Selective sintering laser ( SLS ) is an additive manufacturing technique (AM) that uses lasers as a resource for sintered powder (usually nylon/polyamide), laser-targeting automatically at point -spots in the space defined by the 3D model, binding together the material to create a solid structure. This is similar to direct metal sintering lasers (DMLS); both are examples of the same concept but different in technical terms. Selective laser melting (SLM) uses comparable concepts, but in SLM the material is completely melted rather than sintered, allowing different properties (crystal structure, porosity, etc.). SLS (as well as other mentioned AM techniques) is a relatively new technology that is so far primarily used for rapid prototyping and for the production of low-volume component parts. The role of production grows as commercialization of AM technology increases.
Video Selective laser sintering
Histori
Selective laser sintering (SLS) was developed and patented by Dr. Carl Deckard and academic adviser, Dr. Joe Beaman at the University of Texas at Austin in the mid-1980s, under the DARPA sponsorship. Deckard and Beaman are involved in the start up of the DTM company, established to design and build SLS engines. In 2001, 3D Systems, the largest competitor for DTM and SLS tec hnology, acquired DTM. The latest patent on SLS Deckard technology was issued January 28, 1997 and ends January 28, 2014.
The same process was patented without being commercialized by R. F. Housholder in 1979.
Because SLS requires the use of high-power lasers, they are often too expensive, not to mention too dangerous, for home use. The cost and potential hazards of SLS printing mean that the home market for SLS printing is not as big as the market for other additive manufacturing technologies, such as Fused Deposition Modeling (FDM). Nevertheless, there are some individuals and companies focused on bringing this technology to individual consumers. One such person is Andreas Bastian, an engineering student from Swarthmore College, who recently developed a relatively inexpensive SLS printer capable of creating objects of wax or carbon. Another option for SLS printing at home is the Focus SLS printer. Barry Mayers patented the design in early 2000 under the trademark CB Company Limited.
Maps Selective laser sintering
Technology
Additive coating manufacturing technology, SLS involves the use of high-power lasers (eg, carbon dioxide lasers) to blend small particles of plastic, metal, ceramic, or glass powder into a mass that has the desired three-dimensional shape. The laser selectively unifies the powder material by scanning the cross section resulting from the 3-D digital description of the part (eg from the CAD file or scanning data) on the powder bed surface. After each cross-section is scanned, the bed bed is reduced by a single layer of thickness, a new layer of material is applied on top, and the process is repeated until the piece is finished.
Because the density of the finished part depends on the power of the peak laser, rather than the duration of the laser, the SLS machine usually uses pulsed lasers. The SLS machine preheats bulk powder material in the powder bed below its melting point, to allow the laser to raise the temperature of the selected area to the point of melting.
In contrast to some other additive manufacturing processes, such as stereolithography (SLA) and fused deposition modeling (FDM), most often requiring a special support structure to create a protruding design, the SLS does not require a separate feeder for supporting material because the part being built is surrounded by a powder which is untouched at all times, this allows for the construction of previously impossible geometry. Also, since the engine room is always filled with powder material, fabrication of some parts has a much lower impact on the overall difficulty and price of the design because through a technique known as 'Nesting' some parts can be positioned to fit the limits of the machine. One aspect of the design that has to be observed however is that with the SLS it is 'not possible' to fabricate hollow elements but is completely closed. This is because the unprocessed powders in the element can not be dried.
Because patents are out of date, affordable home printers are possible, but the heating process is still a constraint, with power consumption up to 5 kW and the temperature should be controlled in 2 Ã, Â ° C for the three initial warm-up stages, melting and storing before disposal. [1]
Materials and apps
Some SLS machines use single component powders, such as direct metal laser sintering. Powders are generally produced by grinding the ball. However, most SLS machines use two-component powders, usually powder-coated or powdered mixtures. In a single component powder, the laser simply melts the outer surface of the particle (surface smelting), combining a solid core that does not melt into each other and into the previous layer.
Compared to other additive-making methods, SLS can produce components of various types of commercially available powder powder. These include polymers such as nylon (neat, filled glasses, or with other fillers) or polystyrene, metals including steel, titanium, mixed mixtures, and composites and green sands. Physical processes can be full melt, partial melting, or liquid-phase sintering. Depending on the material, up to 100% density can be achieved with material properties comparable to those from conventional manufacturing methods. In many cases, a large number of parts can be packaged in a bed bed, which allows very high productivity.
SLS technology is widely used worldwide for its ability to easily create highly complex geometries directly from digital CAD data. Although this started as a way to build prototype parts early in the design cycle, it is increasingly being used in limited run manufacturing to produce the final parts of use. One SLS application that is less desirable and growing rapidly is its use in art.
Because SLS can produce components made of various materials (plastic, glass, ceramic, or metal), SLS is rapidly becoming a popular process for creating prototypes, and even end products. SLS has increasingly been used in industry in situations where a small number of high-quality components are required, such as in the aerospace industry, where SLS is used more often to create prototypes for aircraft. Aircraft are often built in small quantities and have remained in operation for decades, resulting in physical molds for spare parts to be ineffective, so SLS has become an excellent solution.
Advantages vs. loss
Advantages
The distinct advantage of the SLS process is that because it is entirely self-contained, it allows for parts to be built in other parts of the process called nesting - with very complicated geometries that can not be built any other way.
Parts have high strength and stiffness
Good chemical resistance
Various possible finishing (eg, metallization, stove enameling, vibration milling, tub dyeing, binding, powder, coating, flocking)
Bio compatible according to EN ISO 10993-1 and USP/level VI/121 Â ° C
Complex parts with interior components, ducts, can be constructed without trapping material inside and changing the surface of removal support.
The fastest additive manufacturing process for printing functional, durable, prototype or end-user parts.
A wide range of materials and characteristics Strength, durability, and functionality, SLS offers Nylon based materials as a solution depending on the application.
Due to its excellent mechanical properties, the material is often used to replace typical plastic injection molding.
Losses
The part that is printed SLS has a porous surface. This can be sealed by applying layers like cyanoacrylate.
See also
- 3D Printing
- Desktop creation
- Digital assembler
- Direct digital creation
- Fab Lab
- Merged deposition modeling (FDM)
- Instant manufacturing, also known as direct manufacturing or manufacturing on demand
- Quick creation
- Quick prototyping
- RepRap Project
- Solid fabrication of unique shape
- Stereolithography (SLA)
- Von Neumann universal constructor
References
External links
- DMLS - RIWAYAT DEVELOPMENT AND ART STATE
- Selective Laser Sintering, Birth Industry
Source of the article : Wikipedia
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