Mold Filling Research Articles

Observation of Air Entrapment during Mold Filling of Die Casting Using Water Model Experiment for Mold Filling Simulation

Observation of Air Entrapment during Mold Filling of Die Casting Using Water Model Experiment for Mold Filling Simulation

Assessment of Mold Filling Rate Influence on Amount of Oxide Films in Castings by Numerical Simulation

The influence of the mold filling rate on the content of oxide films in aluminum alloy castings is considered. The existing methods for estimating the probability of formation and entrainment of oxide films in the bulk of the liquid, which are associated with surface disturbances during the melt flow through the channels of the mold, are analyzed. A criterion for estimating oxide impurities in the melt using numerical process modeling is proposed. A comparative analysis of the results of numerical simulation with the data of practical experiments obtained by M. V. Sharov and N. M. Galdin was performed. This comparative analysis and experience in the development of technological processes for shaped castings showed the possibility of using the criterion in numerical modeling.

Effects of Reduced Pressure, Casting Design and Heat Transfer Resistance of Liquid Resin on Mold Filling in Expendable Pattern Casting Process of Aluminum Alloy

Effects of Reduced Pressure, Casting Design and Heat Transfer Resistance of Liquid Resin on Mold Filling in Expendable Pattern Casting Process of Aluminum Alloy

Mould fill time sensitivity analysis using isothermal mould filling simulations for applications in liquid composite moulding processes

Development of effective injection strategy constituting injection gates and air vents to obtain reduced mould fill time without dry spots are the primary requirements to develop mould system for an application using Liquid Composite Moulding (LCM) processes. Recent days, virtual simulation becomes promising tool in comparison to trial and error experiments due to its costing factor and timely iterations. This work demonstrates the possibility of Ansys Fluent commercial simulator to perform porous flow isothermal mould filling simulations and to quantify the sensitivity of mould fill time and flow front progression with respect to variations in process and raw material parameters. A rectangular mould of dimension 1 m × 0.5 m with an injection strategy of single point gate with 10 mm diameter and single point air vent of diameter 10 mm was used as a domain for isothermal mould filling. The sensitivity of mould fill time and flow front pattern were evaluated by varying inlet velocity, resin viscosity and orthotropic reinforcement mat permeability. From the results, it was found that the mould fill time decreases with increasing velocity, lesser viscosities and more porous preforms. Also, in all case studies, the mould fill pattern ends at the air vent position ensuring there are no dry spots formed.

Measurement of Metal Velocity in Sand Casting during Mold Filling

Melt turbulence during mold filling is detrimental to the quality of sand castings. In this research study, the authors present a novel method of embedding Internet of Things (IoT) sensors to monitor real-time melt flow velocity in sand molds during metal casting. Cavities are incorporated in sand molds to position the sensors with precise registration. Capacitive and magnetic sensors are embedded in the cavities where melt flow velocity is calculated by using an oscillator, the frequency of which is sensitive to changes in the close field permittivity, and change in magnetic flux, respectively. Their efficiency is investigated by integrating the sensors into 3D sand-printing (3DSP) molds for conical-helix and straight sprue configurations to measure flow velocities for aluminum alloy 319. Experimental melt flow velocities are within 5% of estimations from computational simulations. A major benefit of 3DSP is the geometrical freedom for complex gating systems necessary to reduce turbulence and access to mold volume for sensor integration during 3DSP processing. Findings from this study establish the opportunity of embedding IoT sensors in sand molds to monitor metal velocity in order to validate simulation results (2–5% error), compare gating systems performance, and improve foundry practice of manual pouring as a quality control system.

Mathematical Modelling of the Initial Mold Filling with Utilization of an Angled Runner

The flow pattern plays a crucial role in the uphill teeming process. The non-metallic inclusion generation due to interaction with the mold flux is believed to be influenced by the flow pattern. In this study, a three-dimensional mathematical model of the filling of a gating system for 10, 20, and 30 degrees angled runners was used to predict the fluid flow characteristics. Moreover, a mathematical model with a horizontal runner was applied as a reference. The predictions indicate that the angled-runner-design decreases the hump height during the initial filling stage, which results in less entrapment of mold flux into the mold. Nevertheless, increasing the angle of runner can result in a lower hump height, while the 30 degree angled runner gives a much more stable increase of the hump height during the initial filling stage. Besides CFD calculations, some thermodynamic calculations are taken into account for the chemical reactions between liquid steel and gas. The results show that the bubble shrinks due to the fact that N and O are dissolved into steel. The present findings strongly suggest that changing the horizontal runner to an angled runner would be an effective means of reducing flow unevenness during the initial filling of ingots, if the added steel losses are deemed acceptable.

