Stereolithography (SLA), also known as photolithography, light-curing three-dimensional modeling, is a 3D printing technology used to create models, prototypes, patterns, etc. It uses the photopolymerization method to link small molecules to form polymers by light irradiation. These polymers form a solidified three-dimensional 3D object.

An SLA printer adopts mirrors that known as galvanometers or galvos, with one positioned on the X-axis and another on the Y-axis. These galvos rapidly aim a laser beam across a vat of resin, selectively curing and solidifying a cross-section of the object inside this building area, building it up layer by layer.Most SLA printers use a solid-state laser to cure parts. SLA printing needs common material is photopolymer resins.   SLA printing dimensional accuracy can be upto   ±0.5%, so comparing to traditional injection molding manufacturing, its strength is castable,transparent, biocompatable, fast and has a wide application in jewelry casting,dental,prototyping, games models, and others industrial applications.

As one of   three common forms of vat polymerization(SLA, MSLA and DLP), digital light processing (DLP) uses a digital light projector to flash a single image of each layer all at once (or multiple flashes for larger parts).

Just like SLA counterparts, DLP 3D printers are built around a resin tank with transparent bottom and a build platform that descends into a resin tank to create parts upside down, layer by layer.The light is reflected on a digital micromirror device, a dynamic mask consisting of microscopic-size mirrors laid out in a matrix on a semiconductor chip. Rapidly toggling these tiny mirrors between lens(es) that direct the light towards the bottom of the tank or a heat sink defines the coordinates where the liquid resin cures within the given layer.

Masked Stereolithography (MSLA) uses an LED array as its light source, shining UV light through an LCD screen displaying a single layer slice as a mask — hence the name.Like DLP, the LCD photomask is digitally displayed and composed of square pixels. The pixel size of the LCD photomask defines the granularity of a print. Thus, the XY accuracy is fixed and does not depend on how well you can zoom/scale the lens, as is the case with DLP. Another difference between DLP-based printers and MSLA technology is that the latter utilizes an array of hundreds of individual emitters rather than a single-point emitter light source like a laser diode or DLP bulb.

Similar to DLP, MSLA can, under certain conditions, achieve faster print times compared to SLA. That’s because an entire layer is exposed at once rather than tracing the cross-sectional area with the point of a laser.Due to the low cost of LCD units, MSLA has become the go-to technology for the budget desktop resin printer segment.

Selective laser sintering   (SLS) is an additive manufacturing technique that uses a laser as a power source to sinter powdered materials, automatically aiming the laser at a point in a space defined by a 3D model, bonding the materials together to form a strong structure. It is similar to selective laser melting; both are instances of the same concept, but differ in technical details. SLS is a relatively new technology, and so far it has mostly been used for rapid prototyping and low-volume production of parts.

SLS printing involves the use of a high power laser (for instance,a carbon dioxide laser) to fuse small particles of metal, ceramic, or glass powders into a mass that has a desired three-dimensional shape. The laser selectively fuses powdered material by scanning cross-sections generated from a 3-D digital description of the part (for example from a CAD file or scan data) on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed.

Multi Jet Fusion (MJF) is a 3D printing process that speedily produces accurate and finely detailed complex parts with powdered thermoplastics. Using an inkjet array, MJF works by depositing fusing and detailing agents in a bed of powder material, then fusing them into a solid layer. The printer distributes more powder on top of the bed, and the process repeats layer by layer.

Multi Jet Fusion uses a fine-grained materials that allows for ultra-thin layers of 80 microns. This leads to parts with high density and low porosity, compared to parts produced with Laser Sintering. It also leads to an exceptionally smooth surface straight out of the printer, and functional parts need minimal post-production finishing. That means short lead times, ideal for functional prototypes and small series of end-parts.For industrial applications. It’s commonly used to manufacture functional prototypes and end-use parts, parts that need consistent isotropic mechanical properties, and geometries that are organic and complex.

PolyJet printing is an industrial 3D printing process that builds multi-material prototypes with flexible features and complex parts with intricate geometries in as fast as 1 day. A range of hardnesses (durometers) are available, which work well for components with elastomeric features like gaskets, seals, and housings.

The PolyJet process begins by spraying small droplets of liquid photopolymers in layers that are instantly UV cured. Voxels (three-dimensional pixels) are strategically placed during the build, which allow for the combination of both flexible and rigid photopolymers know as digital materials. Each voxel has a vertical thickness equal to the layer thickness of 30 microns. The fine layers of digital materials accumulate on the build platform to create accurate 3D-printed parts.

Direct Metal Laser Sintering (DMLS) is a direct metal laser melting (DMLM) or laser powder bed fusion (LPBF) technology that accurately forms complex geometries not possible with other metal manufacturing methods.

DMLS uses a precise, high-wattage laser to micro-weld powdered metals and alloys to form fully functional metal components from your CAD model.DMLS parts are made with powdered materials like aluminum, stainless steel and titanium, as well as niche alloys like MONEL® K500 and Nickel Alloy 718.

EBM printing technology uses an electron beam produced by an electron gun. The latter extracts the electrons from a tungsten filament under vacuum and projects them in an accelerated way on the layer of metallic powder deposited on the building plate of the 3D printer. These electrons will then be able to selectively fuse the powder and thus produce the part.

EBM technology is mainly used in aeronautics and medical applications, particularly for implant design. Titanium alloys are particularly interesting because of their biocompatible properties and mechanical properties, they can offer lightness and strength. The technology is widely used to design turbine blades, for example, or engine parts. Electron Beam Melting technology will create parts faster than LPBF technology, but the process is less accurate and the finish will be of lower quality because the powder is more granular.