• Powder Bed Fusion is a process where some kind of a thermal energy source which will selectively induce fusion between powder particles inside a build area to create a solid object.

• There are many devices which also provide a mechanism for applying and smoothing the powder simultaneously to the object being fabricated on the print platform, so that the final item is encased and supported in unused powder.

• Creating an object with this technology and polymer powder is called as "Selective Laser Sintering" (SLS). These types of technologies are becoming common and cheaper now-a-days.

• In this, a bin of polymer powder is heated to a desired temperature just below the polymer's melting point. Then, a re-coating blade or wiper deposits a very thin layer of the powdered material - typically 0.1 mm think - onto a build platform. After that a high powered Carbon Dioxide laser beam begins to scan the previously layered powder surface. The laser will selectively sinter the powder and solidify a cross-section of the object. Just like Stereolithography process (SLA), a laser is focused on the correct location by a pair of galvanometers, which are actually mirrors positioned on the X-axis and Y-axis.

• When the entire cross-section is scanned, the build platform moves down one layer thickness in height. The re-coating blade deposits a fresh layer of powder material on the top of the recently scanned layer, and then the laser will sinter the next cross-section of the object onto the previously solidified cross-section.

• These steps are repeated until all objects are entirely manufactured. The powder which hasn't been sintered remains in place to support the object that has, which eliminates the need for support structures.

• Since finished part density depends upon the peak laser power, rather than the laser duration for sintering, an SLS 3D Printer is typically uses a pulsed laser, meaning the laser is not classified as continuous wave, so that the optical power appears in pulses of some duration.

• Major disadvantage with SLS that it is 'impossible' to fabricate a hollow but fully enclosed element. This is because the un-sintered powder within the element could not be drained.

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• Materials: Thermoplastic Powder (Nylon 6, Nylon 11, Nylon 12)

• Dimensional Accuracy: ±0.3%

• Common Applications: Functional Parts, Complex Ducting, Low run part production

• Strengths: Functional Parts, Excellent Mechanical Properties, Complex Geometries

• Weaknesses: Longer lead time, Higher cost than FFF for functional applications