3D Printing

Stereolithography 3D printer showing 3D object emerging from vat of resin

3D printing, also called additive manufacturing, is a process for making a three-dimensional object from a digital model by successively fabricating material layer-by-layer in an additive manner. First, a virtual 3D representation of the object is rendered using computer-aided design (CAD). Then, the model is ‘sliced’ into a series of horizontal layers to convert the design into an STL (standard tessellation language) file that is readable for the 3D printer. This data is then transferred to the printer, and the printer settings are defined. The final object is produced one layer at a time, with each layer bonding and building on the previous one.

Due to the ability to produce very complex shapes and structures with high precision and repeatability from a diverse range of materials, 3D printing is used for a broad range of applications in aerospace, automotive, construction, fashion, food, jewelry, manufacturing, and medical sectors. There are numerous techniques to 3D print objects with different mechanical, thermal, and chemical properties from materials in molten, liquid, or powder states.

Among the popular 3D printing technologies are:​


Related Technical Articles


Fused Deposition Modeling (FDM)

Fused deposition modeling (FDM), also called fused filament fabrication (FFF) or material extrusion, is the most common and inexpensive 3D printing technology. A spool of thermoplastic filament (e.g., PLA, ABS) is heated to its melting point and extruded through a nozzle onto a platform, where the molten material cools and solidifies. This technology is used in injection molding and modern plastic manufacturing for ready-to-use products.

Vat Polymerization

Vat polymerization uses photopolymerization to cure and solidify liquid polymer resin. Stereolithography (SL) was the first type of 3D printing developed and commercialized using this method. An SL printer uses mirrors positioned at the X-Y axes to direct a laser beam across a vat of resin to create a cross-section of the object. Digital light processing (DLP) uses a projector with an LCD screen or UV light source to flash light, creating each layer. This type of resin-based 3D printing is fast because an entire layer is exposed all at once. Masked stereolithography (MLA) uses an array of LEDs to shine UV light through a liquid crystal display (LCD) photomask.

Fused Deposition Modeling(FDM)

Fused deposition modeling (FDM), also called fused filament fabrication (FFF) or material extrusion, is the most common and inexpensive 3D printing technology. A spool of thermoplastic filament (e.g., PLA, ABS) is heated to its melting point and extruded through a nozzle onto a platform, where the molten material cools and solidifies. This technology is used in injection molding and modern plastic manufacturing for ready-to-use products.

Powder Bed Fusion

Powder bed fusion selectively cures polymer or metal powders with a thermal energy source to create a solid plastic or metal object. First, the powder is heated to a temperature just below its melting point. Then, a roller distributes a very thin layer of powder over the surface of the building bed before a laser passes over the layer to fuse it. Once a layer is completed, the powder bed sinks incrementally to form the next layer. Selective laser sintering (SLS) successively sinters polymer powder with a laser. Selective laser melting (SLM) involves fully melting metal powder instead of sintering it. Other forms of metal powder bed fusion include direct metal laser sintering (DMLS) and electron beam melting (EBM).

Jetting

Material jetting uses inkjet printer technology to add tiny droplets of photopolymers or wax onto a build plate. An ultraviolet (UV) light simultaneously cures the layers as they are printed. Material jetting (MJ) deposits material in a rapid, line-wise fashion, rather than point-wise. Therefore, multiple objects can be fabricated in a single line. Moreover, this method allows different materials to be printed in the same object. Drop-on-demand (DOD) 3D printing technology uses a set of two inkjets to deposit both the final object material and dissolvable support material simultaneously.






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