Binder jet 3D printing, known variously as "Powder bed and inkjet" and "drop-on-powder" printing, is a rapid prototyping and additive manufacturing technology for making objects described by digital data such as a CAD file. Binder jetting is one of the seven categories of additive manufacturing processes according to ASTM and ISO. [1]
This technology was first developed at the Massachusetts Institute of Technology and patented in 1993. In 1996, the ExOne Company was granted an exclusive field-of-use patent for the technology, [2] while Z Corporation, which was later acquired by 3D Systems, [3] obtained a non-exclusive patent for use of the technology for metal casting purposes. [4] The term "Three-Dimensional Printing" was trademarked by the research group at MIT, along with the abbreviation 3DP. [5] [6] As a result, the term "3D printing" originally referred uniquely to the binder jet printing process prior to gaining wider acceptance as a term referring to all additive manufacturing processes.
As in many other additive manufacturing processes the part to be printed is built up from many thin cross sections of the 3D model. An inkjet print head moves across a bed of powder, selectively depositing a liquid binding material. A thin layer of powder is spread across the completed section and the process is repeated with each layer adhering to the last.
When the model is complete, unbound powder is automatically and/or manually removed in a process called "de-powdering" and may be reused to some extent. [7]
The de-powdered part could optionally be subjected to various infiltrants or other treatments to produce properties desired in the final part.
In the original implementations, starch and gypsum plaster fill the powder bed, the liquid "binder" being mostly water to activate the plaster. The binder also includes dyes (for color printing), and additives to adjust viscosity, surface tension, and boiling point to match print head specifications. The resulting plaster parts typically lack "green strength" and require infiltration by melted wax, cyanoacrylate glue, epoxy, etc. before regular handling.
While not necessarily employing conventional inkjet technology, various other powder-binder combinations may be deployed to form objects by chemical or mechanical means. The resulting parts may then be subjected to different post-processing regimes, such as infiltration or bakeout. This may be done, for example, to eliminate the mechanical binder (e.g., by burning) and consolidate the core material (e.g., by melting), or to form a composite material blending the properties of powder and binder. Depending on the material, full color printing may or may not be an option. As of 2014, inventors and manufacturers have developed systems for forming objects from sand and calcium carbonate (forming a synthetic marble), acrylic powder and cyanoacrylate, ceramic powder and a liquid binder, sugar and water (for making candies), etc. One of the first commercially available products that incorporated the use of Graphene, was a powdered composite used in powder bed inkjet head 3D printing. [8]
3D printing technology has a limited potential to vary material properties in a single build, but is generally limited by the use of a common core material. In the original Z Corporation systems, cross-sections are typically printed with solid outlines (forming a solid shell) and a lower-density interior pattern to speed printing and ensure dimensional stability as the part cures.
In addition to volumetric color by use of multiple print heads and colored binder, the 3D printing process is generally faster than other additive manufacturing technologies such as fused deposition modeling material jetting which require 100% of build and support material to be deposited at the desired resolution. In 3D printing, the bulk of each printed layer, regardless of complexity, is deposited by the same, rapid spreading process. [9]
As with other powder-bed technologies, support structures are generally not required because loose powder supports overhanging features and stacked or suspended objects. The elimination of printed support structures can reduce build time and material use and simplify both equipment and post-processing. However, de-powdering itself can be a delicate, messy, and time-consuming task. Some machines therefore automate de-powdering and powder recycling to what extent feasible. Since the entire build volume is filled with powder, as with stereolithography, means to evacuate a hollow part must be accommodated in the design.
Like other powder-bed processes, surface finish and accuracy, object density, and—depending on the material and process—part strength may be inferior to technologies such as stereolithography (SLA) or selective laser sintering (SLS). Although "stair-stepping" and asymmetrical dimensional properties are features of 3D printing as most other layered manufacturing processes, 3D printing materials are generally consolidated in such a way that minimizes the difference between vertical and in-plane resolution. The process also lends itself to rasterization of layers at target resolutions, a fast process that can accommodate intersecting solids and other data artifacts.
Powder bed and inkjet 3D printers typically range in price from $50,000 to $2,000,000 [ citation needed ] however there is a hobbyist DIY kit selling from $800 to convert a consumer FDM printer to powder/inkjet printer.
