Metal Casting

Download user presentations that focus on applications of FLOW-3D CAST for the metal casting industry from past users conferences.

2019

New frontiers in solidification modeling: FLOW-3D CAST v5.1

Michael Barkhudarov, Flow Science

The next release of FLOW-3D CAST, version 5.1 will see a major expansion of casting modeling capabilities. The new multi-component AlSi, AlCu alloy solidification model includes the effects of micro- and macro-segregation during the formation of primary, secondary and eutectic phases, predicts the microstructure and mechanical properties, such as elongation and ultimate tensile strength. Process workspaces have been extended to include centrifugal, continuous and investment castings, and sand core making. Exothermic feeder sleeves have been added to the Gravity Sand Casting processes. The High Pressure Die Casting Process is enhanced by the addition of direct importing of the shot profile as a function of distance along the shot sleeve.

The challenge to reduce powertrain components’ weight

Claudio Mus, Endurance Overseas, and Stefano Mascetti, XC Engineering S.r.l.

Lightweight materials are currently in high demand as low weight equals lower fuel consumption and consequently lower emissions for Internal Combustion Engines (ICE) and Hybrid Electric Vehicles (HEV), or longer range with a reduction of the battery cost for Battery Electric Vehicles (BEV). The fast-developing BEV segment could lead to an overcapacity in the aluminium casting industry around 2020 – 2025 if production technologies do not evolve to meet the need for lighter and cheaper components with a high level of quality. Driven by a challenging compromise between weight, cost and quality required by the latest generation automotive ICE components and sub-assembled systems (e.g., cylinder head covers), aluminium foundries are required to perform analysis in the early stages of the product development phase to assess the feasibility of lighter casting options. This paper will highlight how the HPDC process simulation can support the feasibility analysis and prevent high prototyping and tooling costs by analyzing the filling behavior of a cast part subjected to different thickness reductions.

An integrated approach to study the operating variables affecting the fluidity test of Al foundry alloys

Daniele Caliari and Giulio Timelli, University of Padova
Stefano Mascetti and Raul Pirovano, XC Engineering S.r.l.

The fluidity of an alloy is a key feature in Al foundry processes because it directly influences the mould filling stage. The relationship between fluidity and filling of the mould is clear, but even today, this understanding requires practical experience due to lack of experimental data. Furthermore, a universally standardized fluidity test has never been developed, and traditional testing methods show poor repeatability and an excessive scatter of the results due to “interferences” occurring during trials. This work studies the effect of certain process variables during testing of the fluidity of an A356 alloy by using an integrated approach based on numerical simulation and experimental trials. Operating variables such as melt superheat, pouring method, and holding time of liquid in the pouring basin have been analysed in detail by using Archimedean spiral testing. The results reveal how data scatter can be controlled by properly preheating the stopper and pouring ladle. Furthermore, the difference between the holding temperature in the furnace and the temperature of liquid in the pouring basin affects the holding time of the metal in the basin and thus the repeatability of the experiments.

A realistic model for exothermic feeders for gravity casting

Malte Leonhard, Flow Science Deutschland GmbH

A feeder (or riser) is a reservoir built into a metal casting mold to prevent cavities due to shrinkage. Most casting metals shrink when they solidify. This shrinkage potentially creates a void (or shrink hole) at the last point to solidify. Feeders prevent this by feeding molten metal to the casting as it solidifies, so that the cavity forms in the feeder and not in the casting. Exothermic feeders have walls (the feeder sleeve) which consist of a combustible material. When the hot melt enters the feeder sleeve this material is ignited and burns for a certain period of time, releasing heat which prevents the melt in the sleeve from freezing, ensuring that the feeder can continue to feed liquid metal into the casting. FLOW-3D allows the specification of a time-dependent heat source in a component. Alternatively, the ignition could be modeled using an event. What cannot be modeled with the standard version of FLOW-3D is the “burning through” of the component, i.e., the successive ignition and burning of different regions of the feeder sleeve. In contrast, the new model being presented allows a time-dependent heat release in each grid cell individually, thus realistically modeling the burning process. Furthermore, the new model accounts for the different thermal properties of the unburnt and burnt material.

Structural analysis of stress and deformation of a large foundry mould for gravity die casting process

Gabriele Taricco, CM Taricco

Stress and deformation analysis of the mould is very important in the gravity die casting process, especially in cases of large dimensions for big cast parts. High peaks in stress, generally reached during the filling and solidification phase, can put stress on the mould and create significant problems in terms of leakages of metal during the filling operation. They can also cause defects in the cast part, such as large burrs and other geometrical/dimensional problems. The aim of this work is to analyse how stresses are relieved by subdividing the tool into parts, compared to the simpler solution of a mould consisting of only two parts. To reach this goal, the latest version of FLOW-3D CAST has been used to simulate the thermal evolution of the mould during the whole cycle and to determine stress and deformation fields with the Fluid Structure Interaction model.

Casting die optimization by mean of IMPROVEit

Daniele Grassivaro, FORM S.r.l.

In our first experience with optimization software, we tested IMPROVEit coupled with FLOW-3D CAST. We found that coupling the two software works very well and has saved us considerable time compared to simulations run manually. This presentation will show results after we optimized feeding systems, overflows and ventings, and cooling channels of aluminum and magnesium dies for thin-walled castings with the application of vacuum and minimal spray.

Results and validation in simulation of ultrasonic treatment of aluminum A356

Eric Riedel, Otto-von-Guericke-University Magdeburg

Due to the constantly increasing requirements for metallic components in many technologically sophisticated branches of industry (e.g., automotive, aerospace or construction), there is a high demand for novel manufacturing solutions. In the case of aluminum casting alloys, the so-called ultrasonic treatment has been investigated for many years. So far, one of the obstacles for the widespread application of this technology is the challenging process simulation, due to the process-typical high frequencies (several kHz) and the small amplitude (e.g., 35 µm) which necessitate small calculation time steps and a very fine discretization. Using FLOW-3D, we were able to set up a basic model for the process simulation of ultrasonic treatment which covers the major effects (sound wave propagation, cavitation, acoustic streaming) and can be applied to casting processes. While the last contribution mainly focused on the feasibility study for the simulation of the ultrasonic treatment of aluminum, we have since been working on the evaluation of real castings in order to draw conclusions about the correctness of the simulation. It will be shown that the results obtained have a high agreement with the forecasts of the simulation. Additionally, a numerical approach for the derivation of the influence of cavitation on the resulting castings microstructure will be discussed.

