The types of 3D Printing Process could be divided by what they produce or which type of material they use, but to apply structure to the technology worldwide, the International Standards Organization (ISO) divided them into seven general types:
- Material Extrusion.
- Vat Polymerization.
- Powder Bed Fusion.
- Material Jetting.
- Binder Jetting.
- Directed Energy Deposition.
- Sheet Lamination.
But even these seven 3D printing categories struggle to encompass the growing variety of technology subtypes and hybrids. Below, we cover it all!
#1. Material Extrusion.
Material extrusion is an additive manufacturing (AM) methodology. A spool of material (usually thermoplastic polymer) is pushed through a heated nozzle in a continuous stream and selectively deposited layer by layer to build a 3D object.
Fused filament fabrication (FFF) and fused deposition modeling (FDM) are two examples of material extrusion technology.
Material extrusion is typically not as fast or accurate as other types of additive manufacturing. However, material extrusion technology and compatible raw materials, like nylon and ABS plastic, are widespread and inexpensive.
In manufacturing and industrial settings, material extrusion is commonly used for producing non-functional prototypes, temporary replacement parts for machinery, or cost-effective rapid prototyping for multiple iterations of the same object.
Fused Deposition Modeling (FDM).
Fused deposition modeling (FDM) 3D printing, also known as fused filament fabrication (FFF), is an additive manufacturing (AM) process within the realm of material extrusion.
An FDM 3D printer works by depositing melted filament material over a build platform layer by layer until you have a completed part.
FDM uses digital design files that are uploaded to the machine itself and translates them into physical dimensions.
Materials for FDM include polymers such as ABS, PLA, PETG and PEI, which the machine feeds as threads through a heated nozzle.
FDM builds parts layer by layer by selectively depositing melted material in a predetermined path. It uses thermoplastic polymers that come in filaments to form the final physical objects.
Composing the largest installed base of 3D printers worldwide, FDM is the most widely used technology across most industries, and likely the first process you think of when 3D printing comes up.
3D Bioprinting.
3D bioprinting is an additive manufacturing process that uses bioinks to print living cells developing structures layer-by-layer which imitate the behavior and structures of natural tissues.
Bioinks, that are used as a material in bioprinting, are made of natural or synthetic biomaterials that can be mixed with living cells.
The technology and bioprinted structures enable researchers to study functions of the human body in vitro. 3D bioprinted structures are more biologically relevant compared to in vitro studies performed in 2D.
Mostly, 3D bioprinting can be used for several biological applications in the fields of tissue engineering, bioengineering and materials science.
The technology is also increasingly used for pharmaceutical development and drug validation. Clinical settings such as 3D printed skin and bone grafts, implants and even full 3D printed organs are currently at the center of bioprinting research.
Construction 3D Printing.
3D construction printing (3DCP or 3DP) refers to the automated process of manufacturing construction elements or entire structures by means of a 3D printer.
However, instead of using ink like the traditional printers we’re used to, construction materials are printed layer-upon-layer, which is also why 3DCP goes by the name additive manufuacturing or additive construction. It can be carried out both onsite and offsite.
The technology around 3D printing has been questioned many times since the 1980s.
However, it has gained greater relevance thanks to the improvement of the technique itself that allows for the creation of a three-dimensional object by superimposing successive layers of material.
This method of construction is very versatile and can help create specific components of a project and even various types of complex structures in its entirety such as houses or living spaces, offices, bridges, walls, modular structures, reinforcement molds, columns, urban furniture and even decorative elements.
#2. Vat Polymerization.
Vat Polymerization also known as Vat photopolymerization is a category of additive manufacturing (AM) processes that create 3D objects by selectively curing liquid resin through targeted light-activated polymerization.
Stereolithography, the first AM process to be patented and commercialized, is a vat photopolymerization technique.
Since the advent of stereolithography in the 1980s, vat photopolymerization has grown to also include continuous liquid interface production (CLIP), solid ground curing (SGC), and direct light processing (DLP).
All types of vat photopolymerization use special resins called photopolymers as the printing material.
When exposed to certain wavelengths of light, the liquid photopolymers’ molecules rapidly bind together and cure into a solid state through a process called photopolymerization.
Stereolithography (SLA).
Stereolithography (SLA) or Resin 3D Printing is an additive manufacturing process where a light source cures liquid resin into hardened plastic.
