scholarly journals De-Powdering Effect of Foundry Sand for Cement Casting

2021 ◽  
Vol 12 (1) ◽  
pp. 266
Author(s):  
Seungyeop Chun ◽  
Geumyeon Lee ◽  
Sujin Kim ◽  
Bora Jeong ◽  
Jeehoon Shin ◽  
...  
Keyword(s):  
3D Printing ◽  
Silica Sand ◽  
Powder Layer ◽  
Test Results ◽  
Binding Properties ◽  
Powder Bed ◽  
3D Printed ◽  
New Research ◽  
Aluminate Cement ◽  
Thermal Stability Of

With the development of the powder bed 3D printing process, sand casting can be performed with methods that are more advanced than the traditional ones, thus enabling new research on applied materials. When sand is 3D-printed with cement as a binder, its casting performance is improved and sufficient thermal stability of conventional organic and inorganic binders is ensured. In this study, to ensure high resolution and strength in a physical and simple mixture of cement and sand, the compatibility for casting was confirmed using submicron-level cement with ingredients and sizes similar to commercial sand, which is uniformly controlled at 4 µm, instead of conventional sand. To enable quick 3D printing, calcium aluminate cement, which has quick binding properties, was used for high-temperature casting. The strength up to 6 h after hydration was compared to determine the curing rate of silica, mullite, and alumina sand containing cement components. By investigating the change in strength due to heat treatment and comparing the adhesion drop test results after powder bed formation, the material containing silica sand was determined as the most suitable for powder layer 3D printing for application to the mold.

scholarly journals Effects of Post-Treatment to Improve the Surface Quality of 3D Printing Cement Mold Casting

2021 ◽  
Vol 11 (24) ◽  
pp. 11824
Author(s):  
Seung-Yeop Chun ◽  
Geumyeon Lee ◽  
Su-jin Kim ◽  
Bora Jeong ◽  
Jeehoon Shin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
3D Printing ◽  
Surface Quality ◽  
Post Treatment ◽  
Silica Sand ◽  
Gas Generation ◽  
Powder Bed ◽  
Aluminum Castings ◽  
Mold Casting ◽  
Spherical Silica

Powder bed 3D printing can be applied to sandcasting mold manufacturing to ensure high quality and economy through process innovation. In this study, refractory alumina cement was used as an aqueous binder to ensure high-temperature thermal stability to minimize the addition of organic matter to reduce gas generation. In addition, spherical silica sand, the study material, was selected to a size of 30 µm to improve the casting mold resolution. To improve the surface quality through the post-treatment process, we confirmed the change in the surface roughness of the mold depending on the surface treatment of colloidal silica and the presence or absence of heat treatment, and finally made the mold through actual casting. Changes in the surface roughness and flowability of the cast body after mold post-treatment were confirmed. For aluminum castings, the shrinkage rate and surface roughness were confirmed in a box-shaped mold via gravity casting, and the flowability of the molten metal in the mold was confirmed in a hand-shaped mold. There was a change in the roughness and porosity of the mold, owing to the post-treatment, and the influence of the surface roughness and flowability of the cast body during actual casting was confirmed.

scholarly journals Comparison between Tests and Simulations Regarding Bending Resistance of 3D Printed PLA Structures

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4371
Author(s):  
Dorin-Ioan Catana ◽  
Mihai-Alin Pop ◽  
Denisa-Iulia Brus
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Process Parameters ◽  
Bending Stress ◽  
Test Results ◽  
Printing Process ◽  
Simulation Process ◽  
Bending Resistance ◽  
3D Printed

Additive manufacturing is one of the technologies that is beginning to be used in new fields of parts production, but it is also a technology that is constantly evolving, due to the advances made by researchers and printing equipment. The paper presents how, by using the simulation process, the geometry of the 3D printed structures from PLA and PLA-Glass was optimized at the bending stress. The optimization aimed to reduce the consumption of filament (material) simultaneously with an increase in the bending resistance. In addition, this paper demonstrates that the simulation process can only be applied with good results to 3D printed structures when their mechanical properties are known. The inconsistency of printing process parameters makes the 3D printed structures not homogeneous and, consequently, the occurrence of errors between the test results and those of simulations become natural and acceptable. The mechanical properties depend on the values of the printing process parameters and the printing equipment because, in the case of 3D printing, it is necessary for each combination of parameters to determine their mechanical properties through specific tests.

