Papers by Keyword: Green Sand

Abstract: The green sand mold with good mold properties are useful to obtain the sound cast iron castings. For example, the green sand mold with high density and uniform for compacting characteristics would be required. Molding simulation is indispensable to make a good sand mold. In recent years, the package software was released from software vendors of foundry CAE, and the demand for molding simulation is increasing. Fundamental algorithms of the green sand particulate model and the three-dimensional Discrete Element Method (DEM) were proposed. They take into consideration of the particle size distribution and the cohesion of green sand particles.In this study, the squeeze molding simulation is carried out and we execute the re-development of this method under the current computer environment. They are tried to simulate the dynamic behavior during molding and to predict the mold properties after squeeze molding. The characteristics of green sand with cohesion are reflected in the particle model called Hard-Core/Soft-Shell. The compacting behavior of squeeze molding is traced numerically, and the visualization by a three-dimensional model and comparison of dynamics molding are carried out. From the simulation with several kinds of particle distribution, it becomes clear the relationship between the void fraction and the squeeze pressure during molding. The effect of particle size distribution on sand compacting behavior is also clarified. Furthermore, the three-dimensional display of green sand with particle size distribution is very effective in the post-processing.

Abstract: The metallurgic industry, especially foundries, is a significant source of waste. For this reason, alternatives that involve reuse and recycling are necessary to minimize waste disposal in landfills and recover matter and energy. The feasibility of elaborating ceramic matrix composites with the incorporation of foundry waste was investigated in this study. Two types of residues were used to elaborate the composites. Green sand and grit blasting powder, in formulations with concentrations that ranged from 5.0 to 10.0% (m/m). The specimens were molded by uniaxial pressing, and a thermal treatment at 1000 °C was performed. The materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), particle size determination, linear retraction, water absorption, mechanical strength, leaching and solubilization. The results indicate that the incorporation of waste to the ceramic mass enables the processing of specimens with properties of industrial interest, such as mechanical strength and water absorption.

Abstract: In order to solve the nonlinear output/input problem of the capacitance method measuring the moisture content of green sand, a nonlinear compensation is added into the measurement system and the neural network is used for nonlinear rectification. Based on introducing the principle of non-linear compensation, a functional link artificial network with multi-input and single-output is constructed. In the network, the output voltage of capacitance moisture sensor is taken as the input and the moisture content of green sand is taken as the output. The data samples obtained in laboratory are used to train the network, and the dynamic rectification model is got. The experimental results show that the maximum difference and relative error of the moisture content are ±0.09% and ±1.85% after nonlinear rectification by the functional link neural network, and it is significantly better than those of the least square method.

Abstract: The research represents the actual effect of clay and core sand content on the permeability, compressive strength and hot wet tensile strength of green sand by adding clay and core sand into green sand mixture in order to simulate the actual situation of clay and core sand continuously increasing in the used sand during the foundry production. It was found that the content of clay and core sand affect the permeability, compressive strength and hot wet tensile strength of molding sand. With the content of clau and core sand increasing, the permeability of molding sand reduces and has a peak when core sand reaches certain content; the strength of molding sand is high and stable when the content of clay and core sand is below certain amount, and then decreases with the content of clay and core sand increasing. For green sand with resin bonded sand, the effect of clay on hot wet tensile strength appears a curve of “Peak shape”, while for green sand with sodium silicate bonded sand, the effect of clay and core sand on hot wet tensile strength appears “Annual Ring shape” as whose center is the coordinate’s dot.

Abstract: The green sand containing hot-box resin sand was reclaimed by the process of calcination followed by mechanical reclamation. The reclaimed sands were reused in the hot-box process. The grain size distribution, the shape factor, the clay content and the acid demand value were determined. The results show that the acid demand value of the reclaimed sand is higher than that of the base sand. Compared with the base sand, the grain size of the reclaimed sand is almost no difference. It can also be observed that the tensile strength of the molding sand is influenced by the acid demand value and clay content, but the reclaimed sand can still meet the casting process needs. In addition, the reclaimed green sand is satisfactory for hot-box process.

Abstract: Green sand casting and chill mould casting methods are representing the slow and fast cooling rates of the brass casting, respectively. The compositions of the raw material for this study were about Cu70 and Zn30, which falls under alpha (α) brass. Slow cooling rate casting shows coarse dendritric structures with large spacing between the dendrites. On the other hand, faster cooling rate casting shows finer grains with shorter dendrite spacing. The developed structure during solidification influences the properties of the cast samples. As grain size decreases, the strength of the cast brass increases; micro-porosity in the casting decreases and the tendency for the casting to fracture also decreases. However, the macro-examinations of fracture surfaces of these castings show the differences in the cast samples. Fracture surfaces of the sand cast specimen show larger dimples taking longer time to break indicating higher elongation. However, chill cast specimen shows smaller dimples and cleavage type fracture surface having higher strength and lower elongation.