The effect of ageing process on three-point bending strength and permeability of 3D printed sand molds

International audienceThe objective of this paper was to investigate the effects of curing parameters (i.e., temperature and time), on the permeability and mechanical strength of the printed molds. Several sets of samples were hence produced with a state-of-the-art 3D printer using well-characterized silica sand and furan resin binder. Then, experiments were performed in which the evolution over time of the three-point bending (3 PB) strength and permeability of the samples were monitored at three different curing temperatures. From these measurements, both the individual and combined effects of curing temperature and time on the functionality of the 3D printed molds were assessed. Moreover, loss-on-ignition (LOI) tests were also performed in order to relate the loss of binder mass to the variation in permeability and mechanical strength of the samples. The results showed that the printed molds can be stored at room temperature for a long time before being used, roughly preserving the initial properties. No significant change in 3 PB strength was observed when curing at 100 °C. In contrast, the permeability was shown to decrease with increasing curing temperature

On the rapid manufacturing process of functional 3D printed sand molds

3D printing sand mold technology offers an opportunity for the foundry industry to rethink old casting approaches and to revive the manufacturing approach using computer models. One of the major concerns in sand molding using 3D printing is the functional characterization of the 3D printed molds as its mechanical and mass transport properties. This research paper discusses the effects of binder content on the mechanical strength and the permeability of 3DP sand molds at different curing conditions. The local permeability of the 3DP specimen was measured as a function of the injection flow rate in order to quantify the inertial pressure effects. The mechanical strength of the 3DP sand molds was characterized using traditional three-point bending strength measurements. The results show that the mechanical strength of the printed molds is deeply dependent on the amount of binder and the curing process. The 3PB strength was found to increase when cured at 100 °C and decrease when cured at 200 °C for all binder contents. The 3PB strength attains its maximum when cured at 100 °C for 2 h for all binder content. In contrast, no significant effect of the amount of binder on the initial permeability of the samples before curing was observed within the functional range of binder mass fraction (1.02–1.98 %). Maximum permeability is attained at the same conditions as the 3PB strength. Therefore, the mechanical strength of the sample can be optimized within the investigated range of binder contents without resulting in any significant decrease in permeability

The effect of ageing process on three-point bending strength and permeability of 3D printed sand molds

The objective of this paper was to investigate the effects of curing parameters (i.e., temperature and time), on the permeability and mechanical strength of the printed molds. Several sets of samples were hence produced with a state-of-the-art 3D printer using well-characterized silica sand and furan resin binder. Then, experiments were performed in which the evolution over time of the three-point bending (3 PB) strength and permeability of the samples were monitored at three different curing temperatures. From these measurements, both the individual and combined effects of curing temperature and time on the functionality of the 3D printed molds were assessed. Moreover, loss-on-ignition (LOI) tests were also performed in order to relate the loss of binder mass to the variation in permeability and mechanical strength of the samples. The results showed that the printed molds can be stored at room temperature for a long time before being used, roughly preserving the initial properties. No significant change in 3 PB strength was observed when curing at 100 °C. In contrast, the permeability was shown to decrease with increasing curing temperature

On the rapid manufacturing process of functional 3D printed sand molds

3D printing sand mold technology offers an opportunity for the foundry industry to rethink old casting approaches and to revive the manufacturing approach using computer models. One of the major concerns in sand molding using 3D printing is the functional characterization of the 3D printed molds as its mechanical and mass transport properties. This research paper discusses the effects of binder content on the mechanical strength and the permeability of 3DP sand molds at different curing conditions. The local permeability of the 3DP specimen was measured as a function of the injection flow rate in order to quantify the inertial pressure effects. The mechanical strength of the 3DP sand molds was characterized using traditional three-point bending strength measurements. The results show that the mechanical strength of the printed molds is deeply dependent on the amount of binder and the curing process. The 3PB strength was found to increase when cured at 100 °C and decrease when cured at 200 °C for all binder contents. The 3PB strength attains its maximum when cured at 100 °C for 2 h for all binder content. In contrast, no significant effect of the amount of binder on the initial permeability of the samples before curing was observed within the functional range of binder mass fraction (1.02–1.98 %). Maximum permeability is attained at the same conditions as the 3PB strength. Therefore, the mechanical strength of the sample can be optimized within the investigated range of binder contents without resulting in any significant decrease in permeability

