Simulation Of Casting Process Research Articles

Effect of mold designs on molten metal behaviour in high-pressure die casting

This paper presents a research study conducted in a local automotive component manufacturer that produces aluminium alloy steering housing local and global markets. This study is to investigate the effect of design modification of mold in die casting as to improve the production rate. Design modification is carried out on the casting shot of the mold. Computer flow simulation was carried out to study the flow of molten metal in the mold with respect to the mold design modification. The design parameters of injection speed, die temperature and clamping force has been included in the study. The result of the simulation showed that modifications of casting shot give significant impact towards the molten flow behaviour in casting process. The capabilities and limitations of die casting process simulation to conduct defect analysis had been optimized. This research will enhance the efficiency of the mass production of the industry of die casting with the understanding of defect analysis, which lies on the modification of the mold design, a way early in its stages of production.

Gating system design for the space device case using T-Flex CAD

The judicious selection of gating system for the consumable pattern takes a lot of time, labour and other significant resources. The modern design technologies provide quick and effective ways for gating system calculation and casting process simulation. Gating system modeling allows estimating different kinds of defects which can occur at the developing stage of casting process. Moreover, it is possible to modify the whole gating system configuration if some parameters are changed. Analyzing these data and modifying the gating system characteristics high quality of castings can be achieved.

FRPの確率的RTM成形プロセスシミュレーションにおける裾野分布の解析

There is a growing need for molding process simulation of fiber reinforced plastics (FRP) in determining an appropriate set of process parameters, because a large number of process parameters exist and moreover those parameters have uncertainty or variability. Stochastic process simulations have been studied so far such as the Monte Carlo simulation (MCS), which provides us the expected value and standard deviation of the quantity of interest (QoI), considering the variability of input parameters. However, the results in the tail distribution were not highlighted except the authors' previous reports. This paper proposes a modified sampling scheme named stepwise limited sampling (SLS) to generate sampling points more efficiently and accurately in the multi-dimensional input parameter space, which lead to the tail distribution of QoI. The proposed method was applied to a resin transfer molding (RTM) process simulation considering 31 random parameters. Compared to the conventional MCS using 10,000 sampling points, it was demonstrated that enough number of cases in the tail distribution was analyzed by the modified method using only 1,700 sampling points.

DETERMINATION OF HEAT TRANSFER COEFFICIENT BETWEEN ALUMINUM CASTING AND GRAPHITE MOLD

Graphite molds can be used to produce titanium, nickel, copper, aluminum and zinc castings. Using of the graphite molds provides a high cooling rate. Moreover no die coatings and lubricants are required. To get appropriate results of the casting process simulation in graphite molds it is necessary to know thermophysical properties of materials and boundary conditions such as interface heat transfer coefficients, but they are still unknown. The most important properties are heat transfer coefficient between casting and mold, and between mold parts and between mold and environment. The heat transfer coefficient h (iHTC – interface Heat Transfer Coefficient) was determined between cylindrical aluminium (99,99 % Al) casting and mold made of low-ash graphite. The mold was produced by milling graphite blocks on the CNC machine. The heat transfer coefficient was determined by minimizing the error function, representing the difference between the experimental and obtained by simulation temperature in the mold during pouring, solidification and cooling of the casting. The dependences of the iHTC between aluminium and graphite on the temperature of the casting surface and time elapsed from the start of pouring of the casting. Determined values of the heat transfer coefficient at metal temperatures 1000, 660, 619 and 190 °С are 1100, 4700, 700 and 100 W/(m2 ·К) respectively. Therefore, with decreasing of the melt temperature from 1000 °C (pouring temperature) to 660 °C (aluminium melting point), the heat transfer coefficient increases. After casting surface forming and lowering its temperature, the heat transfer coefficient decreases. Decrease of the iHTC at temperatures below 660 °C (lower the melting point) is associated primarily with the appearance of an air gap between the mold surface and casting surface as a result of linear shrinkage. The iHTC between the mold parts (graphite– graphite) is constant 1000 W/(m2 ·К). The heat transfer coefficient between graphite and the air environment is 12 W/(m2 ·К) at the mold surface temperature up to 600 °C.