scholarly journals Thermal Stability of Type II Modifications Inscribed by Femtosecond Laser in a Fiber Drawn from a 3D Printed Preform

2021 ◽  
Vol 11 (2) ◽  
pp. 600
Author(s):  
Yitao Wang ◽  
Shuen Wei ◽  
Maxime Cavillon ◽  
Benjamin Sapaly ◽  
Bertrand Poumellec ◽  
...  
Keyword(s):  
Thermal Stability ◽  
3D Printing ◽  
Femtosecond Laser ◽  
Optical Fibers ◽  
Thermal Performance ◽  
Single Mode ◽  
Type Ii ◽  
Fs Laser ◽  
3D Printed ◽  
Thermal Stability Of

Fiber drawing from a 3D printed perform was recently discussed to go beyond the limitations of conventional optical fiber manufacturing in terms of structure and materials. In this work, the photosensitivity of silica optical fibers to femtosecond laser light, and fabricated by 3D printing a preform, is investigated. The writing kinetics and the thermal performance of Type II modifications are studied by varying the laser pulse energy and investigating the birefringence response of the femtosecond (fs)-laser written structures. Compared with a conventional telecom single mode fiber (SMF28), the fiber made by 3D printing is found to have similar writing kinetics and thermal performance. Additionally, the thermal stability of the imprinted fs-laser induced nanostructures is investigated based on the Rayleigh–Plesset equation, describing a model of nanopores dissolution underpinning Type II modifications with thermal annealing.

Method for characterization and enhancement of 3D printing by binder jetting applied to the textures quality

2017 ◽  
Vol 37 (2) ◽  
pp. 162-169 ◽  
Author(s):  
Julien Gardan
Keyword(s):  
Image Processing ◽  
3D Printing ◽  
Computer Aided Design ◽  
Product Life Cycle ◽  
Content Type ◽  
Powder Bed ◽  
3D Printed ◽  
Aided Design ◽  
Binder Jetting

Purpose This paper aims to present a technical approach to evaluate the quality of textures obtained by an inkjet during binder jetting in 3D printing on a powder bed through contours detection to improve the quality of the surface printed according to the result of the assembly between the inkjet and a granular product. Design/methodology/approach The manufacturing process is based on the use of computer-aided design and a 3D printer via binder jetting. Image processing measures the edge deviation of a texture on the granular surface with the possibility of implementing a correction in an active assembly through a “design for manufacturing” (DFM) approach. Example application is presented through first tests. Findings This approach observes a shape alteration of the printed image on a 3D printed product, and the work used the image processing method to improve the model according to the DFM approach. Originality/value This paper introduces a solution for improving the texture quality on 3D printed products realized via binder jetting. The DFM approach proposes an active assembly by compensating the print errors in upstream of a product life cycle.

3D printing of metallic micro-gears for micro-fluidic applications

2021 ◽  
Author(s):  
C. Wang ◽  
S. Chandra ◽  
X. P. Tan ◽  
S. B. Tor
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Stainless Steel 316L ◽  
Promising Alternative ◽  
Powder Bed ◽  
Micro Scale ◽  
Direct Fabrication ◽  
Custom Made ◽  
Fluidic Devices ◽  
3D Printed

Micro-fluidic devices are essential to handle fluids on the micro-meter scale (micro-scale), making them crucial to biomedical applications, where micro-gear is the key component for active fluid mixing. Rapid and direct fabrication of micro-gears is preferred because they are usually custom-made to specific applications and iterative design is needed. However, conventional manufacturing (CM) techniques for micro-fluidic devices are labor-intensive and time-consuming as multiple steps are required. Three-dimensional (3D) printing, or formally known as additive manufacturing (AM) offers a promising alternative over CM techniques in producing near-net shape complex geometries, given the micro-scale fabrication process. In this work, two types of powder-bed fusion (PBF) AM techniques, namely laser-PBF (L-PBF) and electron beam-PBF (EB-PBF) are used to benchmark 3D-printed micro-gears from stainless steel 316L micro-granular powders. Results showcase the preeminence of L-PBF over EB-PBF in generating distinguishable micro-scale features on gear profiles and superior micro-hardness in mechanical property. Overall, PBF metal AM shows significant promise in advancing the otherwise tedious state of CM for micro-gears.

