Hot sand is produced with the systematization and speeding up of the casting line and is causing various problems. The relationship of compression strength, permeability, compactability and surface stability to sand temperature under various conditions was clarified, and variance of the properties of the hot sand when left to stand for given periods of time in air was also determined. A laboratory mixer was improved to enable high precision mixing of hot sand of the desired temperature. It was comfirmed that there is almost no change in the properties of the sand itself, but it was found that care must be taken because the values of permeability and compactability, when dealt with by the usual method, turn out to be altogether different from what they really are. Further, the importance of sand control from the time of mixing until molding has been confirmed, for, when the hot sand is left to stand in air, the variance becomes great, especially when the moisture is low (less than 3%) due to elevation of the temperature of the sand and prolongation of the time it is left standing.

View full abstract

  The temperature of eutectic growth front in unidirectionally solidified cast irons and their graphite structure were investigated in the range of growth rate from 0.32 to 25μm/sec. The eutectic growth temperature was lowered by increasing growth rate, and raised by increasing silicon content. The eutectic with coarse flake graphite grew at low growth rates, whereas fine undercooled graphite eutectic structure appeared at high growth rates. The transition of coarse flake-fine undercooled graphite structure occured at growth rates around 4μm/sec and almost independent of silicon content. The equillibrium eutectic temperature rose linearly with the silicon content at the rate of 3.2°C per percent silicon from 1,154.5°C of pure iron-carbon eutectic temperature. The undercooling of the eutectic growth front was nearly proportional to the square root and cube root of the growth rate in coarse flake graphite and in fine undercooled graphite structure. The transition of coarse-fine undercooled graphite structure was explained in terms of the relationship between the eutectic growth temperature and growth rate.

View full abstract

  Packing particles in a permanent mold and forcing melt to flow into the interspace among the particles by pressure casting is considered to be one of the most convenient methods of producing metal-particle composite because of the simpleness of the principle and the procedure of manufacture. In order to clarify the relation between the particle preheating temperature and the length of the composite products, melt of tin, lead or zinc, which was free from superheat, was forced to infiltrate the spherical particle aggregate of glass, copper, lead or carbon, which had been preheated at various temperature, by an oil press. Any combination system of metal and particles has a unique particle preheating temperature, i.e., the critical temperature, only above which the melt can flow long enough to fill out the mold. The liquid volume fraction at the critical temperature, i. e., the critical liquid fraction, was from 0.30 to 0.49. The critical preheating temperature can be expressed in terms of some physical constants of the metal and the perticles and the critical liquid fraction.

View full abstract

  It is known that in using foundry dust as asphalt filler for pavement material, when the dust is contaminated with sodium silicate stability against water becomes poor but that it can be improved by adding slacked lime. This is a study made to clarify how slacked lime improves the stability and to quantify the amount of addition necessary as a commercial standard.

View full abstract

  Thermal diffusivity of Vacuum Process mold, dry sand mold, furan resin bonded sand mold and phenolic resin bonded sand mold, which contained less than 0.5 percent water, was obtained within 5 percent dispersion. That of the molds containing more water such as green sand mold, CO₂ mold and plaster mold was also determined within 10 percent dispersion from temperature distribution in the dry zone. Chilling power of mold could be expressed by apparent thermal diffusivity taking moisture movement into consideration. The solidification time calculated by these obtained thermal properties coincided well with the measured value.

View full abstract

  Manganese in liquid high manganese cast steel volatilized and mostly penetrated through the serpentine and the cracks in the olivine sand. The penetrated manganese lowered the melting point of the surface of the olivine sand, and a smooth shell (semi-fused layer) was formed at the metal-mold interface. After cooling, the shell easily peeled off from the metal and had no-burning as a result of low affinity. The same reaction was seen both in green and calcine sand, but as the green sand was dehydrated and the mold cooled, the shell of the mold was thinner than the calcine one. Calcine sand may cause neither blow hole nor pin hole, but the dehydrated gas from green sand will cause blow hole and pin hole when the mold permeability is not sufficient.

View full abstract