Metal casting by the sand mold


"Sand molds" is a fundamental method to the casting of most ferrous metals and many nonferrous metals.

<Making a sand mold>

Some tools used in sand molds are prepared(flask,rammer,riddle,etc.). Also, enough sand should be prepared to fill the flask. The sand is mixed with the water glass (NaO.nSiO2.mH2O) previously.

1. Filling the molding sand to the wooden flask.

As first, the molding sand is filled into the lower flask, and an objective pattern is put down in a central location on the molding board. An upper flask put upon the lower one together with some parts to make the down gate and the gas vents , and filled with the molding sand completely.

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2. Ramming around the flask.

Ramming arround the flask is done with a peen or the wedge-shaped end of the rammer.

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3. Scrape off the remainder

The remained sand is scraped off, and many small holes are opend to prepare the next mold hardening step.

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4. Hardening the sand mold.

The molding sand mixed with the water glass is hardened by CO2 gas. Chemical reaction is shown as follow; Na2O.nSiO2.(mn+x)H2O+CO2 = Na2CO3.xH2O+n(SiO2.mH2O).

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5. Removing the wooden flask.

After hardening the molding sand, the wooden flasks are removed mechanically.

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After removing the flask, surface of the mold is smoothed, and then the objective pattern (dumb-bell in this case) are removed.

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6. Several sand molds manufactured in this work.

Three kinds of the sand molds are manufactured in this work.
upper; fluidity test pattern
lower; wind bell
left; dum-bell

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< Melting and Mold pouring >

1. Melting the iron source.

lron source is melted to liquid state by "High frequency electric induction furnace".
The temperature of molten iron is over 1500 deg C.

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2. Pouring the molten iron to the mold.

The moltem metal is tranfered from the furnace to the mold using a pouring ladle.

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3. The scene of the fluidity test.

This figure shows the scene of the fluidity test which is need to obtain the castings of substandard quality.

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< Get the sand castings >

1. Get the castings from the sand mold.

To get the sand castings, the sand mold is broken by a hammer when a poured iron cool to room temperature.

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2. Example of the sand castings.

A wind bell and the sand molds are shown in this figure.
The wind bell is a traditional summering goods in japan. It is hung under the eaves, and tinkling with a cool tone.

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