Making Leonardo da Vinci’s “Colossal Horse”

Andrea Bernardoni, Università di Siena, Instituto e Museo di Storia della Scienza, Firenze Artes Mechanicae

Leonardo da Vinci’s legendary horse, designed to be an equestrian monument to Francesco Sforza, was one of the most audacious challenges of the Renaissance. No artist before Leonardo had attempted a casting of this size (over 7 meters high with an estimated weight of 70 tons of bronze) in a single pouring. The project was commissioned by Ludovico il Moro to honor his father, Francesco Sforza. Leonardo applied himself to the project between 1482 and 1499, during his first stay in Milan. He studied the anatomy of the horse and developed the practical details of the operation: an indirect method of casting (the first record of its reintroduction in the Renaissance period); the machines for handling and assembling the very heavy form; and a way to rapidly produce enormous quantities of bronze and to pour it into the mould. The story ended with the occupation of Milan by the French army in 1499. Ludovico il Moro was defeated, and Leonardo’s model of the horse was destroyed by French archers. Leonardo abandoned the project without being able to verify his casting process. Fortunately, he left notes and drawings describing the moulding process and the casting method, from which it was possible to reconstruct the 3D models of the foundry and attempt the numerical simulation of the casting. The results obtained were surprising and completely overturn the conclusions drawn previously, which considered the casting impossible to achieve. The presentation will be divided between historical narration, presentation of documents, and presentation of the results of the simulation which demonstrate the feasibility of a work never realized by Leonardo.

2018

Definition of a Robust Aluminum HPDC Process by Mean of Virtual Simulation, Design of Experiment and Taguchi Methodology

Claudio Mus, Endurance Overseas and Raul Pirovano, XC Engineering

In die casting processes, a high quality of the produced parts is required more and more. High quality products in high pressure die casting can be achieved by optimizing, often through numerical process simulations, the geometry of runners, gates, overflows and of the part itself, and by precisely calibrating the different process parameters like melt temperature, holding time, injection pressure and velocity, cooling rate and so on. Despite all of this, during the real production in a foundry there is always a certain variability of the process parameters which could lead to variations, sometimes significant, of the desired performances, and consequently to an increase of the scrap. For this reason, it is important to study the influence of the main process parameter on the product’s functional characteristics due to manufacturing variations and sources of noise which are variables that are impossible or expensive to control. The Taguchi methodology allows the effect of multiple variables to be analysed without performing an expensive full factorial design, which would require a large number of simulations or experiments, by choosing a limited and well-thought out selection of tests. In the present work, the Taguchi methodology has been applied to an HPDC process, and simulated with FLOW-3D CAST, analysing the influence of metal temperature and plunger speed to assess their effect on gas and shrinkage porosity. Consequently, the main guidelines for a more robust process have been identified.

Feasibility Study on the Simulation of Ultrasonic Treatment of Liquid and Solidifying Aluminium A356

Eric Riedel, Otto-von-Guericke-University Magdeburg

Ultrasonic treatment and its associated effects, namely cavitation and acoustic streaming, are promising for targeted treatment of liquid light metal alloys for achieving grain and structure refinement, and therefore, better mechanical properties. Furthermore, this treatment is considered a comparatively clean technology since no additions to the liquid are necessary. The simulation-based prediction of these process phenomena is an important requirement for better understanding, implementing and scaling of this technology for foundry processes. However, challenges remain including the high-frequency movement (20 kHz), small amplitude (35 mm) of the ultrasonic radiator and the resultant small time-step definition. Using FLOW-3D, we studied the ability to calculate the onset and expansion of cavitation and acoustic streaming for A356 (AlSi7Mg0,3) in the liquid state as well as during solidification. Our investigation shows that the results obtained with FLOW-3D are in good agreement with the theoretical and practical outcomes of other studies. The simulation of the solidification accompanying treatment indicates that the streaming caused by the ultrasonic treatment on the one hand supports the distribution of particles within the melt, and on the other hand counteracts a classical exogenous solidification process, thus promoting a more homogeneous casting structure.

Improvement of Shrinkage Macro-Porosity Prediction Capability

Daniele Grassivaro, Form Srl.

Many factors influence the formation of shrinkage macro-porosity, such as the geometry of the cast, position and geometry of gates, temperature of the mold, temperature and solid fraction of the metal after filling, intensification pressure, and alloy properties. In this study, we will focus on the influence of the position and geometry of gates. Simulations should help us to design a feeding system in order to minimize the shrinkage porosity, but we have seen that this is not true. Simulations usually show that gates get solidified suddenly after filling and then it seems they are not useful to compensate for the shrinkage, while in reality they continue to feed during the intensification phase. We will see how to tune our simulations to get results closer to reality. Thanks to: Denso Manufacturing Italy, site Barberino (FI).

Simulation-based Development of a Casting Process to Produce Clad Aluminum Strips

Stefan Heugenhauser1, Erhard Kaschnitz1, and Peter Schumacher1,2

1 Österreichisches Gießerei-Institut
2 University of Leoben

Casting liquid melt on a preheated substrate is a promising way to produce clad aluminum strips. A small-scale pilot plant to cast pure aluminum (Al99.8) on aluminum alloy plates (Al7075) was developed to investigate the formation of a metallurgical bond at the interface. A three-dimensional numerical simulation model of the casting device was set up using FLOW-3D to find suitable thermal conditions for the melt flow in the casting device as well as for the composite contact region. The model was iteratively calibrated using measured temperatures obtained from various casting experiments. However, the temperatures at the interface between the substrate and the clad alloy are not accessible by direct measurement. Therefore, a more accurate two-dimensional simulation of the middle section of the casting device was modeled. Furthermore, a sub-model of the two-dimensional simulation was derived to compute the thermal conditions at the interface as well as in its vicinity in extremely high temporal and spatial resolution. The simulation shows the occurring re-melting and solidification processes during the compound formation. The obtained results correlate very well with electrochemically etched cross sections of the cast bi-layer aluminum strips.

