Methodology for determining design rules for helical channels in glass components produced by selective laser sintering

Abstract

Selective laser sintering (SLS) is used widely for additive manufacturing because of its many advantages including the ability to produce complex part geometries without trapping material in internal cavities, manufacturing speed, and reliable mechanical properties for the produced parts. 1 SLS utilizes a laser, powder feed system, heated powder bed, and heated build chamber to produce geometrically complex, three-dimensional parts. A slicing program takes an imported CAD model and transforms it into two-dimensional layers that are approximately 100 µm thick. The powder feed system spreads powder onto the preheated powder bed using a counter-rotating roller. After powder deposition, the laser precisely scans the powder bed utilizing a pair of galvanometers according to the two-dimensional model created by the slicer.The combination of preheating and the laser is used to bring the powder slightly above the melting point, allowing it to selectively bond to surrounding particles as well as to the powder layer below it. Following scanning of each layer, the piston supporting the power bed is lowered, another layer is spread, and the process is repeated until the fabrication is complete.Polymers such as nylon 11 and 12 are often used for direct selective laser sintering, due to their relatively large thermal processing windows and relatively low melting temperatures. Design rules have been studied extensively to provide guidelines to successfully resolve features for parts made with this process. Examples of design guidelines for SLS can be found in work by Allison et al 2,3 and Adam and Zimmer. 4 Studies have also been done to validate the strength, 5 surface roughness, 6 and porosity 7 of parts produced in this manner to drive design for end-use parts. Research in this field has focused on simple