Stereolithography (SLA) is used for creating models, prototypes, patterns, and production parts in a layer-by-layer fashion using photochemical processes by which light causes chemical monomers and oligomers to cross-link together to form polymers.
Stereolithography can be used to create prototypes for products in development, medical models, and computer hardware, as well as in many other applications. While stereolithography is fast and can produce almost any design, it can be expensive.
Digital Light Processing (DLP).
DLP (Digital Light Processing) is a 3D printing technology used to rapidly produce photopolymer parts.
It’s very similar to SLA with one significant difference where SLA machines use a laser that traces a layer, a DLP machine uses a projected light source to cure the entire layer at once. The part is formed layer by layer.
DLP printing can be used to print extremely intricate resin design items like toys, jewelry molds, dental molds, figurines and other items with fine details.
Due to it curing the entire layer at once, it’s much faster than SLA. DLP printers are popular for their ability to quickly produce objects and parts with intricate designs with a high degree of accuracy.
They are relatively affordable, so they are often found in offices. Limitations of DLP printing include strong odors produced by melting photopolymers in the printing process, and the risk of warping in larger items.
Liquid Crystal Display (LCD).
A 3D LCD printer is a type of printer that uses light-curing resin printing technology. Unlike traditional 3D printers, which print layer by layer, LCD 3D printers print an entire layer at once using UV light.
This means that 3D printing with a 3D LCD printer is faster and more precise than with other 3D printers.
The LCD 3D printer differs from other types of 3D printers, such as DLP or SLA printers, in its light source. LCD 3D printers use a UV LCD array as a light source.
As a result, the light from the LCD flat panels shines directly, in a parallel fashion, onto the work area. Since this light is not expanded, pixel distortion is much less of a problem with LCD printing.
#3. Material Jetting.
Material jetting creates objects in a similar method to a two-dimensional ink jet printer. Material is jetted onto a build platform using either a continuous or Drop on Demand (DOD) approach.
Material is jetted onto the build surface or platform, where it solidifies and the model is built layer by layer. Material is deposited from a nozzle which moves horizontally across the build platform.
Machines vary in complexity and in their methods of controlling the deposition of material. The material layers are then cured or hardened using ultraviolet (UV) light.
As material must be deposited in drops, the number of materials available to use is limited. Polymers and waxes are suitable and commonly used materials, due to their viscous nature and ability to form drops.
NanoParticle Jetting (NPJ).
NanoParticle Jetting (NPJ) is a 3D printing process developed and commercialized by Xjet. NPJ is a form of material jetting that uses suspensions of powdered material to build up parts.
Similar to binder jetting, however, parts typically go through a sintering step to remove bonding agent and achieve their final density.
NPJ jets a liquid that contains nanoparticles of metal or ceramic material in suspension to build up the part, while simultaneously jetting a support material.
The process takes place in a heated bed held at 250°C, which allows the liquid to evaporate upon jetting so that the particles adhere in all directions.
The resulting 3D object has only a small amount of bonding agent in its body and supports; to remove the binder and achieve its final density, a sintering step is also needed.
#4. Powder Bed Fusion.
The Powder Bed Fusion process includes the following commonly used printing techniques:
- Direct metal laser sintering (DMLS).
- Electron beam melting (EBM).
- Selective heat sintering (SHS).
- Selective laser melting (SLM).
- Selective laser sintering (SLS).
Powder bed fusion (PBF) methods use either a laser or electron beam to melt and fuse material powder together.
Electron beam melting (EBM), methods require a vacuum but can be used with metals and alloys in the creation of functional parts.
All PBF processes involve the spreading of the powder material over previous layers. There are different mechanisms to enable this, including a roller or a blade.
A hopper or a reservoir below of aside the bed provides fresh material supply. Direct metal laser sintering (DMLS) is the same as SLS, but with the use of metals and not plastics. The process sinters the powder, layer by layer.
Selective Heat Sintering differs from other processes by way of using a heated thermal print head to fuse powder material together.
As before, layers are added with a roller in between fusion of layers. A platform lowers the model accordingly.
Selective Laser Sintering (SLS).
Selective laser sintering is an additive manufacturing (AM) technology that uses a high-power laser to sinter small particles of polymer powder into a solid structure based on a 3D model.
SLS 3D printing has been a popular choice for engineers and manufacturers for decades.
Low cost per part, high productivity, and established materials makes the technology ideal for a range of applications from rapid prototyping to small-batch, bridge, or custom manufacturing.