Support of the Design Process for Iron Castings

Malte Leonhard, Flow Science Deutschland GmbH

The design process of casting parts consists of several phases, each having different requirements in regard to the simulation of the process. The process starts with an approximate dimensioning of the gating and feeding system in order to estimate the amount of return scrap and by this provide a quick and simple assessment of the cost of the casting. Next is the design phase, in which different gating and feeding concepts are evaluated, and finally the design of the gating and feeding system is fixed. The result is a prototype with correct dimensions and minimal porosities. The final phase is the optimization of the tool design for mass production with the goal of minimizing material usage and scrap. This presentation illustrates how FLOW-3D CAST can aid the different phases of the design.

2017

Simulation of core making processes

Matthias Todte, Flow Science Deutschland GmbH
Olof Hilger, Simcast GmbH

With increasing demands on casting quality and a tendency to thinner-walled structures for high performance components, the production of the corresponding cores has become a very important factor, especially with regard to casting quality and productivity. The life cycle of a core, i.e., the production process and the behaviour in the casting process can be investigated using simulation to optimise the entire process and the core design. The core production process consists of two steps, the core shooting and the subsequent hardening of the binder. Using simulation, changes in core filling patterns and sand densities during core shooting can be analysed for different blow tube and vent configurations. By simulating the gassing of the core, the transport of curing gases like amine for cold box binders or the drying of inorganic binders can also be visualised for varying processing conditions. Finally, simulation allows the heat balance of the mould to be optimised. Using different examples, the presentation will show the typical usage of FLOW-3D to model the complete core making process.

Improvement of the heat transfer model: Radiation between solid components

Raul Pirovano and Palo Airoldi, XC Engineering

Thermal radiation is the radiation issued by a body due to its temperature, and it is one of the main ways through which solids can transfer heat, together with conduction and convection. Some realistic processes, such as investment casting, require that this phenomenon be included among the main physics in modelling and numerical simulations. In FLOW-3D v11.2, conduction, convection and a uniform radiation to void are modelled accurately, but radiation between solid components, keeping in account view factors and shadows, is missing. The aim of this work is therefore the development and the implementation of the solid-solid radiation model in a complete way, according to its main physical laws and peculiarities. Moreover, further developments have been made that will compute radiation between fixed components and also between simple moving objects.

2016

Keynote: Reducing Metal Damage during the Pouring Operation

Dave Goettsch, General Motors

Gating design plays an important role in the integrity of the final cast component. CFD tools are an indispensable design aid to deliver low velocity, balanced flow, with minimal air entrainment across the casting cavity. However, this accomplishment can be negated if significant damage occurs in the filling of the permanent mold pour basin and HPDC shot sleeve. There is little design freedom with existing cast equipment to eliminate the oxide leakers and sub-surface scrap due to this turbulent metal transfer. Several technologies will be discussed that can reduce or eliminate the plunging metal jet damage prevalent in permanent mold and HPDC metal casting operations.

Boundaries without Borders: Achieving Accurate Fill Times

Lucas Weyenberg, VERSEVO, Inc.

When using simulation software, it is important to know your boundary conditions and your initial conditions if it is a transient solution. If these conditions are not defined correctly, the solution will also be incorrect. For gravity casting simulations, there are several approaches that can be taken in order to define the correct boundary conditions: modeling the actual ladle pour, applying a pressure boundary based on fluid height of pour, or applying a velocity boundary that can be determined by the conservation equation for the intended gate velocity. During the pour, the person pouring the metal watches the metal height in the sprue and if it reaches the top they slow down or stop the pour until the metal drops below a certain height. The pour can be controlled using a time-dependent boundary condition or with the use of a new feature in FLOW-3D CAST called probe control that allows the user to define locations as a liquid level turning the flow on and off when the metal obtains the necessary height. In this presentation, we will look at different ways of applying the pressure boundary and velocity boundary in order to obtain the correct results with the least amount of simulation runtime.

Application of cavitation potential model to study a real case of die erosion

Daniele Grassivaro, Form S.r.l.

In high pressure die casting, where speed of the melt during die filling is very high, cavitation is one of the major causes of die erosion. Form S.r.l. as a die constructor is aware of this problem and decided to go deeper in the analysis of a real case where cavitation leads to premature die erosion. FLOW-3D CAST’s cavitation potential model was used to analyze this phenomenon. Then a solution was introduced by changing the geometry of the gate and tested in production.

Development and numerical simulation of a compound belt casting process

Stefan Heugenhauser1, Erhard Kaschnitz1, Tim Mittler2, Manuel Pintore2, and Peter Schumacher3
1Österreichisches Gießerei-Institut, 2Lehrstuhl für Umformtechnik und Gießereiwesen, 3Lehrstuhl für Gießereikunde

A new belt casting process has been developed to cast aluminium-aluminium alloy compound strips. It is based on a horizontal continuous casting process where the first strip is cast and transported on a glass fibre belt. At a defined distance from the location of the primary solidification, a second casting unit is placed where pure aluminium is poured on the upper side of the aluminium alloy strip. The local upper surface temperature of the substrate is essential for the forming of a sound metallurgical compound. Numerical simulation models of an existing single strip belt casting process were set up and extended to describe the new double strip casting process. The influence of several process parameters (cooling conditions and casting speed) and constructive modifications on the crucial surface temperature of the substrate were investigated. Temperatures measured in the single casting strip and in the copper cooling plates were used to calibrate the simulations. Casting parameters for the new strip casting process as well as the appropriate position of the second casting unit are derived from the simulation results.

