Computer simulation has an important role for various industrial processes. In casting, many phenomena such as fluid flow or solidification are calculated by computer simulation. However, it is quite difficult to simulate them integrally, because these phenomena complexly interact each other. Therefore, to estimate shrinkage or other defects, we have no other way than using special techniques such as Niyama criterion, indirectly. Recently, a simulation program with new approaches based on lagrangian method is developed. It is named particle method. Particle method can couple various simulations such as fluid flow, solidification, and structure analysis. Then, it is possible to calculate shrinkage, shrinkage flow, and deformation, directly. In this study, heat transfer and solidification analysis using particle method is examined as the first step of coupled simulation. As a result, it is confirmed that the program using particle method has equal quality as that using finite volume method.

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  The strength of ceramic shell is very important for our ceramic process, which does not supported by back sand. We already reported that the most suitable refractory material for the ceramic mold is a 1 : 1 mixture of zircon and fused silica. The purpose of this paper is to present the relationship between the distribution of particle size of ceramic powder and strength of the ceramic shell.
  The bending strength increases with the coarse particle size ratio when the ratio is below 80%. The maximum values occur when the particle size ratio, namely COARSE : FINE is 80 : 20. This result suggests that the most preferable mold is made by the ratio, coarse 80% ; fine 20%.
  The maximum filling of the particle can be expressed by entropy of the particle size ratio by the equation V_mix ＝ ΣV_iX_i ＋ kΣX_i ln X_i In which the apparent volume of suspensions become minimum when the ratio of coarse particle is 80mass%. The thickness of ceramic shell layer increases with the coarse particle size ratio. On this basis, we developed the ceramic mold process without back-up sand to produce various stainless steel castings.

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  In order to achieve high-strength ceramic shell mold, the production of suitable ceramic shell is very important. We have already discussed that the most suitable refractory materials were 1 : 1 mixture of zircon and fused silica particles. The aim of this paper is to make clear the relationship between the particle size distribution of refractory materials and the apparent viscosity of slurry on ceramic shell mold.
  Two kinds of refractory materials, fused silica particles and zircon particles, were used for the slurry, and colloidal silica was used for the binder. #100 and #350 of the particle size of each refractory material were tested. The six different particle size distributions were set. Three concentration levels of slurry were prepared by changing the fraction of filler and binder.
  When the weight fraction of the coarse particles was less than 0.6, the apparent viscosity of the slurry decreased with increasing the weight fraction of coarse particles. The minimum apparent viscosity was obtained at the weight fraction of coarse particles was between 0.6 and 0.8. The apparent viscosity of the slurry good agreed with the semi-theoretical equation η_s ＝ η₀ {1 ＋ 3 / (Φ_V^－1 － Φ_VC^－1)}, where η_s : apparent viscosity of slurry, η₀ : viscosity of colloidal silica binder. Φ_V : volume fraction of refractory materials Φ_VC : maximum volume fraction of refractory materials obtained from the experiment.

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  In order to clarify the quenching crack phenomenon in cast steel, a disk shaped low alloy cast steel specimen with an opening was quenched in polymer at 1123K. The behavior of quenching crack was checked by microstructure observation and analyzed by heat treatment simulation. Influence of the polymer density on the cooling process of low alloy cast steel materials was greatest in stages I and II of the cooling process. Transformation stress on martensite also has great influence, and qunching crack occurs less easily with decreasing martensite transformation rates. Heat treatment simulation clarified the causes and differences in mechanism for quenching crack. In addition, heat treatment simulation was also useful for predicting crack generation time and crack generation position in the specimen.

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