Moulds of these two classes are made in flasks of various shapes and sizes. Wood or iron flasks are used for green sand molds and cast-iron flasks are used for dry sand and steel moulds.

Fig. 120 shows three flasks extensively used for small moulds. Each of these consists of three parts - cope, drag and bottom board. Suitable lugs and pins are provided to insure the cope and the drag going together always in the same relative position. No. 2 may be poured from the top, or may be set on end and poured through one of the holes in the end to insure a better metal pressure in the mould. No. 1 is a snap flask, which may be removed from a mould and used for making other moulds of the same size. When this flask is removed, a rectangular box is slipped over the mould in its place to support the sand. No. 3 is for general use for small moulds. Each size of small flasks for general use should be made interchangeable, i. e., the upper part of any flask should fit the lower part of any other flask.

Fig. 120.   Small Moulding Flasks.

Fig. 120. - Small Moulding Flasks.

Fig. 121 shows two flasks for medium-sized moulds. The weight of sand in the cope is too great to hold in place without the cope bars B. The drag needs no bars, but it must have a bottom board if it is to be turned over in the course of making the mould.

The upper view shows a three-part flask for a pattern which cannot be removed from a single parting in the two-part flask. The cheek, or middle part of the flask, also has bars. These extend radially from corners and sides of the cheek toward the pattern, but bars should not be within less than about 3/4 inch of the pattern surface.

Many cast-iron flasks are shown in the view in Fig. 119. They are made up of flat cast-iron sections bolted together, or of round sections made in one piece. A large cope is shown at C with rods and bars arranged for a particular casting. A circular cope and drag clamped together are marked B and D. Each of these parts has a pair of trunnions by which it may be suspended and revolved while giving the mould its finishing touches.

Several minor devices are used for assisting cope bars to hold a body of sand firmly in place. Nails are frequently driven along the under edge of a bar to hold projections of sand in an irregularly shaped parting. Bent iron rods, called gaggers, are imbedded in the sand to anchor the unstable parts to the firmer bodies of sand in a cope or a cheek. Small tapered sticks, called soldiers, are used when the mould is delicate and cannot stand the weight of gaggers.

258 Flasks For Green And Dry Sand Moulds 140Fig. 121.  Moulding Flasks.

Fig. 121. -Moulding Flasks.

Loose nails are often imbedded in corners of sand or are stuck in the surface of a mould to hold the sand firmly against breaking or wearing away by erosion. Gaggers, nails, etc., are wet with clay water to make the sand stick to them. 16