The effect of ageing process on three-point bending strength and permeability of 3D printed sand molds

The objective of this paper was to investigate the effects of curing parameters (i.e., temperature and time), on the permeability and mechanical strength of the printed molds. Several sets of samples were hence produced with a state-of-the-art 3D printer using well-characterized silica sand and furan resin binder. Then, experiments were performed in which the evolution over time of the three-point bending (3 PB) strength and permeability of the samples were monitored at three different curing temperatures. From these measurements, both the individual and combined effects of curing temperature and time on the functionality of the 3D printed molds were assessed. Moreover, loss-on-ignition (LOI) tests were also performed in order to relate the loss of binder mass to the variation in permeability and mechanical strength of the samples. The results showed that the printed molds can be stored at room temperature for a long time before being used, roughly preserving the initial properties. No significant change in 3 PB strength was observed when curing at 100 °C. In contrast, the permeability was shown to decrease with increasing curing temperature

Study of the evolution of transport properties induced by additive processing sand mold using X-ray computed tomography

Accurate characterization of the mass transport properties of additively processed sand molds is essential in order to achieve reproducibility of the produced castings and control of gas defects in foundry industries. The present work highlights the potential use of X-ray micro-computed tomography (μ-CT) to characterize the evolution of permeability and some major microstructural features of such additively processed sand molds. The evolution of mass transport properties of sand mold samples under specific processing conditions met in additive manufacturing and its influence on the porosity, the permeability, the tortuosity, and the pore and throat size distributions were characterized from 3D images provided by X-Ray μ-CT. The obtained results showed that the mass transport properties of additively processed sand molds can be closely predicted by using non-destructive in situ methods, such that improvements to the casting can be made to create more optimized 3D printed structures for foundry applications

Caractéristique expérimentale et numérique des propriétés fonctionnelles des moules sables produits par fabrication additive ( procédé d'impression 3D par projection de liant) en fonderie rapid

Nowadays, traditionally manufactured sand molds and cores for metal casting are being progressively replaced by additively processed sand molds in aerospace/automotive industry, facilitating the production of quality cast parts with complex shapes. The type of additive manufacturing technology used to manufacture 3DP parts in foundries is known as powder-binder-jetting process. In this technology, the molds are produced without the use of any kind of additive tools and in a completely automated way using the layer based construction method. One of the most popular binder systems used in the manufacturing of 3DP mold is a furan-based resin binder, which holds the grain particles together. Their amounts and ratios can influence significantly the 3D printed mold properties, affecting casting quality. Therefore, it is essential to characterize the effects process parameters on the functionality of the 3DP molds. In the present work, the mechanical behavior of 3DP sand molds with varying printing process parameters was first investigated, followed by mass transport properties. To do so, a series of three-point bending strength tests, density measurements, porosity measurements and permeability tests were performed on the 3DP molds. Furthermore, the influence of time, temperature and binder volume fraction on the mechanical and mass transport properties was also investigated. Advanced modelling of the pore space was performed by using the reconstructed images provided by X-ray computed tomography, following different steps: X-ray CT scanning of small 3DP mold specimen, 3D volumetric reconstruction of data, numerical simulations for the prediction of permeability from the reconstructed volume, and pore network modelling for the determination of the pore size distribution. Experiments were also designed to investigate the 3D printed molds in terms of mold erosion during metal casting, in order to select the molding parameters to print 3D printed parts not only with good mechanical and mass transport properties but also to minimize the mold erosion during metal casting. Furthermore, a reverse engineering method for determination of the erosion resistance of sand molds has been established, to study the volume of the eroded surface.Les techniques traditionnelles pour la production des moules et des noyaux en sable utilisés en fonderie pour la coulée de métaux sont actuellement en cours de remplacement par des méthodes de fabrication additive, afin d'aider l’industrie aérospatiale/automobile à fabriquer des pièces de forme complexe d'une manière pratique. Le but de ce travail de recherche est d'étudier les propriétés fonctionnelles des moules imprimés en 3D utilisés lors de la coulée des pièces de forme complexe pour des applications d'ingénierie. Premièrement, le comportement mécanique des moules en sables imprimés en 3D a été analysé et caractérisé pour de différents paramètres du processus d'impression. Ensuite, les propriétés mécaniques et de transport de masse des moules en sable 3DP ont été étudiées. Les pièces imprimées en 3D pour la fonderie sont souvent fabriquées avec un type de technologie de fabrication additive appelé « powder-binder-jetting process » (processus de projection de liant de poudre). Des mesures sur trois points de la force de flexion, la densité, la porosité et la perméabilité, ont été effectués sur les moules fabriqués avec la technologie additive. En plus, l’influence de la température et de la fraction volumique du liant sur les propriétés mécaniques et de transport de masse a également été étudiée. Par ailleurs, la perméabilité des moules en sable imprimé a aussi été caractérisée par micro-tomographie de rayons X, permettant la modélisation avancée de la microstructure poreuse en suivant plusieurs étapes : 1) tomodensitométrie de petits échantillons de moules 3DP, 2) reconstruction volumétrique 3D de données, 3) simulation numérique pour la prédiction de la perméabilité à partir de volumes reconstruits et 4) modélisation du réseau de pores pour déterminer la distribution de la taille des pores et des constrictions. Des expériences ont également été conçues pour étudier les moules imprimés en 3D en termes de leur érosion lors de la coulée des métaux. Cela a permis d’identifier les paramètres optimaux du procédé d’impression 3D des moules, non seulement en termes de leurs propriétés mécaniques et de transport de masse, mais aussi pour minimiser l'érosion du moule durant la coulée métallique. Une méthode de détermination de la résistance à l'érosion des moules en sable a également été proposée, sur la base de la mesure du volume de la surface érodée à l'aide d'une technique d'ingénierie inverse moderne