Winner of the Best Presentation Award

Development and optimization of the casting technology of heavy vehicle suspension element

Marcin Malysza, Foundry Research Institute

Development of a new casting part is a very complex procedure requiring a combination of many elements of the design and manufacturing phases. The most efficient way is to use computer simulation to verify the design and production process. Over the years, the increasing capabilities of computer technologies has allowed for the development of an Integrated Computational Material Engineering (ICME). This method is a logical sequence that makes it possible to integrate the project activities, development of new manufacturing methods, selection of suitable material and final verification. Multithreaded operations significantly shorten the time required for the prototype production, which accelerates the implementation of the planned production of the designed casting. The presentation will describe the development process for a prototype suspension component for heavy machine, which will be used in a difficult wetland environment. The first stage of the work was to optimize the initial concept design of rocker arm of the vehicle using ANSYS. The analysis takes into account the optimization process based on the load schematic. Measurement data are used in the simulation to obtain maximum stress fields occurring in the conceptual construction of the rocker arm. The results were used to develop a design that provides a minimum stress in the construction. As a result of the optimization process, the final casting weight decreased by approximately 15%. Based on the results, a selection criteria for the casting alloy was proposed. Then the rocker arm design was modified in terms of the casting sand mold. The modification takes into account the necessary technological allowances, such as tilts and roundings. Finally the casting technology was designed and evaluated using FLOW-3D for the filling and solidification processes. The expected porosities for different gating and risering designs were evaluated to obtain the best possible casting technology.

Development and numerical simulation of a small-scale compound casting test plant

Stefan Heugenhauser1, Erhard Kaschnitz1, Falko Langbein2 and Peter Schumacher3
1Österreichisches Gießerei-Institut, 2Miba Gleitlager GmbH, 3Lehrstuhl für Gießereikunde

Strip-shaped aluminium clad materials are used in different industrial applications. Advantages are manifold resulting from the combination of different aluminium alloys readily forming a composite. These clad materials are usually produced by a mixture of hot and cold rolling. Manufacturing a clad strip by casting, forming a metallurgical compound, leads to a simplified production process and enables new combinations of aluminium alloys. The aim of this work is to produce clad plates of different aluminium alloys in a quasi-continuous casting process. A small-scale test plant for the casting of these compound plates with the dimensions of 230 mm x 200 mm x 20 mm was designed and built. The development of the test plant was based on 3D finite method simulations. FLOW-3Dwas used to find suitable thermal conditions for the composite casting region as well as for the melt flow in the casting device. The challenge was to find a model which is capable of numerically simulating the compound casting process with two aluminium alloys of different compositions. Therefore several simulation models have been evaluated whereas the most practical solution was a viscosity-based solidification model. The results were validated by experimental data. The test plant combined with the simulation model enables the study of the casting of selected material combinations with varying casting parameters such as casting speed, casting temperature and the thickness ratio of the compound layers.

Identification of optimal ladle design through oxides simulations

Mario Priasco, Teksid Aluminum

Through the present work Teksid Aluminum aims to identify the best ladle design and law of motion for minimizing oxide entrainment in the HPDC process before the metal is poured into the cylinder. In this study, four existing ladle designs were simulated and analysed with FLOW-3D. Some special considerations were made for the oxide output: to evaluate as best as possible the real oxide content in the ladle, the standard FLOW-3D oxide output has been compared with other useful FLOW-3Doutputs like the average turbulent energy or the metal temperature. Special care has been taken to speed up the calculation time, and create a robust and flexible setup. This way it will be possible to quickly simulate new designs, trusting in a universal setup, which is excellent for making good comparisons.

Investigation of mould leakages in a gravity die casting process

Gabriele Taricco, CM di Taricco

CM is an experienced gravity die casting mould maker society in Italy. Recently, CM encountered a gravity die casting mould that showed serious metal leakages in its bottom side, after very few cycles, due to geometric distortion of the mould in the process. The production of the cast part was compromised. Thanks to FLOW-3D and CM’s experience in this area, a quick analysis of the temperature field of the mould let the maker realize that the leakages were due to excessive mould stress and deformations caused by its mass distribution. An improved mould, with a modified mass distribution helped solve the problem. Additionally, with assistance from XC Engineering, a check with the new FEM module was done, as verification of the results reported here.

Simulation in support of the development of innovative processes in the casting industry

Matthias Todte1, Andreas Fent2 and Hubert Lang2
1
Flow Science Deutschland GmbH, 2BMW Group Leichtmetallgießerei Landshut

The application of simulation for the development of innovative casting processes at BMW Light Metal Foundry in Landshut, Germany is exemplified by the following processes:

  • Core blowing and core drying for inorganic sand cores
  • Pouring around and infiltration of inserts in high pressure die casting
  • Novel runner system for gravity casting (permanent mould)
  • High pressure die casting of complex structural parts

In addition, the presentation gives an overview of the application of salt cores in high pressure die casting.

Using FLOW-3D to model castings at MetalTek

Dick Emmerich, MetalTek International

MetalTek International (formerly Wisconsin Centrifugal) has been using FLOW-3D to model fluid dynamics and solidification of molten metal in centrifugal castings for over twenty five years. Turbulence, acceleration, pressure, thermodynamics, solidification and soundness are among the variables evaluated with the program. Understanding the process through modelling has assisted MetalTek in producing some of the highest quality and most complicated centrifugally cast geometries in the world. This presentation includes discussion on the physics of solidification, a brief comparison of sand and investment casting processes with FLOW-3D simulations, and descriptions, animations and FLOW-3D simulations of centrifugal casting processes. Videos taken inside the spinning die during water trials as well as during metal casting, will be compared to FLOW-3D simulations.

2014

Development of a contact pour ladle for casting automotive cylinder heads

Dr. David D. Goettsch, Jason R. Traub; General Motors Corp.

Automotive cylinder heads have stringent requirements for porosity and leak tightness that require clean metal delivered to the casting cavity. Great care is required to minimize damage to the molten aluminum at every stage in the process. Numerical analysis tools have greatly aided the design of gating systems to minimize in-mold damage. These same tools have been used to eliminate the metal damage associated with the filling of a pour basin. This study covers the development of a contact pour ladle for casting an automotive cylinder head.

Embedding of piezo ceramic modules in aluminum high pressure die castings

J. Köpf, A. Klassen, C. Körner, Institute for Material Science and Technology of Metals, Department of Materials Science, University of Erlangen – Nuremberg

The embedding of piezo ceramic modules in aluminum high pressure die castings is challenging but possible. The module not only has to stand enormous thermal and mechanical loads, but it also has to remain fixed in the mold with melt flowing around it at high velocities. Therefore, the fixation of the module plays a significant role in the embedding process. A fixation concept using expanded metal has been developed that stabilizes the module in the mold during the die casting process. While this supporting structure enables an embedding of the module without damage, it is also an obstacle to the fluid flow and thus affects the filling of the mold and the solidification of the melt. An optimal position and orientation of the module within the mold is studied by means of numerical simulations using FLOW-3D. Thereby, the focus is both on the quality of die filling as well as the infiltration of the expanded metal. The latter is of particular importance in cases of module positioning off the neutral axis where two different expanded metal geometries with differing mesh sizes are used.

