Selective Laser Sintering

A. Process

Selective Laser Sintering is a 3D printing process that uses a high powered pulsating laser to sinter powdered material layer by layer to form solid 3D prototype parts. The powdered material is preheated to a temperature slightly below melting point to make it easier for the laser to melt the powder together into a solid 3D prototype. As with any form of 3D printing, this process begins with a CAD file, which is then converted by the software into hundreds of horizontal layers depending on its size.

Once the CAD data is sent to the 3D printer, the laser creates the first layer by selectively fusing, or sintering, the material by scanning the cross sections onto the surface of the bed of powder. Once the first cross section is complete, the powder bed is lowered by the thickness of one layer, a new layer of powder is applied above, and the process repeats until the entire part is complete. Once the prototype is fully formed, it is left to cool before being removed from the bed of powder. The last step in the process involves abrasive blasting, an operation where a stream of abrasive material is forced against the object under high pressure to smooth a rough surface.

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B. Materials

1. PA
This white prototype material has excellent surface resolution and is very easy to process. It produces accurate, durable, and repeatable end-use prototype parts without tooling as demanded by the manufacturers.
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2. GF
This gray prototype material has excellent mechanical stiffness and is very easy to process. It is dimensionally stable and has good load bearing capacity at elevated temperatures.
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3. EX
This prototype material has excellent toughness and is very easy to process. It possesses excellent impact resistance and repeatable mechanical properties. Prototypes made from this material can be tested in “real life” environments.
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C. Design Guidelines

1. Maximum build size
Maximum size for prototype parts that can be built using this technology is 21.6 in. x 21.6 in. x 29.5 in.

2. Tolerances
Tolerances of ±0.010 in. can be typically achieved on prototypes that are well designed.

3. Minimum feature size
Minimum feature size that can be achieved is 0.020 in. for prototypes that are well designed.

Sharp edges or points – Current machines cannot produce prototype parts with sharp edges or points as minimum feature size is limited to 0.020 in.

Living Hinges – Most prototype materials work well with living hinges. Urethane casting process can be also be used instead if this feature is crucial.

Text or Logos – Current 3D printers cannot produce prototypes with text or logos which are less than the minimum recommended feature size of 0.020 in. If possible try to use common fonts such as “arial” or “veranda” because they are designed to print clearly even at smaller sizes.

Hollow Parts – Hollow prototype parts are great because reduction in volume reduces cost and build time.

D. Surface Finishes

Basic and advanced surface finishes may be applied to prototypes produced using this technology. All surfaces are sand-blasted and prepared for further finishing. This 3D printing technology is great for prototype parts that require painted outer surface preparation in order to function as working visual representation models.

E. Applications

Parts produced using this technology are mostly suited for form, fit, and function testing. This technology has a multitude of strengths including design and material flexibility, and the overall low cost of materials. Prototypes made from this technology allow for commercial product testing, functional assembly, public surveys, field testing, and visual & aesthetic evaluation.

Created by RedOrum