On the rapid manufacturing process of functional 3D printed sand molds

International audience3D printing sand mold technology offers an opportunity for the foundry industry to rethink old casting approaches and to revive the manufacturing approach using computer models. One of the major concerns in sand molding using 3D printing is the functional characterization of the 3D printed molds as its mechanical and mass transport properties. This research paper discusses the effects of binder content on the mechanical strength and the permeability of 3DP sand molds at different curing conditions. The local permeability of the 3DP specimen was measured as a function of the injection flow rate in order to quantify the inertial pressure effects. The mechanical strength of the 3DP sand molds was characterized using traditional three-point bending strength measurements. The results show that the mechanical strength of the printed molds is deeply dependent on the amount of binder and the curing process. The 3PB strength was found to increase when cured at 100 °C and decrease when cured at 200 °C for all binder contents. The 3PB strength attains its maximum when cured at 100 °C for 2 h for all binder content. In contrast, no significant effect of the amount of binder on the initial permeability of the samples before curing was observed within the functional range of binder mass fraction (1.02–1.98 %). Maximum permeability is attained at the same conditions as the 3PB strength. Therefore, the mechanical strength of the sample can be optimized within the investigated range of binder contents without resulting in any significant decrease in permeability

The effect of ageing process on three-point bending strength and permeability of 3D printed sand molds

International audienceThe objective of this paper was to investigate the effects of curing parameters (i.e., temperature and time), on the permeability and mechanical strength of the printed molds. Several sets of samples were hence produced with a state-of-the-art 3D printer using well-characterized silica sand and furan resin binder. Then, experiments were performed in which the evolution over time of the three-point bending (3 PB) strength and permeability of the samples were monitored at three different curing temperatures. From these measurements, both the individual and combined effects of curing temperature and time on the functionality of the 3D printed molds were assessed. Moreover, loss-on-ignition (LOI) tests were also performed in order to relate the loss of binder mass to the variation in permeability and mechanical strength of the samples. The results showed that the printed molds can be stored at room temperature for a long time before being used, roughly preserving the initial properties. No significant change in 3 PB strength was observed when curing at 100 °C. In contrast, the permeability was shown to decrease with increasing curing temperature

Study of the evolution of transport properties induced by additive processing sand mold using X-ray computed tomography

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