Influence of die tempering channels design in die lifetime

Daniele Grassivaro, Form S.r.l.

A very important factor for the duration of a mold for high pressure die casting is its thermal behavior during production. Most mold manufacturers know this, but in fact accurate thermal analysis of the mold is rarely done due to time and budget, while leaving to experience/invention the design of thermoregulation circuits. In this study, we will present a fast and effective method to perform the thermal analysis of the mold and then draw conclusions in terms of life expectancy of the mold itself, considering a real case. Thanks to: Brabant-Alucast the Netherlands, site Heijen.

Lost foam casting simulation made easy

Harry E. Littleton, Alchemcast, LLC

Simulation of metal filling and solidification of the Lost Foam Casting Process has been difficult due to a lack of complete understanding of the process and an absence of accurate input data. The Lost Foam Casting Process is basically a ‘Full Mold’ process where the pattern must be replaced with metal. Complex events occur during this process which require intensive calculations. Fortunately Flow Science developed this Lost Foam Model in conjunction with the Lost Foam Consortium at UAB. Over the years, improvements in the software have made it more stable and accurate input data has been measured. This presentation will describe the important process parameters, the computational process and provide accurate input data. Several examples will be presented to illustrate the usefulness of FLOW-3D for Lost Foam simulations.

Numerical simulation of an aluminium strip casting process

Stefan Heugenhauser1,*, Erhard Kaschnitz 1, Peter Schumacher2
1Österreichisches Gießerei-Institut, 2Lehrstuhl für Gießereikunde

The general aim of this work is the development of an aluminum-aluminum compound strip casting plant. It is based on a horizontal continuous casting process where the strip is transported on a glass fibre belt. At a defined distance from the location of the primary solidification, a second casting unit is placed where pure aluminum is poured on the upper side of the aluminum alloy strip. The surface temperature of the substrate strip is essential for the forming of a metallurgical bonded strip. At first the temperature distribution of a single strip casting process was simulated with FLOW‑3D to study the process parameters and to provide specifications for the construction design of the future clad strip casting plant. The simulation was calibrated by various temperature measurements in a single strip casting machine used in production. Several process parameters (e.g., temperature and amount of cooling water, casting speed) and constructive modifications (e.g., the design of the water-cooled copper plates) were varied in 2D and 3D simulations to investigate its influence on the substrate strip temperature along the cooling section. The gained knowledge is used to define the position of the second casting unit. In addition, the melt flow was simulated in two different regions of the casting plant where the aluminum is still liquid to understand the real continuous casting process. One area of interest is the casting mould of the substrate strip and the other the tundish of the second casting unit.

A CFD approach for prediction of unintended porosities in metal matrix composite

Shizhao Li and Jon Spangenberg, Jesper Hattel; Department of Mechanical Engineering, Technical University of Denmark

Metal-matrix composites (MMCs) are materials with a great potential in applications related to lightweight structures, structural damping, and wear resistance. However, several experimental investigations in literature show that the fabrication process of MMCs is a delicate matter, which often results in incomplete infiltration. Numerical modeling can be a theoretical tool to reduce experimental work and provide useful information on the general behavior of the infiltration process. Previous numerical studies have focused on capturing the global propagation of the fully and non-fully saturated regions by the usage of the porous media/Darcy flow approach. Consequently, the unintended porosities have not been possible to determine with this method, since it does not include the infiltration pattern around the fibers or spherical particles. This work reports a numerical approach developed in FLOW-3D that enables for the simulation of the flow through the porous corridors of the preform. The geometrical representation of the preform which is input for the subsequent FLOW-3D analysis is conducted with an algorithm developed in MATLAB. The results of the FLOW-3D model illustrate that this method is capable of predicting unintended porosities in MMCs produced by an infiltration process.

3D flow and temperature analysis of filling a plutonium mold

Nicholas P. Orenstein, William D. Peach and Thomas A. Jachimowski, Manufacturing Engineering and Technologies Division, Los Alamos National Laboratory

The plutonium foundry at Los Alamos National Laboratory casts products for various special nuclear applications. However, plutonium’s radioactivity, material properties, and security constraints complicate the ability to perform experimental analysis of mold behavior. The Manufacturing Engineering and Technologies (MET-2) group previously developed a graphite mold to vacuum cast small plutonium disks to be used by the Department of Homeland Security as point sources for radiation sensor testing. Models using FLOW-3D computational fluid dynamics software are employed here to determine liquid Pu flow paths, optimal pour regimes, temperature changes, and pressure variations. A two-stage pouring basin consisting of a funnel and an angled cavity directs the liquid into a vertical runner. A stack of ten disk castings connect to the runner by horizontal gates. Volumetric flow rates were implemented to limit overflow into the funnel and minimize foundry returns. Simulations show that the flow follows a three dimensional path which includes cascading over the angled ledge and non-uniform cavity filling. The mold fills upwards with two to three disks receiving metal flow in a staggered sequence. Pressure builds up in the well, where impurities were found to settle in the actual mold. Simulation results showed negligible temperature change at casting temperatures of 850 °C molten plutonium and 500 °C graphite mold over a ten second timescale. In real castings, cooling requires approximately ten minutes, so temperature effects in such a superheated scenario are unlikely to affect solidification.

2013

Two examples taken from the CAE design of a racing motorcycle

Residual stress and aerodynamics analysis with FLOW-3D inside a design process

Roberto Saponelli, Protesa spa (Sacmi Group) – UNIMORE

This work presents an example of the various steps involved in a CAE process focused on increasing the performance of a racing motorcycle. The importance of having a very multidisciplinary chain, where each step is strictly connected (and influenced by) the previous or next one, is fundamental: each step cannot be considered by itself, and hence the choice of what has to be simulated in each step is not so trivial. The simulation speed, for example, must be not very long, and the designer has to pay particular attention in optimizing it simplifying at most the reality but keeping all dominant factors in its project. Among all the steps, two of them will be discussed in detail. First, an example of coupling between a topological optimization with Abaqus and the analysis of solidification and residual stress of the cast piece with FLOW-3D will be showed, highlighting the design of the cooling system. The solidification simulation, skipping the filling, can be a nice example of optimizing the design speed when major choices have to be made. A second case will demonstrate the results obtained by using FLOW-3D in calculating the external aerodynamics of the motorcycle, with actual limitations and potential improvements. Also in this case the speed of the calculation was reduced through a good use of the restart feature and nested blocks techniques.