scholarly journals Finite Element Modeling of 3D Printed Parts With Defects

2021 ◽  
Author(s):  
Geethanjali Chandramouli
Keyword(s):  
Finite Element ◽  
3D Printing ◽  
Failure Analysis ◽  
Mechanical Characterization ◽  
Failure Strain ◽  
Progressive Failure ◽  
Experimental Result ◽  
Test Results ◽  
Progressive Failure Analysis ◽  
3D Printed

To manufacture a component, one first needs to assess its structural design performance, damage tolerance, and service experience, and validate them with pertinent test results. Finite Element (FE) modeling can predict mechanical performance, save time and cost by limiting required structural testing. 3D printing is a layer-by-layer manufacturing technology that has been widely used for rapid prototyping applications in product design and development. Recently, there has been a move towards manufacturing functional products using 3D printing, which requires materials mechanical characterization and simulation. Mechanical characterization testing results are available for 3D printed ASTM D638 tensile coupons without defects, i.e. tension along (0°) and transverse (90°) to the printing direction, and a quasiisotropic stacking sequence. In addition, tensile test results of a quasi-isotropic coupon with intentional defects are also available. In this project, FE models of the coupons are created to obtain their tensile strength, modulus, and failure strain. First ply, last ply failure and stiffness reduction iterative approach have been implemented on a 2D shell model. MSC Software is used to simulate the analyses due to its ease of use for composites using 2d shell elements. This simulation is then extended to predict strength and stiffness of a quasi-isotropic coupon with defects. The analysis is also extended to implement progressive failure analysis to predict the ultimate strength of the laminate. For coupons without defects, FE models estimated test results of stiffness and strength within 1% error, while the error for estimating failure strain is higher. For coupons with defects, the error in calculating stiffness and strength is below 8%, while it is higher for failure strain. Although the stress-strain curve from FE simulation looks similar to experimental result, it is found that progressive failure analysis is necessary for obtaining failure strain values with acceptable error percentage.

scholarly journals 3D-printed swab with cover for precision diagnosis

2022 ◽  
Vol 33 (1) ◽  
Author(s):  
Fan Huang ◽  
Kewei Song ◽  
Yue Jiang ◽  
Kayo Hirose ◽  
Shinjiro Umezu
Keyword(s):  
3D Printing ◽  
Medical Personnel ◽  
Test Results ◽  
Printing Technology ◽  
Medical Supply ◽  
3D Printing Technology ◽  
3D Printed ◽  
Nasal Secretions ◽  
Series Of Experiments ◽  
Pcr Test

AbstractThe collection capacity of common nasopharyngeal swabs and irregularities of medical personnel limit the accuracy of PCR testing. This study describes a newly designed 3D-printed swab that is combined with a 3D-printed cover to prevent the extraction of undesired nasal secretions. This swab improved the accuracy of PCR test results. The results of a series of experiments showed that, because of the mucus extraction effect, 3D-printed swabs can replace ordinary cotton swabs. The crisis of the worldwide medical supply shortage can be ameliorated to a certain extent by applying 3D printing technology.

scholarly journals Integrated Design Approaches for 3D Printed Tissue Scaffolds: Review and Outlook

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2355 ◽  
Author(s):  
Egan
Keyword(s):  
3D Printing ◽  
Material Selection ◽  
Integrated Design ◽  
Simulation Models ◽  
Tissue Scaffolds ◽  
Mechanical Stiffness ◽  
Tissue Scaffold ◽  
Trade Offs ◽  
3D Printed ◽  
New Research