Modelling and simulation of local mechanical properties of high silicon solution-strengthened ferritic compacted graphite iron

This study focuses on the modelling and simulation of local mechanical properties of compacted graphite iron cast at different section thicknesses and three different levels of silicon, ranging from about 3.6% up to 4.6%. The relationship between tensile properties and microstructure is investigated using microstructural analysis and statistical evaluation. Models are generated using response surface methodology, which reveal that silicon level and nodularity mainly affect tensile strength and 0.2% offset yield strength, while Young′s modulus is primarily affected by nodularity. Increase in Si content improves both the yield and tensile strength, while reduces elongation to failure. Furthermore, mechanical properties enhance substantially in thinner section due to the high nodularity. The obtained models have been implemented into a casting process simulation, which enables prediction of local mechanical properties of castings with complex geometries. Very good agreement is observed between the measured and predicted microstructures and mechanical properties, particularly for thinner sections.

A Statistics-Based Cracking Criterion of Resin-Bonded Silica Sand for Casting Process Simulation

Cracking of sand molds/cores can result in many casting defects such as veining. A robust cracking criterion is needed in casting process simulation for predicting/controlling such defects. A cracking probability map, relating to fracture stress and effective volume, was proposed for resin-bonded silica sand based on Weibull statistics. Three-point bending test results of sand samples were used to generate the cracking map and set up a safety line for cracking criterion. Tensile test results confirmed the accuracy of the safety line for cracking prediction. A laboratory casting experiment was designed and carried out to predict cracking of a cup mold during aluminum casting. The stress–strain behavior and the effective volume of the cup molds were calculated using a finite element analysis code ProCAST®. Furthermore, an energy dispersive spectroscopy fractographic examination of the sand samples confirmed the binder cracking in resin-bonded silica sand.

Optimized Durability Prediction of Cast Iron Based on Local Microstructure

The microstructure of cast iron is decisively influenced by the composition, the applied metallurgy and the process conditions. Differences in microstructure mainly influence the local mechanical properties. In conventional durability predictions, local microstructure and local defects in the casting are not taken into account. The assumption of homogeneous material properties applying one single material dataset for the prediction of fatigue strength usually leads to a misinterpretation in the assessment of local risks. Furthermore, the material potential of the casting will not be used in full. Safety margins result in an over design and unnecessarily high weight of the component as well as increased casting part costs. The designer can only benefit from the potential of the material cast iron, if the real spectrum of local material properties is considered in durability calculations. Current casting process simulation tools allow the prediction of local microstructure and resulting static mechanical properties as a function of alloy composition, applied metallurgy and local solidification and cooling conditions. Within a German research project, the link between casting process simulation and cyclic material properties was established for different cast iron materials for the first time. S–N curves (Woehler curves), which depend on local microstructure close the gap between casting process simulation and lifetime analysis. This innovative approach leads to improvements in lifetime predictions. It was shown that the consideration of local fatigue strength based on this innovative approach leads as well to an increasing number of cycles to failure as to a correct prediction of the location of crack initiation. Compared to the conventional design of castings, a substantial qualitative and quantitative improvement in assessing the real performance of cast iron materials can be realized.

Reduction of Oxide Inclusions in Aluminum Cylinder Heads Through Autonomous Designs of Experiments

Oxide inclusions, which are created during the pouring process of aluminum alloys, are the main cause of leaks in castings. This contribution shows how the integration of autonomous design of experiments (DOEs) into the casting process simulation tool MAGMASOFT® provides the basis for the evaluation and subsequent optimization of process parameters in the melt transport and pouring process, which are responsible for the creation and distribution of oxide inclusions. At the same time, quality criteria describing the creation of oxides during the casting process of cylinder heads were evaluated quantitatively. The utilization of autonomous DOEs creates variations of the gating system and process parameters autonomously. It will be shown that autonomous DOEs are leading to optimized gating designs and process parameters resulting in a significant reduction of oxides in castings. The experiments supported by simulation were accompanied and validated by high-speed video technology and the PREFIL-measurement technology.

Simulation tools in enhancing metal casting productivity and quality: A review

Casting simulation softwares are increasingly being used in modern foundries and metal casting industries. Softwares simulate the casting process in a virtual domain and provide insight into mold filling, solidification and cooling, and casting defects. Casting simulations allow designers to model, verify, and validate the process followed by optimization of design and process parameters before they actually put into practice. This article aims at exploring the methods of modeling and simulation of metal casting processes with reference to some related case studies. Most commonly available casting simulation softwares and the underlying mathematical models used are briefly introduced. Casting process simulation together with the results obtained is well explained. Case studies from the literature revealed that simulation tools are playing a vital role in producing high-quality defect-free cast products by providing an in-depth understanding of mold filling and solidification, gating, runner and feeding system design, and other process parameters. Recent efforts on integrating the casting simulations to mechanical performance simulations are discussed which is quite promising in predicting the service life of cast products. It is concluded that simulations have been well established in metal casting processes and more developments in simulation tools are needed for reliability prediction of castings.

