Selective Laser Sintering (SLS) is an additive manufacturing technique that bonds or sinters powdered materials into solid three-dimensional (3D) objects as the particles are thermally fused with a laser layer by layer. Advances in SLS technology have led to the development of complex components using thermoplastic polymers, ceramics, and metal powders. Advantages of SLS 3D printing compared to traditional injection molding include part complexity, controlled porosity, and superior mechanical properties for most polymers. These include commonly used polymers, such as polyamide and polystyrene, which are already commercially used for SLS due to their relatively low melting temperatures and thermal coefficients of expansion. However, additive manufacturing of high-performance polymers with high melting temperature using SLS, such as Polyetheretherketone (PEEK) and High-Density Polyethene (HDP`E), remain challenging. Their high thermal coefficients of expansion can result in poor printing quality and imperfection, such as embedded void and surface curling, and reduced mechanical properties compared to traditional manufacturing methods, such as injection molding. Therefore, the overall objective of this paper is to investigate and develop a set of additive manufacturing parameters for SLS technology that can lead to high quality and controllable microstructures in printed polymersIn this paper the processing parameters for 3D printing of HDPE via SLS technology is explored. Five different print types are developed by varying the output power of laser, chamber temperature, and scanning speeds between 10 mm/s and 80 mm/s in order to determine the optimal printing parameters that are needed for the manufacturing of consistent porous HDPE parts. The porosity of each print type is investigated via scanning electron microscopy (SEM). Experimental results demonstrates that Print Types I – IV have significant melted regions on the top layers of the print likely due to the absorption of heat overtime. This can lead to the observed curling phenomenon. Therefore, Print Type V is developed to eliminate curling by progressively increasing the scanning speed at increments of 1 mm/s between each layer, which can result in the desired HDPE prints with consistent porosity and drastically increased printability of complex geometries. Additionally, density, porosity, and mechanical properties are characterized for each print type. Experimental results show that Print Type IV samples prove to be superior in terms of ultimate tensile strength, elongation at fracture, and tensile modulus due to the largest melted regions. Print Type V produces samples with 47% weaker strength and 27% weaker modulus. However, they exhibit uniform porosity and eliminated part curling. Print Type V printing parameters are used to produce various HDPE prints with high quality and complex geometries.&nbsp;

Investigation of Selective Laser Sintering of High-Density Polyethylene Using Optimized 3d Printing Parameters

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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