Estimation of Mold Filling Ability and Volume Deficit Characteristics of Cast Al-Si Alloys

Estimation of Mold Filling Ability and Volume Deficit Characteristics of Cast Al-Si Alloys

Effect of Molten Metal Temperature on Mold Filling in Evaporative Pattern Casting

The mold filling rate during evaporative pattern casting was measured in a wide range of molten metal temperatures from 800 to 1450 °C. A polystyrene columnar foam was used as the foamed pattern, and bottom pouring was applied to design the casting. Tin alloy, copper alloy, and cast iron were used as molten metals to vary the molten metal temperature. The mold filling rate increased with increasing molten metal temperature at relatively lower temperatures. In contrast, the mold filling rate decreased with increasing molten metal temperature at high temperatures. These phenomena were verified by in situ observation.

Method for the Investigation of Mold Filling in the Fiber Injection Molding Process Based on Image Processing

Fiber Injection Molding is an innovative process for manufacturing 3D fiber formed parts. Within the process fibers are injected in a special mold through a movable nozzle by an air stream. This process allows a resource efficient production of near net-shape long fiber-preforms without cutting excess. For the properties of the preforms the mold filling is decisive, but current state of the art lacks methods to monitor mold filling online. In this paper a system for monitoring the mold filling based on image processing methods is presented. Therefor a camera and back-lighting has been integrated into a fiber injection mold. The detected filling level and fiber distribution is passed to the PLC of the fiber injection molding machine, which allows the operator to monitor the current mold filling state by means of a visual display. The image processing approach consists of preprocessing, binarization and segmentation. For the preprocessing and binarization several methods including a k-means algorithm, the Otsu thresholding method and a convolutional artificial neural network have been implemented and evaluated. Additionally the illumination of the mold has been investigated and found to have a very large influence on the quality of the results of all investigated methods. The results of the binarization are evaluated on the basis of ground truth images, where an absolute difference between labeled and binarized images is formed and the number of misinterpreted pixels is counted. Among the investigated methods, the method based on the Otsu threshold has been found to be the most efficient with regard to the achievable performance as well as to the correct detection of the current filling. The investigated approach allows the acquisition of more data about the mold filling process to improve models.

Effects of Reduced Pressure, Casting Design and Heat Transfer Resistance of Liquid Resin on Mold Filling in Expendable Pattern Casting Process of Aluminum Alloy

Effects of Reduced Pressure, Casting Design and Heat Transfer Resistance of Liquid Resin on Mold Filling in Expendable Pattern Casting Process of Aluminum Alloy

Shear Modification Mapping within Injection Moulded Product through Mould Filling Simulation and Molecular Degradation Assessment

Abstract This study gave an insight on the effect of shear modification on molecular degradation of polyamide (Nylon) 6. It also studied the feasibility of utilizing mould filling simulation package to predict shear modification and degradation in injection molded product without the need for tedious molecular weight assessment. Injection molding procedure and mould filling simulations were implemented by varying mould configuration, injection pressure and melt temperature. Viscosity number test was performed to check the molecular weight changes of the samples with respect to the moulding parameters. Results showed that shear modifications caused some level of molecular degradation within the samples by lowering the molecular weight if compared with that of obtained from the original pellets. Shear modification was found to significantly affected by the mould configuration, melt temperature and injection pressure as displayed by the mould filling simulation results. The simulation results have also successfully shown useful correlation between shear modification mapping and molecular degradation measurement obtained via viscosity number test.

