Optimum Runner Design for Die Casting Using CFD Simulations and Verification With Water-Model Experiments

2014 ◽  
Author(s):  
Ken’ichi Kanazawa ◽  
Ken’ichi Yano ◽  
Jun’ichi Ogura ◽  
Yasunori Nemoto
Keyword(s):  
Molten Metal ◽  
Die Casting ◽  
Air Entrainment ◽  
Optimization Method ◽  
Water Model ◽  
Cfd Simulations ◽  
Mathematical Functions ◽  
Model Experiments ◽  
Runner Design ◽  
Pressure Die Casting

This study aimed to optimize the design of a runner for high-pressure die casting (HPDC) using computational fluid dynamics (CFD) simulations, and to verify the effectiveness of the runner with water-model experiments. A runner is a part of the flow path through which molten metal enters a product part. As a design problem, we sought to optimize the shape of the runner to minimize air entrainment in the runner and align the flow of molten metal after it passed through the runner. The problem was solved using our proposed nonparametric shape optimization method. The method is based on a genetic algorithm (GA), and directly treats a geometric shape that is comprised of several curves as an individual of a GA in the form of a set of mathematical functions. In addition, the crossover, which is one of the genetic operations, is defined as a weighted summation of two parent curves. Thus, the optimization method can generate optimized shapes with a lot of flexibility. The effectiveness of the optimized shape of the runner was demonstrated with both CFD simulations and water-model experiments using a visualization device for HPDC.

On the Critical Plunger Speed and Three-Dimensional Effects in High-Pressure Die Casting Injection Chambers

2003 ◽  
Vol 125 (3) ◽  
pp. 529-537 ◽  
Author(s):  
J. Lo´pez ◽  
F. Faura ◽  
J. Herna´ndez ◽  
P. Go´mez
Keyword(s):  
Molten Metal ◽  
Cross Section ◽  
Die Casting ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Water Model ◽  
Two Dimensional ◽  
Shallow Water Model ◽  
One Dimensional ◽  
Pressure Die Casting

During the initial slow stage of the injection process in high-pressure die casting machines with horizontal cold chamber, a plunger pushes the molten metal which partially fills the injection chamber, causing the formation of a gravity wave. The evolution of the wave surface profile, which depends on the plunger acceleration law, may trap air in the molten metal, causing porosity when the metal solidifies. In this work, a one-dimensional shallow-water model, which is solved numerically using the method of characteristics, and a three-dimensional numerical model, based on a finite element formulation and the volume of fluid (VOF) method for treating the free surface, are used to analyze the flow of molten metal in an injection chamber of circular cross section. The results for the evolution of the free surface obtained from both models for different plunger motion laws and initial filling fractions of the injection chamber were in good agreement for broad ranges of operating conditions. The existence of a critical plunger speed, above which the reflection of the wave of molten metal against the chamber ceiling might appreciably increase air entrapment effects, is investigated. The results for the wave profiles in chambers of circular cross section are compared with those obtained in an equivalent two-dimensional configuration of the injection chamber, for which the shallow-water model is solved analytically. It is shown how the results obtained by applying the one-dimensional model to a two-dimensional chamber configuration can be used to reproduce, with an acceptable degree of accuracy, the salient characteristics of the flow of molten metal in a real injection chamber of circular cross section.

Analysis of Mass Transfer Process in the Pore Free Technique

1995 ◽  
Vol 117 (2) ◽  
pp. 215-219 ◽  
Author(s):  
Genick Bar-Meir
Keyword(s):  
Mass Transfer ◽  
Dimensionless Parameter ◽  
Die Casting ◽  
Air Entrainment ◽  
Mass Transfer Process ◽  
Critical Value ◽  
First Case ◽  
Pressure Die Casting ◽  
The Relationship ◽  
Transfer Mechanisms

Air entrainment is one of the most significant problems in pressure die casting. A possible solution is to use the Pore Free technique. In this technique an oxygen is introduced into the die to react with the liquid metal. The vacuum created by the reaction reduces the porosity. The life span of the mold is augmented by the reduction of the pressure during the process. In some cases the Pore Free technique yields acceptable results, i.e., low porosity, while in other cases the results are not satisfactory. These differing results can be explained by an analysis of the mechanisms involved. A simple model is proposed based on conservation laws that describes the relationship between mass transfer mechanisms and pressure deviation. The model indicates that there is a critical dimensionless parameter above which the pressure is decreased and below which the pressure is increased. In the first case, when the parameter exceeds the critical value, the technique is useful. In the second case, when the parameter is less than the critical value, introducing oxygen does not greatly reduce the porosity. The analysis demonstrates that the Pore Free and vacuum venting techniques account for two different extremes. The first case is when the flow is orderly throughout the chamber in which vacuum venting can produce acceptable results. The second case is when the flow is turbulent and the Pore Free technique is the better choice.

