While many studies have been reported on the properties of casting sand by sand test pieces, after-treatments of moulding sand such as washing have not yet been fully considered
The aftertreatments may be usually applied to green sand or to skin drying mouldings in steel castings, but the reports of the effects of washing to mould surfaces have been scarcely reported to the present.
  So, the author investigated the varions changes caused by washing in steel casting mould surfaces.
  The results obtained are as follows;
  (1) Cracks are caused by washing over the constant quantity (cc/cm²) on moulding sand surface when the sand contracts in constant rate of drying. Especially the intensity of cracks should be large in the non-fixed areas of mould surface layers. The foundry men may consider the possibility that scabs in steel castings are caused by these cracks.
  (2) To some constant sand mixing, the intensity of cracks is proportional to washing quantity (cc/cm²).
  (3) With the excess washing, cracks parallel towards mould surfaces are generated first, vertical ones such as on the boundaries in metal structures next.
  (4) Washing of less moleculer weighted solute solution increases the intensity of cracks.
  (5) The more the washing increases, the less the loss of sand in scraching test decreases.
  (6) The more the sand is coarse, the less the intensity of crucks decreases.

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  In the case of horizontal centrifugal process, it is important for small steel castings, with higher melting point and solidification than rate iron castings, that the determination of pouring rate in the practical operation.
  The pouring rate relates to the factors, inner diameter of castings, pouring weight and temperature, nose shape and inclination degree of trough.
  In this report, the nose shape and inclination degree of the trough is decided from the study on the mutual relation of pouring weight, inner diameter of castings and pouring time. And the results are follows:
  (1) Inclined degree of pouring trough (θ) is found suitable between 20°∼25°.
  (2) The better trough cross section is found to be round independently with the size of casting inner diameter.
  (3) The curve of pouring rate is given by exponential function, Ƭ=C·Wⁿ and it changes with the pouring weight.
  Moreover, author confirmed that these results are sufficiently utilized in practical operation.

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  Numerous problems related to equipment and casting techniques were encountered in carrying out a continuous flow of operations by the shell mould process from one pouring on a conveyor to shakeout, trimming and blackenig of approximately 100 different kinds of automotive parts, whose weights as-cast range from 0.04kg to 47kg.
  In the layout of shop facilities, consideration was given to effect an arrangement of highly effecient equipment and to utilize the length and width of the shop with the aim of accomplishig high productivity. This resulted in (1) the adoption of the vertical pouring system on all parts in order to perform wasteless pouring of continuously tapped molten metal, raise productivity within a limited floor space and improve quality, (2) setting up of a control center so as to enable a smooth pouring operation for a combination of parts of varying sizes, and (3) equipping a direct reading spectrometer to control the molten metal for parts of varying material quality and thickness.
  On problem related to the quality of castings, for instance, (1) the internal defects of the water-cooled cylinder head was eliminated by improvement of the gate ratio and the adequate control of the pouring temperature and speed in the casting plan, and (2) defects arising from dross formation on the ductile cast iron crankshaft inherent of such metal have been eliminated by controlling the pouring temperature, carbon equivalent and the amount of Mg additives. As with defects arising from shrinkage cavities these proved effective.
  With foundry setup and casting technique mentioned, a striking advance in production has been observed, and production in terms of cast iron output in 1961, after installation of equipment, increased 2.7 times per square area and 2.2 times per man, as compared with that of 1956.

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  So many theories for the formation of spherulitic graphite in ductile cast iron have been proposed, and thereby we have deepened our understanding of this form of graphite. Spherulite is well known among mineralogist and the spherulites of many organic and inorganic compounds were refered to with respect to the formation of spherulitic graphite in cast iron. A spherulite named “nodular troostite” in steel has been also well known among metallurgist. The nodular troostite is formed when high carbon steel is mildly quenched where A₁ transformation is depressed from 60°C to100°C under 723°C of normal eutectoid transformation point of Fe-C alloys.
  The present research was undertaken to study the noduralization of graphite in Ni-C and related Fe-Ni-C alloys, where no carbide is introduced, in their structune as in the case of cast iron, where double equilibrium γ and Fe₃C in one side and γ and graphite in the other are comming into coexistence. In Ni-C alloys the graphite spherulite is simply formed when thery are melted in CO gas atmosphere and then cast in steel mold, where the eutecic point of 1318° is under-cooled to a temperature of 1285°, without any addition of magnesium.
  Ni-C alloys having eutecic or slightly hyper eutectic composition were used as base metals. They were produced in alundum crucibles, using electrolytic nickel and pulverised charcoal under the cover of a mixture of calcium carbonate and charcoal powder. They were melted in a glover type electric furnace, heating up to a temperature of from 1550° to 1600°C, and then remelted again under the similar condition to get possibly homogeneous alloys. About 20 grams of these alloys were melted in the same furnace without covering flux in a smaller Tammann tube made of alumdum or of carbon electrode, embeded in charcoal powder retained in a some-what larger crucible. Within a few minutes they were molten and attained a temperature of 1550°C, where they were held 2 min. and cast in various molds, i.e. baled core mold, green sand mold, steel mold and copper mold of the same dimension. Thermal analysis of these catings were made with an electro-oscillograph, and the depression of eutectic freezing point and the structure of each castings were observed. Thus we confirmed that melts in the steel mold have an undercooled eutectic point at 1285°C, having a super cooling of 33°C, and complete spherulitic graphite structure all over the specimens.
  The influence of the addition of third elements on the graphite structure were then studied. An addition of manganese up to 2% and silicium up to 1% respectively have no influence on the form of graphite nodules. The influences of calcium and magnesium were then studied. The addition of these elements shew the structure consisting of larger nodules provably fo primary graphite and small nodüles provably of eutectic graphite. Besides they have no influence on the graphite stucture as the residual calcium content is less then 0.12% and the residual magnesuim content is less than 0.098%.
  The addition of titanium up to 0.15% was effective for the refinement of graphite nodules. With titanium content over 0.15%, the structural change was apparent owing to the formation of titanium carbide eutectic. Finally we studied the effect of iron, adding Fe-C eutectic alloy to Ni-C alloys. Up to 10% of iron the graphite structure was not changed, but if the iron content was increased over 10%, the graphite structure changed gradually forming incomplete nodüles and finally all flaky graphite of on alloy containing 50% of iron.
  From all these experiments the neccessary conditions for the formation of spherulitic graphite in Ni-C and Fe-Ni-C alloys may be summerised as the following.
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