Papers by Keyword: Mold Filling

Abstract: Centrifugal casting process is one of the potential manufacturing techniques used for producing functionally graded materials viz., composite materials or metallic materials which have high differences of density among constituents. In this process, the fluid flow plays a major role and understanding the complex flow process is a must for the production of defect-free castings. Since the mold spins at a high velocity and the mold wall being opaque, it is impossible to visualise the flow patterns in real time. Hence, in the present work, the commercial CFD code FLOW-3DTM, has been used to simulate the mold filling sequence for a simple hollow cylindrical casting during vertical centrifugal casting process. Effect of various spinning velocities on the fill pattern during vertical centrifugal casting process is being investigated.

Abstract: The calibre of low pressure casting (LPC) process in meeting the demands for improved quality and aesthetics for thin walled components has been widely accepted in casting industries. In spite of numerous advantages, the process is still being used very less to its potential. The basic reason has been the difficulty in determining various processing parameters associated which can be circumvented effectively by numerical simulation. In the present work, the commercial CFD code FLOW 3D^TM, has been used to simulate the mould filling and solidification during the LPC process.

Abstract: With the development of computer technology, casting simulation plays an increasingly important role in foundry production. VOF (Volume of Fluid) method which tracks free surfaces is widely used in casting simulation because it is simple to solve and easy to achieve. However, in the last stage of mold filling process, the solution speed of VOF method is very slow because the space to fill becomes smaller. To solve this problem, interpolation formula is applied to the calculation of temperature field and an interpolation method to calculate the last part of temperature field in mold filling process is presented in this paper. The solution is to calculate temperature field of unfilled grids based on the temperature filed of filled grids at the last stage of filling process. Comparison between the results of interpolation method and theoretical calculation illustrates the rationality of the interpolation temperature field in this paper. Numerical simulations of actual castings indicate that the interpolation method can greatly improve the speed of getting temperature field under a certain accuracy. This paper has important implications to the calculation of numerical simulation in mold filling process.

Abstract: The casting and solidification process of the bimetallic composite pipe were simulated by ProCAST software aiming at the misrun defect in the pipe. The causes of defect were analyzed from the factors of the pouring temperature, pouring time, preheating temperature of mold and the height of sprue. Reasonable improvements were presented based on the simulation results. Industrial tests showed that misrun defect disappeared after the process was improved, which in turn verified the effectiveness and reliability of simulation results.

Abstract: Thixoforming is a new forming technology which has been studied by many researchers during the last years. Mold filling is one of the most important steps for casting engineers which should be controlled to have a sound part. In the semisolid alloy forming die design, viscosity variations during forming and temperature decreasing, solid fraction plus globularity are the main parameters which affect final product. In this study, a stepped die was designed and some billets in different weights were injected into the die. This process helps to characterize the flow pattern during mold filling. The effect of two phase flow was also studied by microstructural investigating. Numerical simulation is the second method which is used in this study. The ProCast software was used to indicate the flow pattern of the fluid in the mold. Some comparisons were also done to show that this software is a suitable simulating software to predict the flow behavior of semisolid alloys. Also, the step casting method shows the exact pattern of flow in different parts of mold and is a reliable method for researchers to investigate the fluid pattern.

Abstract: Mold filling and solidification of molten steel for 750mm×450mm×300mm continuous casting mold of single SEN and double SEN are simulated by using CFD commercial code Flow-3d. The distributing diagrams of velocity field and temperature field and the location and shape diagrams of free-surface during mold filling process are obtained. Influences of single SEN model and double SEN model on velocity field and solidification are analyzed. It is found that double SEN model can lighten circumfluence intensity at the upper of mold, quicken solidification speed of steel liquid in the mold, which is favorable to improving the quality of billet and enhancing pull speed.

Abstract: The numerical simulations of mold filling and solidification process for the A380 aluminum alloy were done by the supposed mathematical model. The casting defects in the process of mold filling and solidification were predicted by the result of the casting simulation. The casting defects of simulation are well compared with the practice. Some measures presented were improved for the existing technological process.

Abstract: Magnesium alloys are increasingly used in automotive, aeronautic and electronic applications to produce high performance, light weight parts. In the thixomolding process the semisolid slurry is injected into a mold at controlled temperature such that the melt has specific flow behavior. This allows the fabrication of near net shape components with controlled microstructure and good mechanical properties. The numerical modeling of such applications presents unusual challenges for both the physical modeling and the solution algorithm. This paper presents 3D solutions of the injection molding of semi-solid AZ91 magnesium alloys. The methodology deals with the shear thinning, temperature dependent viscosity behavior and is able to accurately solve the high velocity flows encountered during semi-solid magnesium molding. The approach is applied to the injection of a tensile bar and the results compared with experimental data. The numerical solutions indicate that the material forms a jet at the exit of the gate and a swirling flow forms as the material advances along the first larger diameter section. The wall regions are filled first, leaving a void inside. This agrees very well with the experimental observation.

Abstract: In the numerical simulation of mold filling process, the calculation efficiency has been a key point for practical applications due to the complexity and thin-section of die castings. In current research work, a fractional step method was applied in the solution of the unsteady Navier-Stokes equations, which can be implemented with a single solution to the momentum/pressure equations at each time step. This method may avoid the decrease in efficiency induced by iteration. A water analog system was designed and developed to simulate the die casting process. The flow patterns were recorded by a high speed camera with a capturing rate of 500 frames per second. The simulation results were consistent with the experimental ones. Besides, the fluid flow patterns of several components were simulated by the fractional step and VOF algorithm, and the SOLA-VOF algorithm respectively. The simulation results showed that the combination of the fractional step method and VOF method can improve the computational efficiency to some extent in numerical simulation of mold filling process.

Abstract: Techniques of numerical simulation on mold filling process of casting are investigated in this paper. The mathematical model is formed on the ground of some selected theories in computational fluid dynamics (CFD), Numerical Heat Transfer (NHT) and computational methods to interfacial tracking. The discrete solution to the governing equations appeals to Finite Volume Method (FVM) on structured mesh. As for viscous turbulence flow and multiphase fluid flow in mold filling, engineering turbulence model and Volume of Fluid (VOF) method are adopted in the algorithms, respectively. As a debut, the general-purpose CFD software is used to establish the practicable mechanical model for the simulation. By means of numerical simulation, variation and distribution of velocity, temperature, stress and configuration of casting, etc. with respect to time and space in the filling process can be quantitatively analysed in detail, which is helpful for engineers to optimize their design of technics with less time and less cost and is meaningful to provide the subsequent simulation, solidification process of casting, with initial conditions.