Recent advances in machinery, materials, and software have made SLS printing accessible to a wider range of businesses, enabling more and more companies to use these tools that were previously limited to a few high-tech industries.
Laser Powder Bed Fusion (LPBF).
Laser powder bed fusion (LPBF) is a process similar to SLS but used for metals. A recoater blade or roller spreads powdered metal across a substrate and a laser beam is used to melt the powder needed for each layer.
In contrast to SLS, however, parts begin by being fused to the substrate and often require support structures to stabilize overhangs and help with thermal control.
Due to the combustible nature of the metal powders, LPBF is usually performed under inert gas such as argon, or under vacuum.
Again, unfused powder can often be reused in the process but may degrade over time due to oxidation.
Electron Beam Melting (EBM).
Electron beam melting (EBM) is a type of additive manufacturing for metal parts. It is often classified as a rapid manufacturing method. The technology manufactures parts by melting metal powder layer by layer with an EB in a high vacuum.
Electron Beam Melting (EBM) is a 3D manufacturing process in which a powdered metal is melted by a high-energy beam of electrons.
An electron beam produces a stream of electrons that is guided by a magnetic field, melting layer upon layer of powdered metal to create an object matching the precise specifications defined by a CAD model.
Production takes place in a vacuum chamber to guard against oxidation that can compromise highly reactive materials.
Electron Beam Melting is similar to Selective Laser Melting (SLM), as they both print from a powder from the 3D printer’s powder bed, but EBM uses an electron beam instead of a laser.
EBM builds high-strength parts that make the most of the native properties of the metals used in the process, eliminating impurities that may accumulate when using casting metals or using other methods of fabrication.
It is used to print components for aerospace, automotive, defense, petrochemical, and medical applications.
Selective heat sintering (SHS).
Selective heat sintering (SHS) is a type of additive manufacturing process. It works by using a thermal printhead to apply heat to layers of powdered thermoplastic.
When a layer is finished, the powder bed moves down, and an automated roller adds a new layer of material which is sintered to form the next cross-section of the model.
SHS is best for manufacturing inexpensive prototypes for concept evaluation, fit/form and functional testing.
SHS is a Plastics additive manufacturing technique similar to selective laser sintering (SLS), the main difference being that SHS employs a less intense thermal printhead instead of a laser, thereby making it a cheaper solution, and able to be scaled down to desktop sizes.
Direct Metal Laser Sintering (DMLS).
Direct metal laser sintering (DMLS) is a common 3D printing or additive manufacturing technique that is also referred to as selective laser melting (SLM).
In this process, each layer of a part is created by aiming a laser at the powder bed in specific points in space, guided by a digitally produced CAD (computer-aided design) file.
Once a layer is printed, the machine spreads more powder over the part and repeats the process. The process is ideal for printing precise, high-resolution parts with complex geometries.
DMLS machines use a laser to heat the particulate matter to its melting point in a digital process that eliminates the need for physical molds.
The resulting parts are accurate, have excellent surface quality and near-wrought mechanical properties.
DMLS printers are recommended when you want to print a limited number of industrial items that are otherwise difficult or impossible to fabricate because of hollow spaces, undercuts, challenging angles, and other complexities.
DMLS is ideal for low-volume parts and when you want to avoid the time and expense of creating a tooling.
DMLS parts can be stored digitally and printed on demand, which reduces inventory costs and increases design flexibility.
#5. Directed Energy Deposition.
Directed energy deposition is a broadly employed 3D printing technique for producing gradient-structured metals and alloys. This process utilizes an electric arc or laser to melt metals in the form of wires or powders.
Directed Energy Deposition (DED) covers a range of terminology: ‘Laser engineered net shaping, directed light fabrication, direct metal deposition, 3D laser cladding’ It is a more complex printing process commonly used to repair or add additional material to existing components.
A typical DED machine consists of a nozzle mounted on a multi axis arm, which deposits melted material onto the specified surface, where it solidifies.
The process is similar in principle to material extrusion, but the nozzle can move in multiple directions and is not fixed to a specific axis.
The material, which can be deposited from any angle due to 4 and 5 axis machines, is melted upon deposition with a laser or electron beam.
The process can be used with polymers, ceramics but is typically used with metals, in the form of either powder or wire.
Laser Directed Energy Deposition.
Laser-directed energy deposition (LDED) is an additive manufacturing (AM) process to build a component by delivering energy and material simultaneously.
A laser beam is used to melt material that is selectively deposited on a specified surface, where it solidifies.