Emerging 3D printing technologies are enabling the fabrication of complex scaffold structures for diverse medical applications. 3D printing allows controlled material placement for configuring porous tissue scaffolds with tailored properties for desired mechanical stiffness, nutrient transport, and biological growth. However, tuning tissue scaffold functionality requires navigation of a complex design space with numerous trade-offs that require multidisciplinary assessment. Integrated design approaches that encourage iteration and consideration of diverse processes including design configuration, material selection, and simulation models provide a basis for improving design performance. In this review, recent advances in design, fabrication, and assessment of 3D printed tissue scaffolds are investigated with a focus on bone tissue engineering. Bone healing and fusion are examples that demonstrate the needs of integrated design approaches in leveraging new materials and 3D printing processes for specified clinical applications. Current challenges for integrated design are outlined and emphasize directions where new research may lead to significant improvements in personalized medicine and emerging areas in healthcare.

Computation of hydrodynamic and capillary phenomena in binder jet 3D printing

2021 ◽  
pp. 1-51
Author(s):  
Joshua Wagner ◽  
C. Fred Higgs
Keyword(s):  
3D Printing ◽  
Contact Angles ◽  
Droplet Impact ◽  
Powder Layer ◽  
Immersed Boundary ◽  
Powder Bed ◽  
Capillary Phenomena ◽  
Three Phase ◽  
Air Interfaces ◽  
Hydrodynamic Effects

Abstract The fundamental operation in binder jet 3D printing is the deposition of liquid binder into a powder layer to selectively bond particles together. Upon droplet impact, the binder spreads into the powder bed forming a bound network of wetted particles called a primitive. A computational fluid dynamics framework is proposed to directly simulate the capillary and hydrodynamic effects of the interfacial flow that is responsible for primitive formation. The computational model uses the volume-of-fluid method for capturing dynamic binder-air interfaces, and the immersed boundary method is adopted to include particle geometries on numerical Cartesian grids. Three-phase contact angles are prescribed through an interface extension algorithm. Binder droplet impact on powder beds of varying contact angle are simulated. Furthermore, the numerical model is used to simulate liquid bridges connecting binary and ternary particle systems, and the resulting capillary and hydrodynamic forces are validated by comparison with published experimental and theoretical model results.

scholarly journals Finite Element Modeling of 3D Printed Parts With Defects

2021 ◽  
Author(s):  
Geethanjali Chandramouli
Keyword(s):  
Finite Element ◽  
3D Printing ◽  
Failure Analysis ◽  
Mechanical Characterization ◽  
Failure Strain ◽  
Progressive Failure ◽  
Experimental Result ◽  
Test Results ◽  
Progressive Failure Analysis ◽  
3D Printed

To manufacture a component, one first needs to assess its structural design performance, damage tolerance, and service experience, and validate them with pertinent test results. Finite Element (FE) modeling can predict mechanical performance, save time and cost by limiting required structural testing. 3D printing is a layer-by-layer manufacturing technology that has been widely used for rapid prototyping applications in product design and development. Recently, there has been a move towards manufacturing functional products using 3D printing, which requires materials mechanical characterization and simulation. Mechanical characterization testing results are available for 3D printed ASTM D638 tensile coupons without defects, i.e. tension along (0°) and transverse (90°) to the printing direction, and a quasiisotropic stacking sequence. In addition, tensile test results of a quasi-isotropic coupon with intentional defects are also available. In this project, FE models of the coupons are created to obtain their tensile strength, modulus, and failure strain. First ply, last ply failure and stiffness reduction iterative approach have been implemented on a 2D shell model. MSC Software is used to simulate the analyses due to its ease of use for composites using 2d shell elements. This simulation is then extended to predict strength and stiffness of a quasi-isotropic coupon with defects. The analysis is also extended to implement progressive failure analysis to predict the ultimate strength of the laminate. For coupons without defects, FE models estimated test results of stiffness and strength within 1% error, while the error for estimating failure strain is higher. For coupons with defects, the error in calculating stiffness and strength is below 8%, while it is higher for failure strain. Although the stress-strain curve from FE simulation looks similar to experimental result, it is found that progressive failure analysis is necessary for obtaining failure strain values with acceptable error percentage.

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