Dr.S.Shamasundar, Mrs. Damayanthi Ramachandran, Mr.N.S.Shrinivasan, Manjunatha T. M
Investment casting process used for precision component manufacture calls for accurate methoding design. The development times can be very high in the conventional trial and error based process design. In the current competitive environment, there is a need for the foundry and casting units to develop the components and the process at quick response times. Further, the costs of development also have to be kept low to be competitive. In these circumstances, FINITE ELEMENT ANALYSIS based computer simulations can be of immense value to the casting units. Authors have used ProCAST a commercially available FEM package for foundry and casting simulation for analysis of investment casting of a variety of components. (ProCAST can be used as a simulation tool for analysis of other casting processes such as sand casting, high pressure / gravity / low pressure die casting as well. However these are not part of the focus of this particular paper). By computer simulation of the casting process, the flow of the molten metal in the cavity, the heat transformation, the solidification, grain formation, shrinkage and stress evolution can be visualized. The details are seen on the computer in graphical form, which helps the designers to visualize the defects in the process design, to analyze the causes for the defects (such as hot tears, shrinkage porosities, cold shuts etc.). Further, the modified gating designs can be tried without resorting to the actual production of tooling. In investment casting process, the shell making, shell drying, shell heating and casting processes can be simulated in ProCAST. The paper describes general principles of applying finite element analysis computer simulation to investment casting processes. Prediction of defects such as shrinkage porosity is demonstrated. Using of computer simulation as a virtual investment-casting environment is demonstrated.
Gravity die casting process 鈥 die design process optimization
Dr.S.Shamasundar, V.Gopalakrishna, Manjunatha, Badrinath
The design of dies, gating and risering system in gravity die casting or permanent mould casting by conventional approach is a difficult process and time consuming. Gravity die casting used for non-ferrous casting applications is increasingly used in the foundries today as an economically viable casting process. The conventional trial and error based die design and process development is expensive and time consuming. Such a procedure also 鈥淭imes New Roman鈥 might lead to higher rejections and lower casting yield. Further any changes and modifications to be incorporated to the die design, involves metal cutting and reshaping. Computer simulation procedure based process development and die design can be used for rapid process development and die design in a shorter time. Such a computer simulation based procedure, often using state of the art FINITE ELEMENT ANALYSIS based software systems, can improve the quality and enhance productivity of the enterprise by way of faster development of new product. FEM based simulation software systems help the designer to visualize the metal flow in the die cavity, the temperature variations, the solidification progress, and the evolution of defects such as shrinkage porosities, cold shuts, hot tears and so on. Authors have applied FEM simulation to design and develop a variety of Aluminium gravity die casting processes. The components include a gear casing and a manifold. In this process different options of gating design studied by FEM simulation, and the resultant patterns of solidification are discussed.
Property Prediction with macro micro-modeling and computational thermodynamics
Jianzheng Guo, Mark T. Samonds
Part of the challenge of designing a new alloy is understanding the relationships between the alloy chemistry, the processing, and the final properties of an in-service part made from that alloy. The prediction of local mechanical and thermal properties is possible, to a degree, given knowledge of the microstructure, phase fractions, and defects present in a metallic part. Multi-component micro models of solidification, coupled with macro-scale thermal and fluid flow processing conditions, including macrosegregation, have recently been coupled with computational thermodynamics in a commercial software, ProCAST, to form the basis of this type of prediction. Subsequent solid state transformations through heat treatment can also be taken into account.
CAE Techniques for Casting Optimization
M J Marques, INEGI, Portugal
During recent years the application of some popular commercial software as computer simulation tools has become widely accepted within the foundry industry, leaving the idea of the simulation as luxurious tools. The application of casting simulation has been most eneficial for avoiding shrinkage scrap, imporving cast metal yield, optimize the gating sustem design, optimizing mold fillig and finding the thermal fatigue life in permanent molds. Several case studies demonstrate the benefit of using these tools under industrial conditions. nopwadays, in Finland, the foundries that cover around 90% of the production of the cast machine components use casting simulation as an evryday tool. This paper will demonstrate the application of the ProCAST software. Simulation resulted in gating system and moulding changes that reduced the weight of the total casting from 59kg down to 46kg. Maintaining casting quality the yield has increased by 9%. Some experiments were carried out under foundry conditions to compare the results.
Mould Fill Simulation to Improve the Quality of a Component
T Imwinkelried, H Homberger, Alusuisse Technology and Management Ltd, Switzerland
High pressure die casting of large magnesium components is a very cost competitive technology for light weight designs. As many functions can be integrated into a single part, significant assembly cost can be saved. Besides the weight savings, dealing with a single integral part can be of particular interest for a given application. For an instrument panel, the high specific stiffness, the resulting damping characteristics, the excellent mass tolerances are such advantages as well as the absence of rattling noises which can be a nuisance with assemblies. The production of large high quality magnesium components requires high competence with regrad to mould construction, metallurgy and die casting technology. Numerical simulation of mould filling and solidification is an invaluable method to the construction engineer as the complexity of the interactions during mould filling goes beyond human imagination. These simulation tools have become a powerful mean in identifying defects and for the optimisation of moulds.
Application of Numerical Modelling in SSM Automotive Brake Calliper Castings
N Jahajeeah, R Bruwer, O Damm, L Ivanchev, P Rossouw, K Sharma
National Product development Centre, CSIR, South Africa
Numerical modelling has successfully been used as an efficient tool to convert a gravity cast brake calliper to a thixocasting process. The thixo-module of ProCAST has been used for the modelling process to obtain optimal processing parameters. Results from interrupted shot castings show excellent correlation with the fluid dynamics and flow pattern of the model. The level and location of porosity revealed by non-destructive x-rays and microscopic analyses showed good correlation with the model prediction.
Investment Casting Simulation
M Gaumann, A. Sholapurwalla, ESI Group
In the current environment, investment casters need to stay on the cutting edge of new technologies to remain competitive in the marketplace. The capability to produce investment casting components of high quality while at the same time reducing product costs and development times is the challenge the foundry industry faces today. Increasingly complicated parts are being made through the investment casting process with less castable alloys. Computer aided modelling has been helping the foundry industry for the past several years, not only with the design of new components, but also in the redesign of existing products. By eliminating product defects and reducing scrap and rework, the investment caster can achieve improvements and more consistent product quality and obtain higher yields.
Simulating the Lost Foam Casting Process
A Paine, M Gaumann, M Gremaud, ESI Group
Throughout the manufacturing industry, process simulation software has been accepted as important tools in product design, process development, improving yield and in solving processing problems. The lost foam casting process, also known as the evaporative pattern process, involves casting liquid metal into a non-vacant sand mould filled with a combustible polymeric material. The foam disappears as the molten liquid enters the mould, causing the progressive burn-out of the foam pattern. The metal precisely replaces the foam pattern to form an identical geometric copy of the pattern. Although there has been a rapid increase in the use of the lost foam casting process (LFC) world wide, there has also been extensive research work allowing more understanding of the process which, even though continued RD effort is needed, this has allowed the development of accurate and predictive lost foam simulation software. Along with the large benefits associated with lost foam casting there is also the increased risk of producing defected components due to the strong requirement for precise process control. Thus, in order to get a good understanding of the process, there has been a strong drive from industry to produce mathematical models which are used to accurately simulate the lost foam casting process. The complexities associated with modelling this process, which involves numerically coupling the heat transfer, the fluid flow, the foam evaporation and the gas transport, makes this certainly one of the most challenging processes to simulate. Various industrial cases are presented in the paper showing applications of the simulation software ProCAST in lost foam casting. |
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