After the castings have been poured the sand is usually shaken off from the heavier parts so as to produce an even cooling as already stated. The pouring is usually done at the close of a day's work. When the sand is shaken off, the sprues are broken from the casting by the blow of a hammer., The cleaning is done the next morning. This consists in removing the sand that may adhere to the surface of the castings, and taking the cores from the inside. There are three methods of removing the sand: by rattling, by brushing and by the sand blast. The first is used for small castings. They are put into a cylindrical shell, which is slowly revolved. The castings are thus tumbled over each other. As they rub and strike together the sand is removed and the surface of the castings made smooth and bright.

The brash is made of strong steel bristles, These remove the sand From the surface of the casting. The brashes may be used by hand of be driven by power. This is the most common method of cleaning castings.

The sand blast is used upon heavy castings. It consists of cutting off the adhering sand by a stream of sand impelled by a current of air; Care must be exercised in using the sand blast as the sand has very great abrasive power. If allowed to strike against the net of the casting it will cut it away. and groove it deeply.

Cleaning Castings 100416

Fig. 42.

The sprues that are knocked off from the castings are usually thrown into the rattler with the shot and fine iron left in the debris from dumping the cupola. After these have been cleaned they are again thrown into the cupola and melted as scrap.

Shot is the term applied to the small pieces of metal found in the cupola damp, They are usually hard and are similar to a high grade of No. 3 iron. Scrap is the metal that is thrown aside and is useless except it be re-melted and re-worked.