DIES AND DIE-SINKING (OF. de. det, Fr. de, Sp., Port. It.. (bolo, die. from Lat. dotes, p.p. of dare, to give). The art of making and using dies for stamping coins is of very ancient origin. Old coins have been found which show that it was known to the Greeks at least B.C. SOO. The use of dies for stamping. shaping. and cutting out metals and other materials is of much more recent "right. and renehed its present develop ment only in the closing years of the last cen tury. The use of the punch and press for cut ting metal forms is said to have been practiced in a t rude way by a German blacksmith of the fifteenth century. Presses for shaping as well as cutting metal were invented by T. Grif fiths, of England. in 1841. but they were de veloped in France. where they were ap plied to the production of kitchen uten sils. Recently presses have been utilized in many other brandies of manufacture besides those dealing with metals. The use of dies. for instance, plays an important part in the modern shoe factory, and, in fact, in all indus tries where a given form has to be produced repeatedly, whether the material be metal. leather. cloth, or paper. The most recent de velopment in the art of using dies has been in the direction of working cold steel into numerous complicated form,. which were formerly pro duced only by casting and forging.
The astonishing cheapness of numerous sheet metal products is mainly due to the nse of dies, which accomplish. by a single stroke, the work which formerly required long and tedious manip ulation. A striking C.NallIple is the modern bieyele, a large proportion of whose hundred parts are formed by the power press. Not only kitchen utensils, but jewelry. boxes. pens. but tons. and the thousand and one familiar objects which were formerly worked into shape with the hammer, or soldered together out of separate piece-. are now struck between two dips of suit able form.
Dies. in general. are in pairs, consisting of a male die or punch. and at female die. which are so adjusted on a power press that one fits :teen rately into the other. Often. however. in matting the less resistant materials., as leather, cloth, or paper, the two parts of the typical die are not required. The punch is simply forced by a power hammer through the materials, against a fiat surface. In an article in the Engineering Ilaga7.-ine (New York) for March, 1S9S% on "The Development of Machinery for Sheet - Metal `tamping," Oberlin Smith divides the kinds of work by stamping into four general classes: "( ) Cutting. in which are included punching
and shearing; (2.) forming. including bending, embossing, and curling: (3) drawing and re drawing. which are more than forming, since the metal is subjected to an extensive distortion or molecular flow, incident to the changing of a flat, annular disk into a cylind rical. or conical, or hemispherical form of smaller average diam eter, its surface being meanwhile rigidly ton tine(' to prevent wrinklings: (4) coining. With which should be included drop-forging. the metal in both cases being treated as a liquid and ,imply pumped, as it were, into the shape desired, the molecular flow being very great, and the whole object being treated as is a pat of butter or a cake of soap in the molds provided for its new incarnation." The simplest forms of cutting dies are the blanking dies, used for cutting out that blanks from steel, iron, or other material. A sheer edge is given either to the punch or to the (lie. accord big to the work to lie performed. When, as in cutting buttons, it is the blank, that are to be used, the sheer edge is given to the die; but when the hole is the object sought. a, in making rivet-holes in boiler-plates, the sheer is given to the punch. rowpound cutting dies are used for cutting fine work. where the relation of the centre or other holes to the outside must be per fect. as in blanks for watch and clock movements, and sheet-iron disks for the armatures of dyna mos and electric motors. A die has for its upper half a punch set into a die, and for its lower half a die set into a punch; one stroke of the press thus performs the work that would require two or more operations if done on Needle dies are used for punching eyes in needles. The die is made in three pieces. securely fastened together. The centre piece pro jects above the surface of the two side pieces. and into the groove of the needle. Thus the needle is supported %via& being punched. This centre piece has a U-shaped slot, equal in width to the length of the eye of the needle. The press is so arranged that the needle is first stamped and then punched, the speed of the punch at the moment it enters the eye of the needle being very slow.