Selective laser sintering of ceramic powders with bimodal particle size distribution

Sofia, Daniele; Chirone, Roberto; Lettieri, Paola; Poletto, Massimo

doi:10.1016/j.cherd.2018.06.008

Cited by 52 publications

(26 citation statements)

References 37 publications

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“…Although there has been much investigation on the influence of process parameters and material compounds on the mechanical properties of polymers such as PA12 [4,5,6,7], the effect of the powder deposition process is not yet well understood. For this purpose, a number of experimental and numerical related approaches helped to gain new insights into the topic of creating dense packings and made it possible to better evaluate the powder flow properties [8,9,10,11,12]. Further investigations, such as the determination of appropriate particle sizes for SLS [13] and particle size distributions (PSD) [10], along with new ways of quantifying powder flow properties [12,14] showed that powder characterization still lacks appropriate methods.…”

Section: Introductionmentioning

confidence: 99%

Influence of Powder Deposition on Powder Bed and Specimen Properties

et al. 2019

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Three-dimensional printing used to be a rapid prototyping process, but nowadays it is establishing as an additive manufacturing (AM) process. One of these AM techniques is selective laser sintering (SLS), which most often involves partial melting of the particles and therefore belongs to the category of powder bed fusion processes. Much progress has been made in this field by research on process parameters like laser power, hatch distance, and scanning speed while still lacking a fundamental understanding of the powder deposition and its influence on parts. A critical issue for economic manufacturing is the building time of parts with good mechanical properties, which can be reduced by lower surface roughness due to less or missing post processing. Therefore, the influence of three blade shapes on powder bed surface roughness has been evaluated for PA12 powder with three different grain size distributions by using advanced X-ray micro computed tomography (XMT) and a confocal laser scanning microscope (LSM). Along with those methods, new techniques for powder characterization were tested and compared. Lowest roughness has been achieved with a flat blade, based on a higher compression due to a larger contact zone between blade and powder bed. Furthermore, an anisotropic effect of the mechanical properties resulting from different building directions has been detected which can be explained by varying amounts of solid contact paths through the powder bed depending on powder application direction. In addition, an optimal combination of process parameters with an even compression of the powder bed leads to low surface roughness, complementing the advantages of additive manufacturing.

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Section: Introductionmentioning

confidence: 99%

Influence of Powder Deposition on Powder Bed and Specimen Properties

et al. 2019

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“…Several mechanisms, i.e. dissolution-crystallisation [8], sintering [9,10] and supersaturations (Ostwald caking [11]) are responsible for solid bridges. In sintering [9], particles coalesce, by bridging between two or more particles.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Development and application of a novel cake strength tester

et al. 2019

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Caking can cause many problems in industries during processing or storage of particulate materials. Caking magnitude depends on several factors, for instance temperature, consolidation stress and storage time. In this research paper, a novel force displacement and easy-to-use caking tester for measuring quantitatively cake strength as a result of elevated temperature, consolidation stress and storage time is introduced. The developed tester outweighed the conventional uniaxial unconfined failure caking tester due to the defined location of the failure plane to maximise repeatability, the necessity for a lower quantity of powder, maximised exposed surface and lower wall friction as well as production costs. The experimental design has been conducted by changing the temperature, consolidation stress and storage duration. The results showed that the tester could distinguish cake strength between different experimental conditions. A statistical model has been successfully developed to study the effect of each variable on the cake strength.

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“…PA12 nylon sample was collected and undergo size analysis. The tabulation size of PA12 powder before SLS 3D printing process were analysed to measured particulate matter exposed during powder preparation phase [30].…”

Section: Characterizationmentioning

confidence: 99%

Indoor Air Concentration from Selective Laser Sintering 3D Printer using Virgin Polyamide Nylon (PA12) Powder: A Pilot Study

Damanhuri¹,

Hariri

Alkahari³

et al. 2019

IJIE

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Environmental emissions from additive manufacturing (AM) have attracted much attention recently. The capability in fabricating complex part make AM famous in developing prototype and product in various industries, especially in aerospace, medical, automotive, and manufacturing industries. However, the study on emission and exposure mainly focusses on the desktop type such as fused deposition modelling. This study investigates the emission and indoor concentration from powder bed fusion of selective laser sintering (SLS) technologies. Prior to the investigation, virgin PA12 has undergone characterization in terms of morphology, size and thermal analysis. Calibration block using virgin polyamide nylon (PA12) is selected to be printed in this study. Parameters such particulate matter size 2.5 µm (PM 2.5), total volatile organic compound (TVOC), carbon dioxide (CO 2), formaldehyde, temperature and relative humidity (RH) are set to be monitored through real-time sampling of 8 hours based on Industry Code of Practice on Indoor Air Quality 2010 by Department Occupational Safety and Health (DOSH) Malaysia. Four phases of the printing process involve are background data, preprinting, during printing and post-printing. Based on the study it was found that PM 2.5 and CO 2 exceed the acceptable limit recommended by DOSH Malaysia during the preparation of powder (preprinting) at 1218 ppm and 1070 µg/m 3 respectively. Meanwhile TVOC concentration was influenced by the sintered powder temperature and recorded at 0.5 ppm. Temperature, relative humidity and formaldehyde were maintained throughout the SLS process. Mitigation strategies using mechanical ventilation and personal protective equipment (PPE) are recommended to be used to reduce the potential of occupational hazard to the operators.

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Selective laser sintering of ceramic powders with bimodal particle size distribution

Cited by 52 publications

References 37 publications

Influence of Powder Deposition on Powder Bed and Specimen Properties

Influence of Powder Deposition on Powder Bed and Specimen Properties

Development and application of a novel cake strength tester

Indoor Air Concentration from Selective Laser Sintering 3D Printer using Virgin Polyamide Nylon (PA12) Powder: A Pilot Study

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