The influence of the energy density on dimensional, geometric, mechanical and morphological properties of SLS parts produced with single and multiple exposure types

Lopes, Ana C.; Sampaio, Álvaro M.; Pontes, A. J.

doi:10.1007/s40964-021-00254-7

Cited by 8 publications

(9 citation statements)

References 33 publications

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“…According to the given Equation ( 1), Lopes et al found that varying energy densities impact the tensile properties of polyamide 12 made by selective laser sintering. Results from tensile testing show that the implementation of a skin/core configuration allows the production of SLS parts with a valuable set of properties, minimizing the trade-off between mechanical strength and overall accuracy [16].…”

Section: Introductionmentioning

confidence: 99%

Impact of Part Positioning along Chamber Z-Axis and Processing Parameters in Selective Laser Sintering on Polyamide Properties

Pilipović,

Ilinčić,

Tujmer

et al. 2024

Applied Sciences

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Additive manufacturing procedures are being increasingly developed, from prototyping to finished functional products. However, their rapid development also brings along the testing of properties with different manufacturing parameters. In selective laser sintering, the most influential manufacturing parameter is the energy density, which also consists, among other things, of the hatch distance. For better usage of the entire chamber and a reduction in the overall price of the finished product, in practice, the manufacturing of products at different heights (levels) of the working chamber with different orientations is inevitable. The study examines how hatch distance and product orientation impact the tensile strength and dimensional stability of polyamide products across two levels within the chamber. Upon analysis, it was observed that manufacturing products at different levels within the working chamber does not influence their dimensions. Achieving precise product dimensions comparable to those in the CAD model is possible. Furthermore, the same factors (orientation and hatch distance) and their combinations affect the length, thickness, and width of the product. Although all test specimens were tested, a tensile strength analysis of variance (ANOVA) of test specimens produced at the lower level of the chamber with a combination of hatch distance (ranging from 0.23 to 0.6 mm) and orientation (ranging from 0° to 60°) was not feasible in the design of the experiment. Despite this limitation, it was noted that both chamber levels had the potential to reach a maximum tensile strength of 47 N/mm2. Nevertheless, the average tensile strength of PA12, obtained through combinations of input factors, stood at only 30 N/mm2, which is quite a low value for polyamide made by selective laser sintering.

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Section: Introductionmentioning

confidence: 99%

Impact of Part Positioning along Chamber Z-Axis and Processing Parameters in Selective Laser Sintering on Polyamide Properties

Pilipović,

Ilinčić,

Tujmer

et al. 2024

Applied Sciences

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“…When the energy input to the powder particles increases, the porosity of parts decreases and the density and mechanical properties increase until degradation begins (Czelusniak and Amorim, 2020;Tong et al, 2020). For PA12, values between 0.158 and 0.238 J/mm 3 are adequate for dimensional and geometric properties and values between 0.278 and 0.318 J/mm 3 for mechanical strength (Lopes et al, 2022b). In turn, the processing of carbon-based composite materials requires specific adjustment of the sintering variables, as this type of reinforcement intensifies the conduction of the energy supplied by the laser beam through the layers of powder Figure 1 Schematics of SLS process compared to conventional thermoplastics such as polyamides (Salmoria et al, 2011;Bai et al, 2013Bai et al, , 2015.…”

Section: Introductionmentioning

confidence: 99%

“…Selective laser sintering (SLS) is a powder bed fusion technology wherein polymeric parts are produced through powder material that is fused by the thermal energy of a laser source according to a previously sliced computer-aided design model (ASTM, 2012; Lopes et al , 2022b). For processing, conventional laser-sintering systems comprise: a closed chamber for thermal and atmospheric control; powder bins for material feeding; a recoater for powder dosing and dispensing; a building platform for the layer-by-layer manufacturing; and an optical system including the laser source and scanning mirrors (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Development and characterization of composite materials with multi-walled carbon nanotubes and graphene nanoplatelets for powder bed fusion

Lopes,

Sampaio,

Pontes

2023

RPJ

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Purpose With the technological progress, high-performance materials are emerging in the market of additive manufacturing to comply with the advanced requirements demanded for technical applications. In selective laser sintering (SLS), innovative powder materials integrating conductive reinforcements are attracting much interest within academic and industrial communities as promising alternatives to common engineering thermoplastics. However, the practical implementation of functional materials is limited by the extensive list of conditions required for a successful laser-sintering process, related to the morphology, powder size and shape, heat resistance, melt viscosity and others. The purpose of this study is to explore composite materials of polyamide 12 (PA12) incorporating multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GNP), aiming to understand their suitability for advanced SLS applications. Design/methodology/approach PA12-MWCNT and PA12-GNP materials were blended through a pre-optimized process of mechanical mixing with various percentages of reinforcement between 0.50 wt.% and 3.00 wt.% and processed by SLS with appropriate volume energy density. Several test specimens were produced and characterized with regard to processability, thermal, mechanical, electrical and morphological properties. Finally, a comparative analysis of the performance of both carbon-based materials was performed. Findings The results of this research demonstrated easier processability and higher tensile strength and impact resistance for composites incorporating MWCNT but higher tensile elastic modulus, compressive strength and microstructural homogeneity for GNP-based materials. Despite the decrease in mechanical properties, valuable results of electrical conductivity were obtained with both carbon solutions until 10–6 S/cm. Originality/value The carbon-based composites developed in this research allow for the expansion of the applicability of laser-sintered parts to advanced fields, including electronics-related industries that require functional materials capable of protecting sensitive devices against electrostatic discharge.

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“…Czelusniak et al [16] found that the mechanical and geometric properties of PA12 parts improve with the increase of laser energy density, but too high laser energy will weaken the performance. Lopes et al [17] discovered the energy density has a signi cant in uence on the dimensional accuracy of SLS-manufactured parts of PA12 material. Obviously, the quality of SLS printed part is highly dependent on the laser energy density.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the effect of laser energy density on selective laser sintering of PA12 using a multi-physics field simulation method

Li,

Zhao,

Yang

et al. 2023

Int J Adv Manuf Technol

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Selective laser sintering (SLS) polymer powders involve multi-physical eld transient phenomena that are critical to the optimization of SLS process parameters, but challenging to observe experimentally. In this study, a two-dimensional multi-physics eld simulation method was used to couple the thermal-force-ow elds involved in SLS. Laser energy density was introduced to characterize the interaction between process parameters such as laser power and scanning speed, and the free surface evolution, material migration, and molten pool evolution of nylon 12 (PA12) at different energy densities were thoroughly investigated. Accordingly, the optimal process parameters for SLS were determined as laser energy density of 0.08 J/mm 2 , i.e., laser power 12 W, scanning pitch 0.12 mm and scanning speed 1500 mm/s. The same process parameters were then used to validate the simulation model. Experimental results show that the density, cross-sectional pro le and compression property are also the optimal with the same energy density of 0.08 J/mm 2 . Full agreement with the simulation results indicates that the multiphysics simulation method provides an effective approach for SLS parameter optimization.

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The influence of the energy density on dimensional, geometric, mechanical and morphological properties of SLS parts produced with single and multiple exposure types

Cited by 8 publications

References 33 publications

Impact of Part Positioning along Chamber Z-Axis and Processing Parameters in Selective Laser Sintering on Polyamide Properties

Impact of Part Positioning along Chamber Z-Axis and Processing Parameters in Selective Laser Sintering on Polyamide Properties

Development and characterization of composite materials with multi-walled carbon nanotubes and graphene nanoplatelets for powder bed fusion

Investigation of the effect of laser energy density on selective laser sintering of PA12 using a multi-physics field simulation method

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