Dataset Information

Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores.

ABSTRACT: Additive manufacturing of casting cores and molds is state of the art in industrial application today. However, improving the properties of chemically bonded casting cores regarding temperature stability, bending strength, and surface quality is still a major challenge. The process of slurry-based 3D printing allows the fabrication of dense structures and therefore sinterable casting cores. This paper presents a study of the slurry-based fabrication of ceramic layer compounds focusing on the drying process and the achievable properties in slurry-based 3D printing of casting cores. This study aims at contributing to a better understanding of the interrelations between the drying conditions in the 3D printing process and the properties of sintered specimens relating thereto. The drying intensity influenced by an IR heater as well as the drying periods are varied for layer thicknesses of 50, 75, and 100 µm. Within this study, a process window applicable for 3D printing of sinterable casting cores is identified and further indications are given for optimization potentials. At layer heights of 75 µm, bending strengths between ~8 and 11 MPa as well as densities of around 50% of the theoretical density were achieved. Since the mean roughness depth Rz is determined to be <30 µm in plane, an application of slurry-based 3D printing in investment casting is conceivable.

SUBMITTER: Erhard P

PROVIDER: S-EPMC8539653 | biostudies-literature | 2021 Oct

REPOSITORIES: biostudies-literature

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Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores.

Erhard Patricia P Angenoorth Jan J Vogt Joachim J Spiegel Johannes J Ettemeyer Florian F Volk Wolfram W Günther Daniel D

Materials (Basel, Switzerland) 20211016 20

Additive manufacturing of casting cores and molds is state of the art in industrial application today. However, improving the properties of chemically bonded casting cores regarding temperature stability, bending strength, and surface quality is still a major challenge. The process of slurry-based 3D printing allows the fabrication of dense structures and therefore sinterable casting cores. This paper presents a study of the slurry-based fabrication of ceramic layer compounds focusing on the dry ...[more]

PMID: 34683742

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Project description:The mechanical and rheological characterizations of flexible investment casting patterns capable of 3D printing are reported. The wax pattern was composed of microcrystalline hydrocarbon wax (DMW7478), Piccotex 75 (a copolymer of α-methyl-styrene and vinyl toluene with a 75/25 molar ratio, respectively) and Escorene (a copolymer of ethylene and vinyl acetate with a 72/28 mass ratio, respectively). It was found that in order to obtain a wax pattern with appreciable mechanical properties, the content of the microcrystalline hydrocarbon wax in these blends should not exceed 30% (m/m). Thus, a series of patterns with 28% (m/m) wax and varying Piccotex and Escorene contents spanning from 0 to 72% (m/m) was prepared. The dependence of the dynamic viscosities of the wax patterns on the composition was described using a stretched exponential model, whereas their variations with the temperature were interpreted in terms of the Arrhenius-Guzman equation. Furthermore, the slopes of the lines fitted to the viscosity versus temperature curves at the pour point decreased linearly with the Piccotex content. Non-Newtonian changes in the shear stress with the shear rate and shear stress crystallization were observed at temperatures near the pour points. The mechanical properties were evaluated using the uniaxial tensile mode and by three-point bending experiments. It was found that the stress (σ) versus the relative elongation (ε) curves can effectively be rendered by means of the standard linear solid (SLS) viscoelastic model. In addition, it was also established that the Young's modulus varied according to a sigmoid-type curve with the piccotex content, while the yield stress decreased linearly with the concentration of Piccotex. In addition, based on the spooling suitability and printability, the patterns were rated and it was found that the most appropriate wax pattern compositions for 3D printing were those which contained 30% (m/m) and 35% (m/m) Piccotex.

Project description:BackgroundThree-dimensional (3D) printing technology has been utilized to create patient-specific (PS) replicas as visual aids for surgical planning.1-4 However, they cannot recreate the operative experience due to a lack of realistic tissue characteristics.ObjectivesDevelop anatomically accurate, realistic, PS partial nephrectomy platforms suitable for pre-operative surgical rehearsals using 3D-printing and hydrogel casting.MaterialPatient CT scans were segmented into a computer-aided design (CAD) file and used to create injection casts. Kidney and tumor casts along with hollow vascular and urinary structures were 3D-printed. The hilar structures and tumor were registered into the kidney cast, injected with poly-vinyl alcohol (PVA) hydrogel, and processed to create the kidney phantom. Mechanical and functional testing protocols were completed to confirm that the properties of PVA matched the live tissue.5 Anatomical accuracy was confirmed by CT scanning the phantom and creating another CAD, which was compared to the original patient CAD. Full-procedural PS rehearsals were completed 24-48 hours prior to their respective live surgeries. Clinically relevant metrics (warm ischemia time, estimated blood loss, and positive surgical margins) from each rehearsal and live case were compared using a Wilcoxon-rank sum test.ResultsThe 7%-3freeze/thaw PVA best recreated the mechanical and functional properties of porcine kidneys, while anatomical verification showed ≤1 mm deviation of the kidney and tumor from the patient anatomy and ≤3 mm for the hilar structures. PS rehearsal platforms were fabricated using these methods for 8 patients (average tumor size 5.92 cm and nephrometry score 9.8). A positive correlation was found for warm ischemia time and estimated blood loss between rehearsals and live surgeries.ConclusionThis reproducible method shows high anatomical accuracy, realistic tissue properties, and translational effects between rehearsals and live surgery. To determine the effects on patient outcomes, future studies will compare the impact of completing a pre-operative rehearsal vs standard surgical preparation.

Dataset Information

Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores.

Publications

Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores.

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