Contactless inductive flow tomography: basic principles and first applications in the experimental modelling of continuous casting

Contactless inductive flow tomography (CIFT) aims at reconstructing the flow structure of a liquid metal from the magnetic fields measured at various positions outside the fluid body which are induced by the flow under the influence of one or multiple applied magnetic fields. We recap the basic mathematical principles of CIFT and the results of an experiment in which the propeller-driven three-dimensional flow in a cylindrical had been reconstructed. We also summarize the recent activities to utilize CIFT in various problems connected with the experimental simulation of the continuous casting process. These include flow reconstructions in single-phase and two-phase flow problems in the Mini-LIMMCAST model of slab-casting, studies of the specific effects of an electromagnetic stirrer attached to the Submerged Entry Nozzle (SEN), as well as first successful applications of CIFT on the background of a strong electromagnetic brake field. We conclude by discussing some remaining obstacles for the deployment of CIFT in a real caster.

Application of RSM to Optimize Moulding Conditions for Minimizing Shrinkage in Thermoplastic Processing

This study focuses on the analysis of plastic injection moulding process simulation using Autodesk Moldflow Insight (AMI) software in order to minimize shrinkage by optimizing the process parameters. Two types of gates which is single and dual gates have been analysed. Nessei NEX 1000 injection moulding machine and P20 mould material details are incorporated in this study on top of Acrylonitrile Butadiene Styrene (ABS) as a moulded thermoplastic material. Coolant inlet temperature, melt temperature, packing pressure and cooling time are selected as a variable parameter. Design Expert software is obtained as a medium for analysis and optimisation to minimize the shrinkage. The polynomial models are obtained using Design of Experiment (DOE) integrated with RSM Center Composite Design (CCD) method in this study. The results show that packing pressure is a main factor that contributed to shrinkage followed by coolant inlet temperature, while melt temperature and cooling time has less significant for both single and dual gates. Meanwhile, single gate shows a better result of shrinkage compared to the dual gates.

Numerical simulation and process optimization of squeeze casting process of an automobile control arm

Taking the automobile control arm as the research object, using MAGMASOFT, to simulate the squeeze casting process, the position of the shrinkage cavity and shrinkage defects in the casting process is accurately predicted. The results show that there exist shrinkage defects in the end and middle of the upper arm. The top of the upper arm is partially squeezed, and partial squeeze pressure is 130 MPa, the hotspot is eliminated. In the middle of the upper arm, the cooling line is added, so the control arm is whole to meet the order of solidification principle, and shrinkage defects are eliminated.

Al-Si and Al-Si-Mg Cast Alloys Shrinkage Porosity Estimation

Abstract US A356 and US 413 cast aluminium alloys shrinkage characteristic have been discussed in the present study. Specific volume reduction leads to shrinkage in castings and it can be envisaged as a casting defect. Finite difference based casting process simulation software has been used to study the shrinkage characteristic and it is quantified using mathematical formulae. The three dimensional model of the shrinkage defect has been constructed using CAD application software. Shrinkage characteristic has also been quantified through experimental validation studies and compared well with casting process simulation. Shrinkage characteristic study and control is essential for producing defect free castings. Influence of casting shape on the shrinkage characteristic has been studied in this paper.

Numerical simulation of casting process to assist in defects reduction in complex steel tidal power component

In order to reduce defects and improve casting quality, ProCAST software is performed to study the solidification process of discharge bowl. Simulated results of original casting process show that the hot tearing is serious at the intersection of blades and outer or inner rings. The shrinkage porosity appears at the bottom of discharge bowl and the transition area of wall thickness. Based on the formation mechanisms of the defects, the structure of chills attached on the outer surface of discharge bowl casting is optimized. The thickness of chills ranges from 25mm to 35mm. The positions of chills corresponded to the outer surface of the T-shaped parts. Compared to the original casting design (without chills), the hot tearing and shrinkage porosity of the discharge bowl are greatly improved with addition of chills.

Experimental Study and Numerical Simulation of Injection Molding Process for Special-shaped Plastic Part

Taking the special-shaped plastic part as the research object, experimental study and numerical simulation of injection molding process were performed using numerical simulation technology, orthogonal experiment method, software Moldflow, injection machine and coordinate measuring machine (CMM). The better feeding system and optimal molding process parameters were proposed and qualified products were produced. The research results show that the efficiency of the simulation guidance would be significantly improved by combining the CAE technology and production experience.

