Under this heading only the hand tools and equipment used by the molder in putting up his mold are described. The mechanical appliances for reducing labor are described in a later section.
To use sand economically for molds, sets of open frames called flasks are used. Flasks consist of two or more such boxes. The lower box is called the drag or nowel, the upper box is called the cope. If there are intermediate parts to the flask they are called cheeks. Flasks are fitted with pins and sockets so that they will always register.
For small castings the molds are rammed up on benches or projecting brackets. Such work is termed bench work and the flasks are usually what are known as snap flasks. They range in size from 9 by 12 inches to 18 by 20 inches. As is seen in Fig. 1, these flasks hinge on one corner and have catches on the diagonal corner. The advantage of the snap flask is that any number of molds may be put up with but one flask, and the flask removed as each mold is completed. There are several good snap flasks to be had on the market. Many foundries, however, make up their own.
Each size of flask should have at least one smooth straight board called the mold board, the size of outside dimensions of the flask.
Rough boards or bottom boards of same size should be provided, one for each mold that will be put up in a day.
Boards for snap work are made of from 3/4 to 1-inch stuff, and should have two stiff cleats, as shown in Fig. 2, to hold them straight Wood Flask. For heavier castings where the molds are made on the floor, box flasks are used made of wood or iron.
In the jobbing shop, wood flasks are more economical, as they can more readily be altered to fit a variety of patterns, while in a foundry turning out a regular line of castings, iron flasks pay because they require less repair.
Wooden flasks of necessity receive hard usage in the shop and grow weaker each time they are used. They will burn more or less each heat; they receive rough usage when the mold is shaken out; and often the flasks must be stored where they are exposed to all kinds of weather. It is economy, therefore, to build wooden flasks heavier than would be necessary if they were always to be used in their new condition.
Fig. 3 shows the construction of a typical wooden flask; the sides project to form lifting handles; the ends are gained in to the sides. Through bolts, in addition to the nailing, hold the sides firmly. A detail of the pin is shown at A, and at B is a cast-iron rocker useful on flasks over 4 by 5 feet, to facilitate lifting and rolling over. The cleats make it a simple matter to alter crossbars. The crossbars should be not over 8 inches on centers. For more than 3-foot spans they should have short crossbars through the middle connecting the long ones. In flasks 4 feet and over there should be one or more iron crossbars and a 1/2-inch through bolt with good washers to clamp the sides firmly to them.
(6 inches deep)
Up to 24 by 24 in.
18 in. to 24 in. wide up to 5 ft. long
24 in. to 36 in. wide up to 6 ft. long
36 in. to 48 in. wide up to 7 ft. long
Note. For each additional 6inch depth of copo or drag add 25 per cent to the thick.
Table II shows thickness of stuff for sides and crossbars for average sizes of jobbing flasks.
Find thickness of sides and bars in a flask 30 by 48 inches.
By referring to Table II, it is noted that for lengths on the sides over 2 feet and under 5 feet the thickness of sides should be 2 inches.
Similarly, for widths of flask of over 24 inches and under 36 inches, the thickness of crossbars should be 1 1/4 inches.
In Fig. 4 is shown the construction of a large iron flask suitable for dry-sand work. The pieces of the flask are usually cast in open sand from a skeleton pattern, all holes cored in. The crossbars are cast in the same way; they have a slot in the flange instead of holes to facilitate adjusting them. Trunnions and rockers are sometimes cast on the sides in a core instead of being made separate and bolted on. Holes for pins are usually drilled through the joint flange. For pins, short iron bars are used temporarily in closing. The thickness of metal varies from 7/8 inch to 1 1/4 inches, according to size of flask.
Fig. 4. Iron Flask.
In Fig. 5 is shown a typical form of iron flask used on some molding machines. The boxes are cast in one piece. The handles-serve as lugs for the closing pins. Only one pin is fixed on each box. This makes the boxes interchangeable and capable of being used for either cope or drag.
For cutting and handling loose sand the molder uses a shovel with flat blade, as in Fig. 6, for it is often more convenient to let the sand slide off of the side of the shovel than off of the end.
Fig. 6. Flat Marie Shovel.
This is especially true when shoveling sand into bench molds or molding-machine flasks.
The foundry sieve or riddle, Fig. 7, is used to break up and remove lumps, shot iron, nails, etc., from the sand placed next the pattern or joint. Sieves should have oak rims with brass or galvanized-iron wire cloth.
In ordering, the diameter of rim and the number of meshes to the inch of the woven wire is given. Good sizes for the iron foundry are 16 inches to 18 inches diameter, No. 8'to 12 on bench work, No. 4 to 8 on floor work.