Modeling and Simulation of Heat Transfer Phenomenon Related to Mold Heating during Investment Casting
- 1 Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore, Pakistan
- 2 Eastern Engineering Solutions LLC, Detroit, MI, USA
- 3 College of Engineering & Emerging Technologies, University of the Punjab, Lahore, Pakistan
Abstract
Cast shape during investment casting process dictates properties and service life of the casting. These properties are the function of cast part parameters (both static and dynamic), part geometry and hence mold geometry, nature and type of metal being cast, properties (extrinsic and intrinsic) and processing parameters (rate of heating, rate of cooling, rate of pouring). Improper and inadequate manipulation and modification of mold properties degrade the properties and life of casting altogether. A mathematical model is developed using standard transport equations incorporating all heat transfer coefficients (HTCs) to determine the effect of external mold heating on the properties of the final casting and a simulation is performed in C++ to validate it against experimental results. Pure iron is casted in investment molds of silica sand with zircon coating. Airflow near the mold surfaces was partially restricted due to geometry of the molds and arrangement of the pieces around a tree. The variations in heat transfer coefficient contribute towards total heat transfer out of mold surface. External heating is found to be very effective for improved casting properties. The mold heat transfer profile is found to be in good agreement with experimental values validating the effectiveness of mold heating.
- Taylor, H.F., Flemings, M.C. and Wulff, J. (1962) Foundry Engineering. John Wiley and Sons, Hoboken.
- Heine, R.W., Loper, C.R. and Rosenthal, P.C. (1967) Principles of Metal Casting. McGraw-Hill, Boston.
- Poirier, D.R. and Poirier, E.J. (1998) Heat Transfer Fundamentals for Metal Casting, with SI Units. Wiley, Hoboken.
- Sabau, A. (2005) Numerical Simulation of the Investment Casting Process. Transactions of American Foundry Society, 113, 407-417.
- Pehlke, R.D., Jeyarajan, A. and Wada, H. (1982) Summary of Thermal Properties for Casting Alloys and Mold Materials. NASA STI/Recon Technical Report N, 83.
- Sabau, A.S. and Viswanathan, S. (2004) Thermophysical Properties of Zircon and Fused Silica-Based Shells Used in the Investment Casting Process. Transactions of the American Foundry Society, 112, 4-81.
- Gebelin, J.-C. and Jolly, M.R. (2003) Modelling of the Investment Casting Process. Journal of Materials Processing Technology, 135, 291-300. https://doi.org/10.1016/S0924-0136(02)00860-9
- Givler, R.C. and Saylors, D.B. (2000) Efficient Runner Networks for Investment Castings. International Journal for Numerical Methods in Engineering, 48, 1601-1614. https://doi.org/10.1002/1097-0207(20000820)48:11 3.0.CO;2-0
- Upadhya, G.K., et al. (1995) Modelling the Investment Casting Process: A Novel Approach for View Factor Calculations and Defect Prediction. Applied Mathematical Modelling, 19, 354-362. https://doi.org/10.1016/0307-904X(95)90001-O
- Konrad, C.H., et al. (2011) Determination of Heat Transfer Coefficient and Ceramic Mold Material Parameters for Alloy IN738LC Investment Castings. Journal of Materials Processing Technology, 211, 181-186. https://doi.org/10.1016/j.jmatprotec.2010.08.031
- Dong, Y., et al. (2011) Determination of Interfacial Heat-Transfer Coefficient during Investment-Casting Process of Single-Crystal Blades. Journal of Materials Processing Technology, 211, 2123-2131. https://doi.org/10.1016/j.jmatprotec.2011.07.012
- O’Mahoney, D. and Browne, D.J. (2000) Use of Experiment and an Inverse Method to Study Interface Heat Transfer during Solidification in the Investment Casting Process. Experimental Thermal and Fluid Science, 22, 111-122. https://doi.org/10.1016/S0894-1777(00)00014-5
- Zhang, X.P., Xiong, S.M. and Xu, Q.Y. (2006) Numerical Methods to Improve the Computational Efficiency of Solidification Simulation for the Investment Casting Process. Journal of Materials Processing Technology, 173, 70-74. https://doi.org/10.1016/j.jmatprotec.2005.09.030