Analysis of Tribo-Charging during Powder Spreading in Selective Laser Sintering: Assessment of Polyamide 12 Powder Ageing Effects on Charging Behavior

Hesse, Nicolas; Dechet, Maximilian A.; Bonilla, Juan S. Gómez; Lübbert, Christian; Roth, Stephan; Bück, Andreas; Schmidt, Jochen; Peukert, Wolfgang

doi:10.3390/polym11040609

Cited by 25 publications

(18 citation statements)

References 39 publications

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“…The cylindrical inner part was selected from a range of conventional industrial materials and was, therefore, not restricted by the limited materials selection associated with LPBF. Polyamide 12 (Nylon 12) was chosen as a relatively low-CTE material for the lattice outer part because it processes well by LPBF to enable complex parts to be manufactured with a good combination of geometrical accuracy and mechanical performance [32]. Ultra-high-molecular-weight polyethylene (UHMWPE) was chosen as a relatively high-CTE material for the cylindrical inner part because it provides a high value of CTE, good impact resistance, very low coefficient of friction, and self-lubricating performance [33], which is advantageous in the assembly and performance of the proposed two-material structure.…”

Section: Motivation and Lattice Design Conceptmentioning

confidence: 99%

Low Thermal Expansion Machine Frame Designs Using Lattice Structures

et al. 2021

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In this work, we investigated tessellating cellular (or lattice) structures for use in a low thermal expansion machine frame. We proposed a concept for a lattice structure with tailorable effective coefficient of thermal expansion (CTE). The design is an assembly of two parts: a lattice outer part and a cylindrical inner part, which are made of homogenous materials with different positive CTEs. Several lattice design variations were investigated and their thermal and mechanical performance analysed using a finite element method. Our numerical models showed that a lattice design using Nylon 12 and ultra-high molecular weight polyethylene could yield an effective in-plane CTE of 1 × 10−9 K−1 (cf. 109 × 10−6 K−1 for solid Nylon 12). This paper showed that the combination of design optimisation and additive manufacturing can be used to achieve low CTE structures and, therefore, low thermal expansion machine frames of a few tens of centimetres in height.

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Section: Motivation and Lattice Design Conceptmentioning

confidence: 99%

Low Thermal Expansion Machine Frame Designs Using Lattice Structures

et al. 2021

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“…The geometrical flexibility of the parts produced by Selective Laser Sintering (SLS) represents the top characteristic of this technology [1][2][3]. Commonly, SLS technology uses the energy of a laser beam in addition to an electrical heating source in order to generate a high enough temperature for particle bonding.…”

Section: Introductionmentioning

confidence: 99%

Mode I Fracture Toughness of Polyamide and Alumide Samples obtained by Selective Laser Sintering Additive Process

2020

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Selective Laser Sintering is a flexible additive manufacturing technology that can be used for the fabrication of high-resolution parts. Alongside the shape and dimension of the parts, the mechanical properties are essential for the majority of applications. Therefore, this paper investigates dimensional accuracy and mode I fracture toughness (KIC) of Single Edge Notch Bending samples under a Three Point Bending fixture, according to the ASTM D5045-14 standard. The work focuses on the influence of two major aspects of additive manufacturing: material type (Polyamide PA2200 and Alumide) and part orientation in the building environment (orientations of 0°, 45° and 90° are considered). The rest of the controllable parameters remains constant for all samples. The results reveal a direct link between the sample densities and the dimensional accuracy with orientation. The dimensional accuracy of the samples is also material dependent. For both materials, the angular orientation leads to significant anisotropic behavior in terms of KIC. Moreover, the type of material fundamentally influences the KIC values and the fracture mode. The obtained results can be used in the development of additive manufactured parts in order to obtain predictable dimensional tolerances and fracture properties.

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“…Ideally, suitable SLS polymeric materials should have low melt viscosity and low surface tension to ensure sufficient coalescence of material without extra compacting [2,6]. Furthermore, the surface tension of the melt influences the sinking depth of the melt into the powder bed, which in turn influences the dimensional accuracy and surface roughness of printed parts [8]. Lastly, most polymers absorb the CO2 laser beam and therefore melt because their optical properties are suitable to the use of this beam [3].…”

Section: Introductionmentioning

confidence: 99%