Simulation parameters optimization and comparison with casting parts

Maxime Provost, SANDEN Manufacturing Europe

SANDEN is an automotive company which produces A/C compressors. The French factory is composed by 4 main units: the technical center, assembly, machining and finally the casting department. We produce aluminum casting parts with HPDC process on 7 die casting machines. Before the introduction of FLOW-3D in September 2012, we were using Magma in collaboration with our main die supplier. Now we use FLOW-3D mainly for new project introduction, to define the best ingate position, size and check filling/solidification conditions. During my studies, I had to complete a final project in the company. My mission was to best define parameters to have as realistic simulations as possible. In this context I did many simulations, with different parameters to define the most realistic one. During this presentation I will present my work on these parameters (mesh conditions, heat transfer coefficients, time step, plunger speed…) and our comparison with real parts.

Predicting castability of thin walled parts for the HPDC process using FLOW-3D

Rabi Bhola, Bholster Technologies

The question of how thin is too thin has been contemplated throughout the history of the HPDC process. To address this question, guidelines based on simplified mathematical models have been developed and revised over the years. More recently, however, there has been renewed interest in this topic from both the automotive and electronics industries. The automotive industry is interested in developing lighter structural castings, and the electronics industry is looking to manufacture housings out of metal, instead of plastics, at a low cost. Addressing these needs demands more than just guidelines. Current simulation tools account for the physics that dictate fluidity and therefore have the capability of predicting castability to a degree that far exceeds the guidelines. In addition, computers are now fast enough to model the process with sufficient resolution to make accurate predictions within a reasonable time. This work demonstrates how we can explicitly predict whether a thin walled part can be successfully cast. Variables accounted for are the thermal properties of the die steel, the surface finish of the die steel, thermal resistance of the applied die lube, and the thermal properties and initial conditions of the melt.

Analysis of the evolution of the molten metal flow during the injection phase in die-casting processes and its relation with air porosity

J.J. Hernández-Ortega, J. López, F. Faura, R. Zamora, and H.T. Sánchez; Dpto. de Ingeniería de Materiales y Fabricación, E.T.S. de Ingenieros Industriales, Universidad Politécnica de Cartagena

One of the most important problems encountered in die-casting processes is porosity due to air entrapment in the molten metal during the injection process. The aim of this work is to study numerically the evolution of the free surface of the molten metal during the injection phase in a die-casting machine with horizontal cold chamber for analysing the relation between the behavior of the molten metal and the air porosity in the final casting. To this end, numerical simulations of the fluid flow during the injection phase are carried out using FLOW-3D. Firstly, the evolution of the free surface is studied in the chamber for different plunger velocities for a given filling fraction. Then, the main characteristics of the flow during the initial filling of the die-cavity are analyzed for a wide range of operating conditions, paying particular attention to the transition between the flow injection chamber and the die cavity. For this study a die cavity with rectangular plate shape is used. The numerical results of the free surface are qualitatively analyzed using filling visualization experiments, which were carried out on a test bench using water as the working fluid in a transparent chamber and die model and a high-speed camera. Finally, to analyze air porosity and its relation with free surface evolution during the injection process, the numerical results are compared with radiographic images of aluminium parts manufactured with a die-casting machine.

Case studies, high pressure die casting

A. Pari, CRP Private Limited

This presentation will highlight some recent case studies where FLOW-3D was used not only to optimize the high pressure die casting process at CRP (India) Private Limited process, but also to prove them to its customers. The objective of the presentation is to rekindle, energize and encourage the fellow die-casting fraternity to use more and more simulation techniques. The manufacturing sector is undergoing a serious challenge amidst the global economic slowdown; it is high time that diecasters look inwards to find lasting solutions and simulations are the key.

Die casting design of DCT actuator body by CAE method

Han-Goo Kim1, Jung-Ho Lee1, Kwang-Hoon Park2 and Bok-Hyun Kang2
1R&D Center, KODACO2R&D Center, Soft-Tech International

In order to fabricate high quality casting products, exact casting design and control of manufacturing process accuracy is important. For the optimal casting design of an actuator body of double clutch transmission (DCT), various analyses were performed in this study by using the commercial code, FLOW-3D. The simulation has been focused on the molten metal behaviors and temperature during the mold filling stages for the sound casting products. Also internal defects were predicted by application of air fraction and feeding criteria.

High performance cooling system of die cast dies

Alex Reikher and Hal Gerber, Shiloh Industries

The main characteristics of the high pressure die cast process are the short fill time and rapid solidification rate. In order to facilitate the high heat fluxes, the cooling channels are cut into the cavity of the die cast die. Forced circulation of the fluid in the cooling system helps to reduce the temperature of the die, reduce the time of the liquid metal solidification, and prevent common, temperature related, die cast defects such as: surface cracks, heat sinks, solidification porosity, as well as die soldering. However, despite the presence of the active cooling system, the temperature of the die cast die steel can become quite high. It is primarily due to the convective resistance of the coolant, as well as the heat diffusion resistance of the die cast die steel. Negative effects of this overheating include steel problems – excessive wear, soldering and reduced die life, and processing problems – overspray, defect formations, pores, shrinkage, and surface imperfections. Preventing high temperature concentration during the die cast die process can be achieved by the design and implementation of the high performance cooling system. Nucleate boiling is one of the most attractive methods to achieve higher heat dissipation rate. This type of cooling takes advantage of the latent heat of vaporization of the fluid to provide fairly high heat transfer coefficients. In this presentation, a high performance cooling system was developed with the help of FLOW-3D. The cooling system was implemented and the results of the numerical analysis were verified using production die cast die.