Analysis of the Flow in a High-Pressure Die Casting Injection Chamber

2003 ◽  
Vol 125 (2) ◽  
pp. 315-324 ◽  
Author(s):  
J. Herna´ndez ◽  
J. Lo´pez ◽  
F. Faura ◽  
P. Go´mez
Keyword(s):  
Shallow Water ◽  
Die Casting ◽  
Operating Conditions ◽  
Water Model ◽  
Accurate Estimation ◽  
Viscous Effects ◽  
Filling Fraction ◽  
Filling Time ◽  
Entrapped Air ◽  
Pressure Die Casting

The flow in the injection chamber of pressure die casting machines is analyzed using a model based on the shallow-water approximation which takes into account the effects of wave reflection against the end wall of the chamber. The governing equations are solved numerically using the method of characteristics and a finite difference grid based on the inverse marching method. The results of the model for wave profiles, volume of air remaining in the injection chamber at the instant at which the molten metal reaches the gate to the die cavity, and optimum values of the parameters characterizing the law of plunger motion, are compared with the numerical results obtained from a finite element code, which solves the two-dimensional momentum and mass conservation equations, taking into account nonhydrostatic and viscous effects. We found that, although the shallow-water model does not provide a very accurate estimation of the mass of entrapped air in the injection chamber for certain ranges of working conditions, it does describe reasonably well the influence of the acceleration parameters and the initial filling fraction on the entrapped air mass, and can be of help in selecting operating conditions that reduce air entrapment while keeping the injection chamber filling time as low as possible.

Pressure Die Casting: A Model of Vacuum Pumping

1996 ◽  
Vol 118 (2) ◽  
pp. 259-265 ◽  
Author(s):  
G. Bar-Meir ◽  
E. R. G. Eckert ◽  
R. J. Goldstein
Keyword(s):  
Elastic Moduli ◽  
Die Casting ◽  
Total Porosity ◽  
Air Entrainment ◽  
Pressure Variation ◽  
Filling Time ◽  
Cavity Filling ◽  
Pressure Die Casting ◽  
The Relationship ◽  
Residual Air

Multifunctional characteristics of die casting parts are significantly compromised by the presence of voids, which can result in a substantial decrease in the elastic moduli and thermal conductivity. Gas/air porosity constitutes a large part of the total porosity. To reduce the porosity due to the gas/air entrainment, a vacuum can be applied to remove the residual air in the die. In some cases vacuum castings have low porosity, while in other cases the results are not satisfactory. These differing results can be explained in some instances by an analysis of the vent area. A simple model is proposed based on conservation laws which describes the relationship between vent area and pressure variation in the die. The analysis of vacuum venting indicates that there is a critical/optimum vent area below which the ventilation is poor and above which the resistance to the air flow is minimal. The model yields a simple equation to select the optimum area which is a function of the duct resistance, the evacuated volume, and the filling time. This result should be useful to the design engineer. The result also provides a tool to “measure” the vent size for numerical simulations of the cavity filling, taking into account the compressibility of the gas.

