuracy: ±0.1mm
- Common Applications: Repair of high-quality automotive/aerospace parts, functional prototypes and final parts
- Advantages: High deposition rate, ability to add metal to existing components
- Disadvantages: It is not possible to produce complex shapes due to the inability to make supporting structures, usually with worse surface finish and precision.
1. Laser-directed energy deposition
Laser Directed Energy Deposition (L-DED), also known as Laser Metal Deposition (LMD) or Laser Engineered Network Shaping (LENS), uses metal powder or wire delivered through one or more nozzles and melted on a building platform or metal part by a powerful laser. As the nozzle and laser move, or the part moves on a multi-axis turntable, the object is built layer by layer.
The build speed is faster than powder bed fusion, but results in reduced surface quality and significantly reduced accuracy, typically requiring substantial post-processing. DED laser printers typically have a sealed chamber filled with argon gas to prevent oxidation. When handling less reactive metals, they can operate using only local argon or nitrogen gas.
Common metals used in this process include stainless steel, titanium, and nickel alloys. This printing method is typically used to repair high-quality aerospace and automotive parts, such as jet engine blades, but is also used to produce entire parts.
2. Electron Beam Directed Energy Deposition
Electron Beam DED, also known as Wire Electron Beam Energy Deposition, is a 3D printing process very similar to Laser DED. It is conducted in a vacuum chamber and can produce very clean, high-quality metals. As a metal wire passes through one or more nozzles, it is melted by a beam of electrons.
The layers are built individually, with the electron beam forming a small weld pool into which the wire is fed by a wire feeder. When handling active, high-performance metals (such as copper, titanium, cobalt and nickel alloys), the electron beam is chosen for DED.
DED machines are effectively unlimited in terms of print size. For example, 3D printer manufacturer Sciaky has an EB DED machine capable of producing parts nearly 20 feet long at a rate of 3 to 9 kilograms of material per hour.
Electron Beam DED is touted as one of the fastest methods for manufacturing metal parts, although it is not the most accurate, making it an ideal machining technology for building large structures (such as fuselages) or replacement parts (such as turbine blades).
3. Wire-directed energy deposition
Wire Directed Energy Deposition, also known as Wire Arc Additive Manufacturing (WAAM), is a form of 3D printing that uses energy in the form of plasma or electric arc to melt metal into the form of wire, which is then deposited layer layered on a surface, such as a multi-axis turntable, by a robotic arm to form a shape.
This method is chosen over similar technologies that use lasers or electron beams because it does not require a sealed chamber and can use metals identical to those used in traditional welding (sometimes even exactly the same material).
Direct Electrical Energy Deposition is considered the most economical choice in DED technology as it can use robots and existing arc welding power sources, making the barrier to entry relatively low.
Unlike welding, however, this technique uses complex software to control a variety of variables during the process, including heat management and robotic arm tool paths. This technique has no support structures to remove, and finished parts are commonly CNC machined when necessary to achieve tight tolerances or surface polishing.
4. Cold spray coating
Cold Spray Coating is a DED 3D printing technology that uses supersonic spraying of metal powders to bond them together without melting, virtually eliminating thermal cracking or stress.
Since the early 2000s, it has been used as a coating process, but recently several companies have started using cold spray coating for additive manufacturing because it can print at speeds 50 to 100 times faster than typical 3D metal processes and does not require inert gas or a vacuum chamber.
Like all DED processes, Cold Spray Coating does not produce prints with good surface quality or detail, but parts can be used directly from the print bed.
5. Fusion-directed energy deposition
Fusion-directed energy deposition is a 3D printing process that uses heat to melt metal (usually aluminum), which is then deposited layer by layer on a build plate to form a 3D object. The difference between this technology and metal extrusion 3D printing is that extrusion uses metallic raw material with a small amount of polymer inside, allowing the metal to be extruded.
The polymer is then removed in a heat treatment step, while Melt DED uses pure metal. Molten or liquid DED can also be compared to material jetting, but instead of a series of nozzles depositing droplets, the liquid metal typically flows out of a nozzle.
Variations of this technology are being developed and Melt Metal 3D printers are rare. The advantage of using heat to melt and then deposit metal is that it uses less energy than other DED processes and can potentially use recycled metal as a raw material rather than highly processed metal wire or metal powder.
VII. Sheet Lamination
Foil lamination is technically a form of 3D printing, but it differs significantly from the techniques mentioned above. Its function is to stack and laminate sheets of very thin materials to produce 3D objects or stacks, which are then cut mechanically or by laser to form the final shape.
Layers of material can be fused using various methods, including heat and sound, depending on the material, with materials ranging from paper and 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 thin sheet lamination to produce non-functional prototypes at a relatively high speed and cost-effectiveness, suitable for battery technology and composite materials production as the materials used can be changed during the process Printing.
- Types of 3D printing technology: Laminated Object Manufacturing (LOM), Ultrasonic Consolidation (UC)
- Materials: Paper, polymers and metal sheets
- Dimensional accuracy: ±0.1mm
- Common applications: Non-functional prototypes, multi-color printing, casting molds.
- Advantages: Fast production, composite printing
- Disadvantages: Low precision, high waste, some parts require post-production
Laminated Additive Manufacturing
Lamination is a form of 3D printing technology in which sheets of material are stacked and glued together, and then the layered object is cut into the correct shape using a knife (or laser or CNC router). This technology is less common today, as the cost of other 3D printing technologies has decreased and their speed and ease of use have increased significantly.
Viscous Lithography Manufacturing (VLM): VLM is BCN3D's patented 3D printing process that laminates thin layers of high-viscosity photosensitive resin onto a transparent transfer film. The mechanical system allows the resin to be laminated on both sides of the film, enabling the combination of different resins to obtain multi-material parts and easily removable support structures. This technology has not yet been commercialized, but can be considered a type of laminated 3D printing technology.
Composite-Based Additive Manufacturing (CBAM): Start-up Impossible Objects has patented this technology, which fuses pads of carbon, glass or Kevlar with thermoplastic plastic to make parts.
Selective Lamination Composite Material Manufacturing (SLCOM): EnvisionTEC, now known as ETEC and owned by Desktop Metal, developed this technology in 2016, which uses thermoplastic plastic as the base material and woven fiber composite material.
Note: There are many types of 3D printing technologies; The above are the seven most common types of additive manufacturing technologies in 3D printing and do not cover all 3D printing technologies on the market.
