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

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.

Microstructure and Phase Formation of Novel Al80Mg5Sn5Zn5X5 Light-Weight Complex Concentrated Aluminum Alloys

In this work, three novel complex concentrated aluminum alloys were developed. To investigate the unexplored region of the multicomponent phase diagrams, thermo-physical parameters and the CALPHAD method were used to understand the phase formation of the Al80Mg5Sn5Zn5Ni5, Al80Mg5Sn5Zn5Mn5, and Al80Mg5Sn5Zn5Ti5 alloys. The ingots of the alloys were manufactured by a gravity permanent mold casting process, avoiding the use of expensive, dangerous, or scarce alloying elements. The microstructural evolution as a function of the variable element (Ni, Mn, or Ti) was studied by means of different microstructural characterization techniques. The hardness and compressive strength of the as-cast alloys at room temperature were studied and correlated with the previously characterized microstructures. All the alloys showed multiphase microstructures with major α-Al dendritic matrix reinforced with secondary phases. In terms of mechanical properties, the developed alloys exhibited a high compression yield strength up to 420 MPa, high compression fracture strength up to 563 MPa, and elongation greater than 12%.

DECORATED MODELS, REPLICATION, AND ASSEMBLY LINES FOR BRONZE INDUSTRIAL PRODUCTION IN 500 b.c.e. CHINA

This article examines the earliest examples of replication of bronze objects of complicated structure in China. It uses four quadrupeds from the Freer Gallery (National Museum of Asian Art, Smithsonian Institution), the Asian Art Museum of San Francisco, the British Museum, and the Yūrinkan Museum in Kyōto as examples to illustrate the complex technology required in replicating bronzes. It provides evidence to define identical bronzes and proves that the four quadrupeds shared the same decorated model. The application of section-mold casting, spacers, clay cores, and mold section assemblage will be examined using 3D scanning, X-ray photography, computerized tomography (CT) scanning, and alloy composition analysis.

Experimental Research of Piece-Mold Casting: Gilt-Bronze Pensive Bodhisattva

We have tried the experimental research of lost-wax casting to reconstruct Gilt-Bronze Pensive Bodhisattva; preliminary and reconstruction experiment based on ancient texts. Main object to reconstruct is Korean National Treasure No.83, Gilt-Bronze Pensive Bodhisattva (Maitreya), then we measure alloy ratio and casting method based on the scientific analysis. Other impurities were removed from the base metal components(copper : tin : lead) and their ratio was set to 95.5 : 6.5 : 3 where the ratios for tin and lead were increased by 2.5% each. The piece-mold casting method was used, and piece-mold casting experiments were carried out twice in this study but supplementary research on piece-mold casting was necessary. The microstructure was confirmed to be typical cast microstructure and the component analysis result was similar to that of the prior study. Analysis of the chemical composition is confirmed to copper, tin, lead, and zinc, and the chemical composition of the matrix was 87.8%Cu-7.5%Sn-2.7%Pb-2.1%Zn, and similar to previous experimental research. Also resulted in the detection of small impurity in Zn. Analysis of the mould revealed that the mould was fabricated by adding quartz and organic matter for structural stability, fire resistance, and air permeability. We expect that our research will contribute to provide base data for advanced researches in future.

Additive Manufacturing of Textured FePrCuB Permanent Magnets

Permanent magnets based on FePrCuB were realized on a laboratory scale through additive manufacturing (laser powder bed fusion, L-PBF) and book mold casting (reference). A well-adjusted two-stage heat treatment of the as-cast/as-printed FePrCuB alloys produces hard magnetic properties without the need for subsequent powder metallurgical processing. This resulted in a coercivity of 0.67 T, remanence of 0.67 T and maximum energy density of 69.8 kJ/m3 for the printed parts. While the annealed book-mold-cast FePrCuB alloys are easy-plane permanent magnets (BMC magnet), the printed magnets are characterized by a distinct, predominantly directional microstructure that originated from the AM process and was further refined during heat treatment. Due to the higher degree of texturing, the L-PBF magnet has a 26% higher remanence compared to the identically annealed BMC magnet of the same composition.

Design of metal casting mold for ADC 12 aluminium alloy with assistance of 20 kHz ultrasonic vibration

Metal mold casting is widely used in industry because of higher accuracy than sand casting and lower cost than diecasting. Metal mold casting can yield products with complex shapes and adjustable cooling rate. In this work, designing and fabrication of 20 kHz ultrasonic assisted mold casting using 20Cr steel are studied. Some major components such as motor, heater power, melting chamber are selected and calculated. Model for heating and pouring the ADC 12 alloy is designed. Samples with and without ultrasonic vibration are investigated using 3D laser scan.

Manufacturable casting parts design with topology optimization of structural assemblies

This paper presents a design method for manufacturable casting parts based on topology optimization of structural assemblies, which considers the geometry requirement and the manufacturing constraint of die-set material cost. The problem formulation follows the previous work presented in multi-component topology optimization for stamped sheet metal assemblies (MTO-S). Based on the vector method combined with Heaviside function, the moldability constraints for casting parts is formulated. As the base structure of component is easily misidentified as an undercut structure by the moldability constraints in the structural assemblies, the component baseline is proposed to realize the automatic filtering of the “fake” undercut structures which can be extended to the parting line to obtain the form of two-mold design. Several numerical examples on compliance minimization of single-mold and two-mold casting parts are conducted to verify the validity of the proposed method. The optimized results show that there is no interior void for each component and the component manufacturability has been improved obviously. The setting of minimum-area bounding box (MABB) area constraint limits and the number of components will have a significant effect on the performance of the optimized structure. Users can achieve the desirable solution based on their actual demand by making trade-offs between the structural performance and manufacturing cost.

Effect of Egg Shell Composition on the Flexural and Hardness Properties of Epoxy Resin/ Egg Shell Particles Composite

The effect of calcined egg shell particles on the mechanical properties of epoxy resin had been studied. The egg shell was sun dried for 3 days and calcined at 800oC in an electrically fired furnace model KGVB. The calcined egg shell was ground in a locally fabricated pulverized machine and sieved using Sieve Model 567924/173281Endecotts in accordance with ASTM standard. Microwave digestion system and an inductively coupled plasma mass spectrometer (ICP-MS) were used to determine the chemical composition of the egg shell. The egg shell particles were mixed with epoxy resin to develop a composite casted by open mold casting. The flexural and hardness properties of the developed composite was determined using Universal Testing Machine model TUE-C-100, observing ASTM D790 standard and Rockwell Scale K hardness testing machine according to ASTM D785 respectively. The results showed that the calcined egg shell contained mostly CaO. Maximum flexural strength of 12MPa was observed at 25 wt. % egg shell particles. The highest hardness value of HRN 393 was observed at 20 wt. % egg shell particles. The produced composites may be applied where moderate strength is required.