Characterization of Magnesium Automotive Components Produced by Super-Vacuum Die Casting Process

2009 ◽  
Vol 618-619 ◽  
pp. 381-386 ◽  
Author(s):  
K. Sadayappan ◽  
W. Kasprzak ◽  
Zach Brown ◽  
L. Quimet ◽  
Alan A. Luo
Keyword(s):  
Die Casting ◽  
Casting Process ◽  
Air Entrainment ◽  
Automotive Components ◽  
Vacuum Die Casting ◽  
Heat Treated ◽  
Conventional Heat Treatment ◽  
Die Casting Process ◽  
Rapidly Solidified ◽  
Pressure Die Casting

Magnesium automotive components are currently produced by high pressure die casting. These castings cannot be heat-treated to improve the strength and ductility mainly due to the casting imperfections such as porosity and inclusions created by the air entrainment during the turbulent mold filing. These imperfections also prevent magnesium components to be used for highly stressed body components. Efforts were made to produce high integrity magnesium castings through a Super-Vacuum Die Casting process. The AZ91D castings were found to have very low porosity and can be heat-treated without blisters. The tensile properties of the castings were satisfactory. The mechanical properties and thermal analysis indicate that the conventional heat treatment procedure needs to be optimized for such thin sectioned and rapidly solidified castings which have very fine microstructures.

scholarly journals Molten metal velocities and gas pressures in die cavity of commercial aluminum pressure die-casting.

1988 ◽  
Vol 38 (3) ◽  
pp. 129-133 ◽  
Author(s):  
Yoshiaki YAMAMOTO ◽  
Yasushi IWATA ◽  
Katsutoshi TOZAWA ◽  
Motoyuki NAKAMURA
Keyword(s):  
Molten Metal ◽  
Die Casting ◽  
Pressure Die Casting ◽  
Gas Pressures

scholarly journals Analysis and Optimisation of High Pressure Die Casting Parameters to Achieve Six Sigma Quality Product Using Numerical Simulation Approach

2021 ◽  
Vol 11 (1) ◽  
pp. 97-109
Author(s):  
Suraj R. Marathe ◽  
Dr. Carmo E. Quadros
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
Molten Metal ◽  
Die Casting ◽  
Injection Pressure ◽  
Simulation Software ◽  
Holding Time ◽  
Simulation Approach ◽  
High Pressure Die Casting ◽  
Pressure Die Casting

A numerical simulation approach is proposed to predict the optimal parameter setting during high pressure die casting. The contribution from the optimal parameters, the temperature, showed more influence on the casting quality than the other parameters. This study’s outcome was beneficial for finding the solution for casting defects that occurs due to incorrect setting of process parameters in die casting. Thus, a combination of numerical optimisation techniques and casting simulation serves as a tool to improve the casting product quality in die casting industries. This paper aims to analyse and optimise critical parameters like injection pressure, molten metal temperature, holding time, and plunger velocity, contributing to the defects. In this research paper, an effort has been made to give optimal pressure, temperature, holding time, and plunger velocity parameters using ProCAST simulation software that uses finite element analysis technology. Numerical analysis for optimising the parameters by varying the temperature of molten metal, injection pressure, holding time, and plunger velocity,  concerning solidification time at hot spots, is an essential parameter for studying the defect analysis in the simulated model.

scholarly journals Optimization of Runner Design in Pressure Die Casting

2017 ◽  
Vol V6 (03) ◽  
Author(s):  
Nair Akhil K. Raveendran ◽  
Prof. Amol N. Patil ◽  
Keyword(s):  
Die Casting ◽  
Runner Design ◽  
Pressure Die Casting

Optimization of Plunger Injection Input for Die Casting Process

2020 ◽  
Author(s):  
Song Qi ◽  
Yuto Takagi ◽  
Ken'ichi Yano ◽  
Tadao Kondo ◽  
Naoto Murakami ◽  
...  
Keyword(s):  
Molten Metal ◽  
Die Casting ◽  
Casting Process ◽  
Air Entrainment ◽  
Control Input ◽  
Casting Defects ◽  
Velocity Control ◽  
Skilled Workers ◽  
Die Casting Process ◽  
Optimum Velocity

Abstract Die casting is adequate for mass production and has the advantage of being able to yield a complicated shape accurately. However, casting defects caused by plunger movement remain a problem. Velocity control of the plunger is very effective to avoid casting defects. Velocity control input is manually conducted by skilled workers because the analysis of molten metal is very difficult, and injection molding is performed at places in the mold where it is invisible. In this paper, Quid behavior and the amount of air entrainment caused by the movement of the die casting plunger are analyzed using computational Quid dynamics (CFD). The optimum velocity control input of the die casting plunger was calculated in order to reduce air entrainment and molten metal forerunning to prevent the occurrence of defects in the die casting product. Optimization was performed by a Genetic algorithm incorporating CFD simulator.

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