Impact of extended sintering times on mechanical properties in PA-12 parts produced by powderbed fusion processes

Craft, Garrett; Nussbaum, Justin; Crane, Nathan B.; Harmon, Julie P.

doi:10.1016/j.addma.2018.06.028

Cited by 50 publications

(37 citation statements)

References 21 publications

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“…The investigation of processing conditions on parts obtained from SLS has been the object of extensive experimental studies [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64]. Part density is unanimously recognised as the principal variable affecting the mechanical behaviour of laser-sintered components.…”

Section: Selective Laser Sinteringmentioning

confidence: 99%

“…The so-called overlay ratio, Cauchy stress, defined as the ratio between the laser beam diameter and the scan spacing OL ¼ D b =s, has been shown to play a fundamental role on the mechanical properties of the printed components and was recently included in the definition of the surface energy density [58]. In general, all the experimental studies confirm a positive correlation of E b with mechanical properties such as Young's modulus, yield stress, ultimate tensile strength and elongation at break [48][49][50][51][52][53][54][55][56][57][58][59][60] (Fig. 3).…”

Section: Selective Laser Sinteringmentioning

confidence: 99%

“…The motivation is imputed to the increased density of parts processed at high energy densities: by contrast, at lower energies the sintering process is incomplete and parts usually show a porous structure with interconnected voids [48]. However, there exists an optimal value of E b beyond which the porosity of the part is again increased, due to phenomena of thermal degradation, which results in the emission of gas, formation of large voids [48,57] and change in the chemical structure of the material [51,52]. Higher densities and better mechanical performances have also been correlated with higher pre-heating temperatures in polyamide parts.…”

Section: Selective Laser Sinteringmentioning

confidence: 99%

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Laser-based additively manufactured polymers: a review on processes and mechanical models

et al. 2020

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Additive manufacturing (AM) is a broad definition of various techniques to produce layer-by-layer objects made of different materials. In this paper, a comprehensive review of laser-based technologies for polymers, including powder bed fusion processes [e.g. selective laser sintering (SLS)] and vat photopolymerisation [e.g. stereolithography (SLA)], is presented, where both the techniques employ a laser source to either melt or cure a raw polymeric material. The aim of the review is twofold: (1) to present the principal theoretical models adopted in the literature to simulate the complex physical phenomena involved in the transformation of the raw material into AM objects and (2) to discuss the influence of process parameters on the physical final properties of the printed objects and in turn on their mechanical performance. The models being presented simulate: the thermal problem along with the thermally activated bonding through sintering of the polymeric powder in SLS; the binding induced by the curing mechanisms of light-induced polymerisation of the liquid material in SLA. Key physical variables in AM objects, such as porosity and degree of cure in SLS and SLA respectively, are discussed in relation to the manufacturing process parameters, as well as to the mechanical resistance and deformability of the objects themselves. Graphic abstract

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Section: Selective Laser Sinteringmentioning

confidence: 99%

Section: Selective Laser Sinteringmentioning

confidence: 99%

Section: Selective Laser Sinteringmentioning

confidence: 99%

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Laser-based additively manufactured polymers: a review on processes and mechanical models

et al. 2020

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“…High speed sintering (HSS) is another similar 3D-printing process like MJF. The HSS 3D-printing process also jets an infrared absorbing ink that polymerizes the powder under infrared heat [ 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 ]. However, HSS 3D-printing process does not use detailing agent or transforming agent to improve accuracy, print detail, color and change material property [ 107 , 120 ].…”

Section: Powder-based 3d-printing Modalities and Their Resolutionmentioning

confidence: 99%

Powder-Based 3D Printing for the Fabrication of Device with Micro and Mesoscale Features

et al. 2020

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Customized manufacturing of a miniaturized device with micro and mesoscale features is a key requirement of mechanical, electrical, electronic and medical devices. Powder-based 3D-printing processes offer a strong candidate for micromanufacturing due to the wide range of materials, fast production and high accuracy. This study presents a comprehensive review of the powder-based three-dimensional (3D)-printing processes and how these processes impact the creation of devices with micro and mesoscale features. This review also focuses on applications of devices with micro and mesoscale size features that are created by powder-based 3D-printing technology.

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“…LS fabrication with DBM particulates has not been reported previously. However, a composite of DBM and polycaprolactone (PCL) and the mixture has been fabricated by fused deposition modeling (FDM) [15] and large area projection sintering (LAPS) [16]. Hung et al fabricated DBM/PCL scaffolds containing up to 70 wt % DBM using FDM [17].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Laser Sintering for Demineralized Bone/Polycaprolactone Composite Powder for Bone Tissue Scaffold

Ziaee

Mahmood

Crane

2020

JMMP

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Demineralized bone matrix (DBM) is an excellent bone scaffold material, but is available in only limited sizes. An additive manufacturing (AM) method that retains these properties while enabling customized geometry fabrication would provide bone scaffolds for a larger range of geometries while maintaining the benefits of DBM. This work examines laser sintering (LS) of a blend of demineralized bone matrix (DBM) and polycaprolactone (PCL) using a CO2 laser beam. A comprehensive experimental study was carried out to find the conditions that form defect-free layers while still retaining the favorable biological features of DBM. The results identify a process setting window over which LS can be utilized to constructing complex patient-specific scaffolds. With the identified setting, first, the DBM/PCL blend was fused in the LS machine. Parts were then were further strengthened through a post-processing heat treatment. The shrinkage level, skeletal density, mechanical testing, and porosimetry of the resultant samples were compared to traditional machined DBM blocks. The maximum tensile strength of the samples and post-processing shrinkage depends on heat treatment duration. The tensile strength measurements demonstrate that the post-processing conditions can be tuned to achieve the tensile strength of the demineralized bone strips. Evaluation of the dimensional change suggests that the shrinkage along the laser paths is ~0.3% while thickness shrinks the most (up to ~20%). The porosimetry and density studies showed that the final part achieved over 40% porosity with a density comparable to blocks of DBM.

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Impact of extended sintering times on mechanical properties in PA-12 parts produced by powderbed fusion processes

Cited by 50 publications

References 21 publications

Laser-based additively manufactured polymers: a review on processes and mechanical models

Laser-based additively manufactured polymers: a review on processes and mechanical models

Powder-Based 3D Printing for the Fabrication of Device with Micro and Mesoscale Features

Optimization of Laser Sintering for Demineralized Bone/Polycaprolactone Composite Powder for Bone Tissue Scaffold

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