Automation of PTFE Handling System for Mould Filling Operation

Automation of PTFE Handling System for Mould Filling Operation

Effect of Pouring Conditions and Gating System Design on Air Entrainment During Mold Filling

Air entrainment during mold filling is a major source of oxide inclusion formation in metal casting. A model was recently developed by the authors to predict the volumetric air entrainment during pouring of metal castings. In the course of validating the model with experimental data for plunging liquid jets, it was shown that the air entrainment rate during mold filling depends fundamentally on the velocity and diameter of the jet formed by the pouring stream. In this study, the effect of more complex pouring conditions and gating system design on air entrainment is examined. Simulations are performed investigating the air entrainment characteristics of castings filled without a gating system, and with bottom-gated and side-gated filling systems. Results indicate that reducing the head height and pouring time, and the addition of a nozzle extension significantly reduces the air entrainment. In addition, using an offset pouring basin with a stopper and pressurizing the gating system further reduces the volume of entrained air. Simulation results also show that the generation of vortex flows inside the filling system is beneficial in reducing free surface turbulence, which results in less air entrainment and oxide inclusion formation during mold filling.

Simulation of Air Entrainment during Mold Filling: Comparison with Water Modeling Experiments

Oxide inclusions form during pouring of metal castings as a result of air entrainment. Recently, a model was developed by the authors to predict the volumetric air entrainment during pouring. It was found that the velocity, diameter, and turbulence intensity of the liquid stream affect the air entrainment rate during pouring. In this study, the developed air entrainment model is validated with water modeling experiments. In the water modeling studies, water was poured using a bottom pour ladle. The effects of nozzle opening, head height, nozzle diameter, and nozzle extension are simulated. The predictions compare favorably with the experimental measurements. Results indicate that low head height and short pouring time have a beneficial effect on reducing the air entrainment during pouring. In addition, a fully open nozzle and the use of a nozzle extension further reduce the amount of entrained air.

Simulating Mold Filling in Compression Resin Transfer Molding (CRTM) Using a Three-Dimensional Finite-Volume Formulation

Light-weight structural components are increasingly made of continuous fiber reinforced plastics (CoFRP), but their mass production is still very expensive. Because of its high automation potential, especially the Compression Resin Transfer Molding (CRTM) process gains more and more attention. Numerical mold filling simulations help to optimize this process and can avoid expensive experimental studies. Here, we present a new method to simulate mold filling in CRTM using a full three-dimensional finite-volume (FV) method. In comparison to known finite-element (FE) methods, it contains a compressible two-phase/Volume-of-Fluid description of the air- and resin-phase. This approach is combined with a moving mesh to account for the change of cavity height during the process, which results in a change of fiber volume fractions and thus permeabilities. We verify the method by comparison to analytic solutions of the Darcy equation and to solutions of state-of-the-art mold filling simulation software. The presented method enables CRTM mold filling simulation of complex parts, which is shown in two application examples. Furthermore, this shows the potential of using FV-based tools to simulate mold filling in RTM process variants containing non-constant cavity geometries.

The Particle Distribution in Liquid Metal with Ceramic Particles Mould Filling Process

Adding ceramic particles in the plate hammer is an effective method to increase the wear resistance of the hammer. The liquid phase method is based on the “with the flow of mixed liquid forging composite preparation of ZTA ceramic particle reinforced high chromium cast iron hammer. Preparation method for this system is using CFD simulation analysis the particles distribution of flow mixing and filling process. Taking the 30% volume fraction of ZTA ceramic composite of high chromium cast iron hammer as example, by changing the speed of liquid metal viscosity to control and make reasonable predictions of particles distribution before solidification.

Development of Advanced Cut-Cell Method for Higher Accuracy in Mold Filling Simulation

Development of Advanced Cut-Cell Method for Higher Accuracy in Mold Filling Simulation

Numerical Simulation of Shrinkage Formation Behavior with Consideration of Solidification Progress during Mold Filling Using Stabilized Particle Method

Numerical Simulation of Shrinkage Formation Behavior with Consideration of Solidification Progress during Mold Filling Using Stabilized Particle Method

Effect of Coat Permeability on Mold Filling in Expendable Pattern Casting Process of Thin Wall Aluminum Alloy Casting

Effect of Coat Permeability on Mold Filling in Expendable Pattern Casting Process of Thin Wall Aluminum Alloy Casting

A “Mold Filling” Model from Viscosity Measurements in a Strengthened Injection-Molded Reduced Glass Fiber Length Polyester Bulk Molding Compound

A “Mold Filling” Model from Viscosity Measurements in a Strengthened Injection-Molded Reduced Glass Fiber Length Polyester Bulk Molding Compound