Numerical Simulation Of Gray Iron Of Lost Foam Casting Process

Lost foam casting （LFC） as a precision near net shaping technology, with it’s manyadvantages, is known as "green casting technology for the21st century", and has abroad prospect of application.In mold filling process of lost foam casting, the gas produced by the decompositionof foam pattern has an important influence on liquid metal filling behavior. Accordingly,velocity field, the free surface shape, temperature distribution in solidification and thedefects introduced from mold filling and solidification process for lost foam casting aredifferent form traditional sand casting. The numerical simulation method can effectivelyreveal the filling rule of liquid metal and interaction mechanism of foam-liquid metalduring LFC process, and also predict the defects in the castings. Therefore, a theoreticalguidance is provided for the optimization of the casting process design and improvingthe quality of the castings.In this work, according to the characteristics of lost foam casting technology,three-dimensional geometry model of a plate-type gray cast iron casting was built byusing UG program and the process of mold filling and solidification in LFC wassimulated using ProCAST program. The influence of various technical factors on themetal front velocity, the pressure in gas gap and gas gap thickness and the metal fronttemperature in lost foam casting process were discussed. The main conclusions are asfollows:1、 The mold filling velocity of liquid metal increases with increase of the pouringtemperature, vacuum and coating permeability, and decreases with increase of thepattern density and thickness of coating.2、The thickness in gas gap and pressure gas gap increases with increase of the pouringtemperature, the pattern density and thickness of coating, and decreases with increase ofvacuum and coating permeability. 3、Metal front temperature decreases with increase of the foam density and the thicknessof coating, but increases with the increase of vacuum.4、Through the simulation, the relatively reasonable parameters are obtained forplate-type gray cast iron castings: pouring temperature of1400℃, foam density of13kg/m³, vacuum of0.04MPa, coating thickness of0.5mm and coating permeability of9.5×10^-9m²/Pa.s.On the basis of the above works, the lost foam casting process of the box cap andscaleboard was designed. The mold filling and solidification process of the castingswere simulated, and the casting defects were predicted. And then the correspondingprocess optimization was carried out. The sound castings are obtained according to theoptimized technical parameters. It proves that the numerical simulation method in thiswork is reliable.