Highly accurate gravity casting solidification

Stefano Mascetti, XC Engineering; and Niane Ngadia Taha, PSA Peugeot Citroen

The object of the present work is the research of optimal heat transfer parameters to put into FLOW-3D for a highly accurate tracking of temperature pattern, in a gravity casting process. Based on a standard gravity casting mold used for experimental testing, filled by 15 thermocouples, the history of numerical temperature probes in the same locations of the thermocouples have been compared against the recorded experimental histories. Parameters such as HTC, fsco, fscr, latent heat, solidification drag, roughness, and heat transfer to void have been optimized in order to match the two experimental vs. numerical curves. This work highlights the accuracy of the numerical results when coupled with good heat transfer parameters.

Improvements to the macro-shrinkage model for HPDC and application with squeeze pin

Daniele Grassivaro, Form Stampi

The comparison between some results from reality shows that the model for the evaluation of shrinkage macro-porosities used during solidification tends to over-predict the size of cavities. In particular, the model doesn’t consider the compressibility of the molten metal during the last stage of filling, when pressure rises up to 600atm, increasing considerably the liquid density and then affecting the shrinkage magnitude. The study was carried out on a part named “Venturi” for the automotive industry, designed to be produced with HPDC, alloy EN AN 46000. The part has a general low constant thickness except for a massive zone where it has to be drilled after casting to create water channels. The complete water-tightness of these channels is required, but it does not combine with the presence of shrinkage porosities. The process was simulated taking in consideration thermal die cycling and die cooling channels before filling, to achieve a temperature map as realistic as possible. Then the solidification was simulated several times, to fit the overall dimension of predicted cavities with those measured on the cast. Once the model was adjusted, a new solidification simulation was carried out considering the presence of a Squeeze pin, connected to the massive zone, to catch improvements in terms of shrinkage reduction. The study led to some changes to the alloy solidification parameters, and some ideas for further improvements to the model. Thanks to: Brabant-Alucast the Netherlands, site Heijen.

New curve optimization method and its application to shape design for die casting using a CFD simulation

Kenʼichi Kanazawa1, Kenʼichi Yano1, Junʼichi Ogura2 and Shuhei Baba3
1Department of Mechanical Engineering, Mie University, 2Yamaha Motor Co., Ltd., 3Flow Science Japan, Inc.

We propose a nonparametric curve optimization method based on a genetic algorithm. With conventional curve optimization methods, since the shape of a curve is defined by a finite number of design variables of real numbers and also has only finite flexibility, such methods may not provide the proper optimum curves. In contrast, the method we propose directly treats curves as solutions in the form of functions, without design variables, and can effectively optimize the curves by numerically synthesizing several functions. We demonstrate the effectiveness of the curve optimization method by applying it to an optimum design problem for die casting using a computational fluid dynamics (CFD) simulation.

Speed-up product development by combining 3D modeling 3D simulation and sand mold printing

Jyrki Hänninen, Hänninen Engineering Oy

Computer simulation is widely used in the manufacturing industry, especially in areas where the processes can be modelled using computers. What is more, there is no system yet available that automatically suggests the best system for the user. Manufacturing processes are often one of the most complex phenomena especially in the foundry industry due to the high number of physical processes involved simultaneously and their strict net of relations. Often simulations are used when the casting system is not defect free and therefore, it does not give directly the total cost savings. However, when casting processes require absolutely defect free castings in the first trial, it means that simulation must be used and then the cost savings can be calculated including lead time and rapid prototyping. Hanninen Engineering has developed a totally new business concept in which prototypes are made by combining castings processes with advanced simulations using FLOW-3DCast in order to achieve complex molds and cores with sand 3D printing methods. Hanninen Engineering is developing very demanding RPT castings for automotive, machine building and marine industries including clients such as Wärtsilä, ABB Motors and Generators, Agco SisuPower and Bombardier.

Simulating sleeve designs for the best performance and life

Mark Littler1 and Melissa Carter2
1Littler Diecast Corporation, 2Flow Science

Shot sleeves used in cold chamber die casting are a critical but consumable part of the process. The goal of this project is to use FLOW-3D to simulate the effects of heat on the performance of a shot sleeve. Good performance of a sleeve is indicated by dimensional stability throughout the entire casting lot, as well as by long life. Molten aluminum will affect the sleeve shape by both the thermal and chemical processes, and managing the heat in a sleeve is proven to extend sleeve and tip life. Simulations will be run on a baseline case of a sleeve with no cooling lines as well as a case with internal cooling lines circulating hot oil through the sleeve. The FSI model will allow us to examine the dimensional effects of heat imbalance in the steel, and the heat transfer model will allow us to see how the heat moves through the body of the sleeve in each case.

The application of FLOW-3D in die casting mold design with central gate

Yu-Che Lin, JONSHIN Mold Industrial Studio

We will do a presentation of a die casting mold design with a central gate in the user conference. First, we will introduce the mold design. Then we will present the film of the casting process and the animation of the mold mechanism. Finally, we will present the advantages and disadvantages of the central gate design and the simulation results of FLOW-3D.

2012

Analyses of solidification parameters during the die cast process

A. Reikher and H. Gerber; Albany Chicago LLC

Advantages of the die cast aluminum alloys such as light weight, high corrosion resistance and relative high strength, secured its place as a material of choice in the automotive industry. Wide spread use of the aluminum die cast parts applications as well as an increase in complexity of the part design require more close control over solidification characteristics. Thermal analysis has become an integral part of the die cast process development. Structural applications of the die cast parts require thermal analysis not only predict process parameters but also give an understanding of the mechanical properties as well. There are close relations between physical and micro-structural parameters of the die cast parts. The most widely used, SDAS (secondary dendrite arm spacing), can be correlated to physical parameters such as UTS (ultimate tensile strength) and percentage of elongation. The high-pressure die-cast process is a precision manufacturing process in which molten metal is injected at high pressure and velocity into a permanent metal mold. As the metal enters the die cavity through the gate system, it displaces gas that occupies the cavity in the beginning of the process. In order to allow for adequate gas evacuation, ventilation channels are cut in the molds that connect the die cavity with the outside atmosphere. After the mold cavity is completely filled, the metal continues to flow into the ventilation channels until it completely solidifies. The high fluidity of the die-cast alloys allows them to easily flow in very thin channels. As a result, it is important to incorporate metal flow and solidification in thin channels in the overall die-cast process development. Understanding flow and solidification in narrow channels often becomes critical in developing parameters for the die cast process. However, owing to a small aspect ratio of the channel height to its length, numerical analyses require a large number of computational cells in order to achieve a converged solution. For that reason, numerical analysis, as a general rule, is conducted in the main cavity only. In the presented paper we used measured solidification curve of the commercial aluminum alloy A380 in combination with interactive Fourie procedure to determine solidification characteristics of the alloy. Calculated solidification parameters were subsequently imported in commercial software FLOW-3D. Flow and solidification were analyzed in several ventilation channels. Results of the numerical simulations were verified against an actual casting produced by the high pressure die cast process. Then FLOW-3D was utilized to conduct a parametric study to determine metal flow length with various liquid metal velocities, temperature and height of the ventilation channel. As a result some design parameters were established to assist in ventilation channels design.

