EMBOSSING OR COINING DIES.
Embossing or coining dies, for coins or jew elry work, are used for striking up coins, med als, emblems, or other work that has to show the imprint and the figures which are cut in the die. Their manufacture is termed die sinking. In the case of dies used for coin work, both the upper and lower die are embossed or engraved with the design or letter work that it is desired to have stamped on the coin; the blank being fed on to the lower die, which is surrounded by a knurled ring, and as the upper die or punch descends, the metal is confined and kept from spreading by the ring.
Dies used for coining are the oldest example of die work that we have any knowledge of as there are in existence a number of coins which were °struck up° over two thousand years ago; showing plainly that the art of die-sinking was known at that period, but the fact that they were left untrimmed or rough, on the edges, indicates that the process of punching by means of a close-fitting punch and die was not known at that time. Dies for coining could have been used in a press of very rude construction, the main requisite being that sufficient power was employed on the upper die or punch, to leave the desired impression upon the coin. This
may have been done by the use of an ordinary maul or sledge, the upper die being held by hand. Coining dies are the highest example of the die-sinker's art.
Embossing Dies for Jewelry Work.— In jewelry dies the impression is usually cut or thubbed° into the lower die, and the male die or aforce as it is called, being used to drive the metal into the lines drawn or cut, so as to bring up the desired design. Dies of this class are used to produce almost every known form of jewelry work. The back of a watch or locket, being a familiar example. Spoons, knives and forks, and in fact almost every article of tableware, are formed by the above method.
Hydraulic Dies.— Embossing is often done on very large pieces of work, especially on what is known as hollow-ware, such as ice pitchers, etc., the blank being placed in the die, which is sectional and then put into, the press. The blank is filled with water or some times a special composition of wax, which is then subjected to a very heavy pressure, forcing the pitcher or other work into the desired shape, and also into the lines which are sunk or cut in the dies.