Parts printed using the binder jetting process are inherently porous and have an unfinished surface, as unlike powder bed fusion the powders are not physically melted and are joined by a binding agent. While the usage of a binding agent allows for high melting temperature (e.g. ceramic) and heat-sensitive (e.g. polymer) materials to be powdered and used for additive manufacturing, binder jetting parts require additional post-processing that can require more time than it takes to print the part, such as curing, sintering, and additional finishing . [10]
Binder jetting is particularly prone to the phenomena of powder bed depletion, which occurs when the binder is dropped onto the surface of the powder bed. This issue is particularly prevalent in binder jetting, as unlike traditional additive manufacturing processes (which utilize high heat to melt and fuse powders together), the "jet" of binder that is dropped onto the bed can cause large agglomerates of semi-bonded powder to be ejected from the surface, leaving behind subsurface depletion zones (for 30 μm SS316 powder, a depletion zone depth of 56±12μm was observed). The growth of depletion zones as subsequent layers of powder are deposited printed can have major ramifications on the quality of parts printed with binder jetting. Ejected agglomerates land on other regions of the bed, causing the surface of the bed to become less even, the dimensions of the final part to be warped and inaccurate, and large subsurface pores to form. Residual defects and stress may also be present throughout, which reduce the strength of the already weaker part (due to the inherent porosity of the binder jetted part) . [11]
These factors limit the usage of binder jetting for high-performance applications, such as for aerospace, as binder jetted parts are generally weaker than those printed with powder bed fusion processes. However, binder jetting is perfect for rapid prototyping and production of low-cost metal parts . [12]
Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensive consumer models to expensive professional machines. By 2019, laser printers outsold inkjet printers by nearly a 2:1 ratio, 9.6% vs 5.1%.
Selective laser sintering (SLS) is an additive manufacturing (AM) technique that uses a laser as the power source to sinter powdered material, aiming the laser automatically at points in space defined by a 3D model, binding the material together to create a solid structure. It is similar to selective laser melting; the two are instantiations of the same concept but differ in technical details. SLS is a relatively new technology that so far has mainly been used for rapid prototyping and for low-volume production of component parts. Production roles are expanding as the commercialization of AM technology improves.
3D printing, or additive manufacturing, is the construction of a three-dimensional object from a CAD model or a digital 3D model. The term "3D printing" can refer to a variety of processes in which material is deposited, joined or solidified under computer control to create a three-dimensional object, with material being added together, typically layer by layer.
3D Systems, headquartered in Rock Hill, South Carolina, is a company that engineers, manufactures and sells 3D printers, 3D printing materials, 3D scanners, and offers a 3D printing service. Chuck Hull, the CTO and former president, pioneered stereolithography and obtained a patent for the technology in 1986. The company creates product concept models, precision and functional prototypes, master patterns for tooling, as well as production parts for direct digital manufacturing. It uses proprietary processes to fabricate physical objects using input from computer-aided design and manufacturing software, or 3D scanning and 3D sculpting devices.
Solid ink is a type of ink used in printing. Solid ink is a waxy resin-based polymer that must be melted prior to usage, unlike conventional liquid inks. The technology is used most in graphics and large format printing environments, where color vividness and cost efficiency are important.
Electron-beam additive manufacturing, or electron-beam melting (EBM) is a type of additive manufacturing, or 3D printing, for metal parts. The raw material is placed under a vacuum and fused together from heating by an electron beam. This technique is distinct from selective laser sintering as the raw material fuses having completely melted.
Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data. Construction of the part or assembly is usually done using 3D printing or "additive layer manufacturing" technology.
Digital modeling and fabrication is a design and production process that combines 3D modeling or computing-aided design (CAD) with additive and subtractive manufacturing. Additive manufacturing is also known as 3D printing, while subtractive manufacturing may also be referred to as machining, and many other technologies can be exploited to physically produce the designed objects.
Z Corporation was founded in December 1994 by Marina Hatsopoulos, Walter Bornhorst, James Bredt and Tim Anderson, based on a technology developed at MIT under the direction of Professor Ely Sachs. The Company was sold to Contex Holding in August 2005, and was ultimately acquired by 3D Systems on January 3, 2012.
Selective laser melting (SLM) is one of many proprietary names for a metal additive manufacturing technology that uses a bed of powder with a source of heat to create metal parts. Also known as direct metal laser melting (DMLM), the ASTM standard term is powder bed fusion (PBF). PBF is a rapid prototyping, 3D printing, or additive manufacturing (AM) technique designed to use a high power-density laser to melt and fuse metallic powders together.
Robocasting is an additive manufacturing technique analogous to Direct Ink Writing and other extrusion-based 3D-printing techniques in which a filament of a paste-like material is extruded from a small nozzle while the nozzle is moved across a platform. The object is thus built by printing the required shape layer by layer. The technique was first developed in the United States in 1996 as a method to allow geometrically complex ceramic green bodies to be produced by additive manufacturing. In robocasting, a 3D CAD model is divided up into layers in a similar manner to other additive manufacturing techniques. The material is then extruded through a small nozzle as the nozzle's position is controlled, drawing out the shape of each layer of the CAD model. The material exits the nozzle in a liquid-like state but retains its shape immediately, exploiting the rheological property of shear thinning. It is distinct from fused deposition modelling as it does not rely on the solidification or drying to retain its shape after extrusion.