RESEARCH ON THE INTERFACIAL HEAT TRANSFER COEFFECIENT BETWEEN CASTING AND CERAMIC SHELL IN INVESTMENT CASTING PROCESS OF Ti6Al4V ALLOY

Investment casting process is an important way to get complex parts of titanium alloy. However there are few research on the interfacial heat transfer coefficient (h) between casting and shell thus the temperature simulation of investment casting process of titanium alloy is often inaccurate. In order to get a relatively accurate h, *中欧航空科技合作项目,欧盟第七框架项目,国家重点基础研究发展计划项目 2011CB706801,国家自然科学基金项目 51171089和 51374137,国家重大科技计划项目2012ZX04012011,以及国家高技术研究发展计划项目2007AA04Z141资助 收到初稿日期: 2015-01-12,收到修改稿日期: 2015-05-02 作者简介:邵 珩, 1989年生,男,博士生 DOI: 10.11900/0412.1961.2015.00037 第976-984页 pp.976-984

Modelling and simulations of ductile iron solidification- induced variations in mechanical behaviour on component and microstructural level

The mechanical behaviour and performance of a ductile iron component is highly dependent on the local variations in solidification conditions during the casting process. Here we show a framework which combine a previously developed closed chain of simulations for cast components with a micro-scale Finite Element Method (FEM) simulation of the behaviour and performance of the microstructure. A casting process simulation, including modelling of solidification and mechanical material characterization, provides the basis for a macro-scale FEM analysis of the component. A critical region is identified to which the micro-scale FEM simulation of a representative microstructure, generated using X-ray tomography, is applied. The mechanical behaviour of the different microstructural phases are determined using a surrogate model based optimisation routine and experimental data. It is discussed that the approach enables a link between solidification- and microstructure-models and simulations of as well component as microstructural behaviour, and can contribute with new understanding regarding the behaviour and performance of different microstructural phases and morphologies in industrial ductile iron components in service.

A fast and efficient adaptive parallel ray tracing based model for thermally coupled surface radiation in casting and heat treatment processes

A new algorithm for heat exchange between thermally coupled diffusely radiating interfaces is presented, which can be applied for closed and half open transparent radiating cavities. Interfaces between opaque and transparent materials are automatically detected and subdivided into elementary radiation surfaces named tiles. Contrary to the classical view factor method, the fixed unit sphere area subdivision oriented along the normal tile direction is projected onto the surrounding radiation mesh and not vice versa. Then, the total incident radiating flux of the receiver is approximated as a direct sum of radiation intensities of representative “senders” with the same weight factor. A hierarchical scheme for the space angle subdivision is selected in order to minimize the total memory and the computational demands during thermal calculations. Direct visibility is tested by means of a voxel-based ray tracing method accelerated by means of the anisotropic Chebyshev distance method, which reuses the computational grid as a Chebyshev one. The ray tracing algorithm is fully parallelized using MPI and takes advantage of the balanced distribution of all available tiles among all CPU's. This approach allows tracing of each particular ray without any communication. The algorithm has been implemented in a commercial casting process simulation software. The accuracy and computational performance of the new radiation model for heat treatment, investment and ingot casting applications is illustrated using industrial examples.

Integrated Computational Materials Engineering and Modelling of Shape Casting Processes - Needs, Benefits, Limitations and Hurdles

In this paper, the industrial needs and potential benefits of ICME for shape castings are described from the point of view of a commercial provider of casting process simulation tools. At the same time, the paper addresses the challenges, limitations, and hurdles regarding the extent to which ICME is or can be adopted on an industrial scale for shape cast components. The discussion is backed by concrete examples illustrating the advantages and limitations of integrating models and simulation in the design chain of cast components, in the design and analysis of the processing route of a casting, as well as over the different length scales through which the structures and corresponding behaviorof the cast material are determined. The biggest impact of the ICME approach will only be apparent when the increased accuracy or level of detail provided by the methodology is truly necessary, because it leads to changes in design decisions for the product or manufacturing process.

High Speed Reactive Resin Transfer Moulding (RTM) Process Simulation for Mass Production of Automotive Structural Parts

High Speed Reactive Resin Transfer Moulding (RTM) Process Simulation for Mass Production of Automotive Structural Parts