Laser Directed Energy Deposition (L-DED), also called laser metal deposition (LMD) or Laser Engineered Net Shaping (LENS), is a 3D printing technology using a metal powder or wire fed through one or more nozzles and fused via a powerful laser on a build platform or on a metal part.
An object is built up layer by layer as the nozzle and laser move or as the part moves on a multiple-axis turntable.
The build rates are faster than powder bed fusion but result in lower surface quality and significantly lower accuracy, often requiring extensive post-machining.
Laser DED printers often have sealed chambers filled with argon to avoid oxidation. They also can operate with just a localized argon or nitrogen flood when processing less reactive metals.
Metals commonly used in this process include stainless steels, titanium, and nickel alloys.
This printing method is often used to repair high-end aerospace and automotive components, such as jet engine blades, but it is also used to produce entire components.
Electron Beam Directed Energy Deposition.
Electron beam DED, also called wire electron beam energy deposition, is a 3D printing process very similar to DED with a laser.
It is carried out in a vacuum chamber, which produces very clean, high-quality metal. As a metal wire is fed through one or more nozzles, it is fused by an electron beam.
Layers are built up individually, with the electron beam creating a tiny melt pool and the weld wire fed into the melt pool by a wire feeder.
Electron beams are chosen for DED when working with high-performance metals and reactive metals, such as alloys of copper, titanium, cobalt, and nickel.
Metal wire-fed DED using electron beams is faster than powder-fed. The process is carried out in a vacuum chamber.
DED machines are practically not limited in terms of print size. 3D printer manufacturer Sciaky, for example, has an EB DED machine that can produce parts nearly six meters long at a rate of 3 to 9 kilos of material per hour.
In fact, electron beam DED is touted as one of the fastest ways to build metal parts, although not the most precise, which makes it ideal for building up large structures, such as airframes, or replacement parts, such as turbine blades that are then machined.
Wire Directed Energy Deposition.
Wire Directed Energy Deposition, also known as Wire Arc Additive Manufacturing (WAAM), is 3D printing that uses energy in the form of plasma or wire arc to melt metal in wire form where it’s deposited layer on top of layer by a robotic arm onto a surface, such as a multi-axis turntable, to form a shape.
This method is chosen over similar technologies involving lasers or electron beams because it doesn’t require a sealed chamber and it can use the same metals (sometimes the exact same material) as traditional welding.
Electric direct energy deposition is considered the most cost-effective option among the DED technologies because it can use existing arc-welding robots and power supplies, so the barrier to entry is relatively low.
Unlike welding, this technology uses complex software to control a menu of variables in the process, including the thermal management and toolpath of the robotic arm.
There are no support structures to remove, and finished parts are typically CNC machined to tight tolerances if necessary or surface polished. Often, printed parts receive a heat treatment to relieve any residual stresses.
Cold Spray.
Cold spray is a DED 3D printing technology that sprays metal powders at supersonic speeds to bond them without melting them, which produces almost no thermal stress that can produce hot-cracking or other common problems that can affect melt-based technologies.
Since the early 2000s, it’s been used as a coating process, but more recently, several companies have adapted cold spray for additive manufacturing because it can layer metal in exact geometries up to several centimeters at about 50 to 100 times higher speed than typical metal 3D printers, and there’s no need for inert gases or vacuum chambers.
Like all DED processes, cold spray doesn’t produce prints of great surface quality or detail, but that’s not always required and parts can be used right off of the print bed.
Molten Directed Energy Deposition.
Molten Direct Energy Deposition is a 3D printing process that uses heat to melt (or near melt) metal, usually aluminum, then deposit it on a build plate layer by layer to form a 3D object.
This technology differs from metal extrusion 3D printing in that the extrusion versions use a metal feedstock with a bit of polymer inside to make the metal extrudable.
The polymer is then removed in the heat treatment stage. Molten DED, on the other hand, uses a pure metal.
One could also liken molten or liquid DED to material jetting, but instead of an array of nozzles depositing droplets, the liquid metal is generally streamed from a nozzle.
The benefit of this approach is that there’s no hazardous metal powder to work with and the finished prints do not require any post-processing.
It also uses less energy than other DED processes and there the potential to use recycled metal directly as feedstock instead of wire or highly processed metal powders.
#6. Binder Jetting.
Binder jet 3D printing is widely regarded as the fastest additive manufacturing method for production-volume output of highly dense and functional precision parts.