Optimal algorithm to multimodal solution space formed by FLOW-3D

Yoshifumi Kuriyama1 and Ken’ichi Yano2
1
Gifu National College of Technology, 2Mie University

The aim of this study is to design a solution search algorithm that requires a smaller population to find a solution that can be applied to the production of high-quality products. Results showed that in comparison with Genetic Algorithms, the proposed method could better optimize the plunger velocity in die-casting resulting in less air entrainment. The experimental results demonstrated that optimization with the proposed method corresponded accurately to superior production by die-casting.

Optimisation of HPDC and GDC process and design using flow simulation — case studies

K. Raghavachary, Aurangabad Electricals ltd.

This presentation will highlight some case studies where flow simulation results helped in the optimisation of the HPDC and GDC process, including 1) product design improvements; 2) achieving the quality as per customer requirement; 3) optimisation of gate, overflow and venting channels in die and their location; 4) optimisation of cooling channels in the die and 5) optimisation of feed system for gravity casting. These results give Aurangabad Electricals ltd many solutions and its customers a lot of confidence.

Optimization of gating design in unified high pressure die-casting products

Han-Goo Kim1, Jung-Ho Le, Bok-Hyun Kang2, Kwang-Hoon Park
1R&D Center, KODACO, 2R&D Center, Soft-Tech International

In the past, cost reduction and performance enhancement were among the most important factors in automobile development research. In recent years, however, the focus has been on the factors such as the pollution reduction and the fuel efficiency, as the environmental issues have drawn much attention. In order to produce lightweight components of automobiles to improve the fuel efficiency, a design of thin-walled products, design optimization and unified components technology is important. Meanwhile, to make these unified components by high pressure die casting has a problem of increasing shrinkage and porosity defects as the wall thickness of connecting parts increases. In the present study, the effect of design factors of gating systems and the process variables on the casting defects during high pressure die casting was investigated through numerical simulation by using a commercial software, FLOW-3D. From the simulation results of the original design, it is shown that the in-gate region of the runner solidified much faster. The modified gate design with an increased wall thickness of the in-gate region and with a slight shifting in the direction of the thick-wall showed slower solidification than the original gate design, which can be achieved by an increased pressurization time on products than the original design. It is, therefore, believed that the optimization of the gating system can reduce shrinkage and porosity defects during a lightweight component manufacturing process.

Predictions of process variables in producing a bulk amorphous alloy by planar flow casting

Bok-Hyun Kang, Kwang-Hoon Park, Ki-Won Hong, Sung-Yul Yoo; R&D Center, Soft-Tech International

Since bulk amorphous alloys have excellent mechanical, magnetic, and corrosion resistant properties, these can be produced much thinner than traditional materials for structural application purposes. However, it is very difficult to produce these in their strip forms by the common casting processes due to their high viscosities. Planar Flow Casting (hereafter, PFC) is one of the methods to manufacture the bulk amorphous strips, whose qualities are subject to many process variables such as a slit-shaped nozzle, applied pressures, roll speeds, fluid viscosities, the distance between the moving chill roll and the nozzle lips, etc. In this study, fluid flow and heat transfer in the molten pool (puddle) of the bulk amorphous strips during PFC was analyzed by using the commercial flow software, FLOW-3D. From the analysis it is shown that the change in downstream velocity of the molten metal with ejection pressure is influenced by the dynamic viscosity of the material, and that a velocity difference between the center and the edge of the nozzle exists. The rotating roll speed as well as the gap between the rotating roll and the nozzle affects greatly the puddle formation, making it necessary to increase the roll speed when the gap is decreased.

The application of FLOW-3D in metal castings

Yu Che Lin; JONSHIN Mold Industrial Studio

This study represents two practical cases to show the applications of FLOW-3D on the gravity and die casting procedures of aluminum alloy. Consider a metal mold for aluminum alloy gravity casting in Case 1. According to the FLOW-3D analysis, we redesign the gating and runner system to improve the flow motion and gas exhaust and make the highest quality products possible. Consider a metal mold for aluminum alloy die casting in Case 2. FLOW-3D simulated results show satisfactory agreement with the actual die casting flow patterns.

Simulation of melting of alloying materials in steel ladle

Petri Väyrynen, Lauri Holappa, and Seppo Louhenkilpi; Aalto University

Additions to the liquid steel in ladle are performed to attain the desired steel composition and to purify the steel to improve its cleanliness. The added materials differ regarding to size, shape, density, melting point, latent heat of fusion, etc. Further, the liquid steel composition, temperature and flow conditions influence the phenomena in heating, melting and dissolution of the added object. Solidification of steel shell around the added object is an initial event in lump additions too. In this study different phenomena were modeled for different materials by using FLOW-3D. Simulation of the shell formation procedure was divided into two stages. In the first stage a cold alloy lump is introduced into the liquid steel and solid shell starts to form, it grows to a maximum thickness and then starts to melt and finally disappears. In the second stage the lump itself melts, if not yet molten, and is mixed into the bulk steel in the ladle. Simulations were done for aluminum, FeSi, FeMn, SiMn and FeCr with selected lump sizes. Solid shell development and existence as well as melting were presented as a function of time. Results were validated by comparison with experimental observations in the literature covering relevant range of alloying materials and flow velocities. According to validations, simulations of real alloying materials using developed model can be done with good accuracy for industrial heats in argon stirred ladles.