Fused filament fabrication (FFF), also known as fused deposition modeling, or called filament freeform fabrication, is a 3D printing process that uses a continuous filament of a thermoplastic material. Filament is fed from a large spool through a moving, heated printer extruder head, and is deposited on the growing work. The print head is moved under computer control to define the printed shape. Usually the head moves in two dimensions to deposit one horizontal plane, or layer, at a time; the work or the print head is then moved vertically by a small amount to begin a new layer. The speed of the extruder head may also be controlled to stop and start deposition and form an interrupted plane without stringing or dribbling between sections. "Fused filament fabrication" was coined by the members of the RepRap project to give a phrase that would be legally unconstrained in its use, under the mistaken belief that a trademark protected the term "fused deposition modeling".
voxeljet AG, which is based in Friedberg (Bayern) near Augsburg (Germany), is a manufacturer of industrial 3D printing systems. The company has been listed on the Nasdaq since 2020, and previously listed on the New York Stock Exchange since its IPO in 2013. Besides the development and distribution of printing systems, voxeljet AG also operates service centers for the on-demand manufacture of molds and models for metal casting in Germany and abroad. These products are manufactured with the help of a generative production method based on 3D CAD data.
Inkjet technology originally was invented for depositing aqueous inks on paper in 'selective' positions based on the ink properties only. Inkjet nozzles and inks were designed together and the inkjet performance was based on a design. It was used as a data recorder in the early 1950s, later in the 1950s co-solvent-based inks in the publishing industry were seen for text and images, then solvent-based inks appeared in industrial marking on specialized surfaces and in the1990's phase change or hot-melt ink has become a popular with images and digital fabrication of electronic and mechanical devices, especially jewelry. Although the terms "jetting", "inkjet technology" and "inkjet printing", are commonly used interchangeably, inkjet printing usually refers to the publishing industry, used for printing graphical content, while industrial jetting usually refers to general purpose fabrication via material particle deposition.
Rule based DFM analysis for direct metal laser sintering. Direct metal laser sintering (DMLS) is one type of additive manufacturing process that allows layer by layer printing of metal parts having complex geometries directly from 3D CAD data. It uses a high-energy laser to sinter powdered metal under computer control, binding the material together to create a solid structure. DMLS is a net shape process and allows the creation of highly complex and customized parts with no extra cost incurred for its complexity.
3D metal moulding, also referred to as metal injection moulding or (MIM), is used to manufacture components with complex geometries. The process uses a mixture of metal powders and polymer binders – also known as "feedstock" – which are then injection-moulded.
A variety of processes, equipment, and materials are used in the production of a three-dimensional object via additive manufacturing. 3D printing is also known as additive manufacturing, therefore the numerous available 3D printing process tend to be additive in nature with a few key differences in the technologies and the materials used in this process.
Cold spray additive manufacturing (CSAM) is a particular application of cold spraying, able to fabricate freestanding parts or to build features on existing components. During the process, fine powder particles are accelerated in a high-velocity compressed gas stream, and upon the impact on a substrate or backing plate, deform and bond together creating a layer. Moving the nozzle over a substrate repeatedly, a deposit is building up layer-by-layer, to form a part or component. If an industrial robot or computer controlled manipulator controls the spray gun movements, complex shapes can be created. To achieve 3D shape, there are two different approaches. First to fix the substrate and move the cold spray gun/nozzle using a robotic arm, the second one is to move the substrate with a robotic arm, and keep the spray-gun nozzle fixed. There is also a possibility to combine these two approaches either using two robotic arms or other manipulators. The process always requires a substrate and uses only powder as raw material.
Multi-material 3D printing is the additive manufacturing procedure of using multiple materials at the same time to fabricate an object. Similar to single material additive manufacturing it can be realised through methods such as FFF, SLA and Inkjet 3D printing. By expanding the design space to different materials, it establishes the possibilities of creating 3D printed objects of different color or with different material properties like elasticity or solubility. The first multi-material 3D printer Fab@Home became publicly available in 2006. The concept was quickly adopted by the industry followed by many consumer ready multi-material 3D printers.
3D food printing is the process of manufacturing food products using a variety of additive manufacturing techniques. Most commonly, food grade syringes hold the printing material, which is then deposited through a food grade nozzle layer by layer. The most advanced 3D food printers have pre-loaded recipes on board and also allow the user to remotely design their food on their computers, phones or some IoT device. The food can be customized in shape, color, texture, flavor or nutrition, which makes it very useful in various fields such as space exploration and healthcare.