The binder jetting process uses two materials; a powder-based material and a binder. The binder acts as an adhesive between powder layers.
The binder is usually in liquid form and the build material in powder form. A print head moves horizontally along the x and y axes of the machine and deposits alternating layers of the build material and the binding material.
After each layer, the object being printed is lowered on its build platform.
Due to the method of binding, the material characteristics are not always suitable for structural parts and despite the relative speed of printing, additional post processing can add significant time to the overall process.
As with other powder-based manufacturing methods, the object being printed is self-supported within the powder bed and is removed from the unbound powder once completed.
The technology is often referred to as 3DP technology and is copyrighted under this name.
Metal Binder Jetting.
Metal binder jetting is undergoing a renaissance. Over the last decade, many new companies have entered a competition mode, each with its own take on this technology.
In metal binder jetting, a liquid binder is selectively applied to join powder particles, layer by layer.
The process begins by spreading a thin layer of powder, with printheads strategically depositing droplets of binder into the powder bed. The printing plate then lowers and another layer of powder is spread.
The process repeats until the part is complete, with unused powder (around 95%) recycled.
With metal binder jetting, parts that have just been printed remain in a fragile green state and will require subsequent post-processing, such as sintering and infiltration, to strengthen the part.
In addition to metals, binder jetting can work with a range of other materials, like sand and ceramics.
Plastic Binder Jetting (MJF, HSS, SAF).
Plastic Binder Jetting is a very similar process to metal binder jetting since it involves a powder and a liquid binding agent.
Polymer binder jetting begins with a polymer powder (usually a type of nylon) spread across a build platform in a thin layer.
Then inkjet heads dispense a binder-like glue precisely where the polymer should be joined on each layer.
In some methods, there’s a heating unit attached to the inkjet head or on a separate carriage that fuses the parts of the layer that receive the fluid.
The methods that include this heating step create stronger parts than the ones that don’t because the polymer powder is essentially melted together rather than only glued together.
Binder jetting with heat, such as Multi Jet Fusion, High Speed Sintering, and Selective Absorption Fusion, is comparable to the technology that uses lasers to melt polymer powder called selective laser sintering but is faster, offers a smoother surface finish and you’re able to reuse more of the powder left over from a printer run.
This is a versatile technology that has found use in several industries, from automotive to healthcare to consumer products.
Binder jetting variations without heat can be infilled with another material to boost strength.
These cold binder jetting processes are also the ones that include colored inks and can produce multi-color parts used in medical modeling and product prototypes.
Once printed, plastic parts are removed from their powder bed, cleaned, and can be used without any further processing.
Sand Binder Jetting.
Sand binder jetting is arguably not a distinct technology from plastic binder jetting but the printers and applications are different enough to earn a separate entry here.
In fact, producing large sand-casting molds, models, and cores is one of the most common uses for binder jetting technology.
The low cost and speed of the process make it an excellent solution for foundries. Elaborate pattern designs that would be very difficult or impossible to produce using traditional techniques can be printed in a matter of hours.
The future of industrial development continues to place high demands on foundries and suppliers. Sand 3D printing is at the beginning of its potential.
Sand binder jetting 3D printers product parts from sandstone or gypsum. After printing, the cores and molds are removed from the build area and cleaned to remove any loose sand.
The molds are typically immediately ready for casting. After casting, the mold is broken apart, and the final metal component is removed.
#7. Sheet Lamination.
Sheet lamination is technically a form of 3D printing, although it differs dramatically from the technologies above.
It functions by stacking and laminating sheets of very thin material together to produce a 3D object or a stack that’s then cut mechanically or with lasers to form the final shape.
Material layers can be fused together using a variety of methods, including heat and sound, depending on the material in question. Materials range from papers or polymers to metals.
When parts are laminated, a laser then cuts or machins the desired shape, which leads to more waste than in other 3D printing technologies.
Manufacturers use sheet lamination to produce cost-effective, non-functional prototypes at a relatively high speed, it’s also a promising electric battery technology and can be used to produce composite items, as the materials used can be swapped around during the printing process.
Laminated Additive Manufacturing.
Laminating is a 3D printing technology where sheets of material are layered on top of each other and bonded together using glue then a knife (or laser, or CNC router) is used to cut the layered object into the correct shape.
The technology is less common today because the cost of other 3D printing technology has fallen while the size, speed, and ease-of-use of 3D printers in other technology categories has dramatically increased.