Définition

• Dies and Diemaking.  Tools for impressing the relief design into a blank during striking and creating these tools by any method – cutting by hand, milling by machine (including pantographic reduction), or by hubbing. Dies are made by creating the cavities and surface contours in a piece of iron or steel. They are used in pairs to stamp a coin or medal, to impress specially prepared blanks (of proper thickness, shape and composition) by pressing both sides of the blank at one time in a press. The blanks are not heated, but struck at room temperature by dies in a process called cold coining.
                                                      
               Outline of Entry                            
        I. Definition & Overview.                          
       II. Dies in general.                                 
           A. Required die characteristics.                
           B. Names of die designs.                        
           C. Names, types of diemakers.                   
      III. History of Dies:                                
           A. Engraving dies in Ancient times.             
           B. Decline of diemaking in Middle Ages.         
           C. Engraving Roller Dies.                       
       IV. Modern methods of creating dies, how made.      
           A. Engrave by hand.                             
           B. Cut reduction punch from oversize            
              model, diesink, add lettering by punches.    
           C. Model entire design oversize, then reduce    
              by die-engraving pantograph.                 
           D. Tracer controlled outline of design, handcut 
              relief and details.                          
        V. Stronger presses require stronger dies.         
           A. Use of tool steel.                           
           B. Lengthening die life.                        
       VI. Coining dies and collars.                       
      VII. Production of dies made by hubbing.             
     VIII. Open face dies for medal striking.              
       IX. Maintenance of dies.                            
        X. Die's afterlife.                                
  Dies are made, as stated, by creating cavities in a piece of metal, but this metal
  must have some unique characteristics. Iron has the property of being able to be hardened or softened at will (by heat treating), with techniques known to ancient metalworkers (since the Iron Age, 1200 bc). For this reason dies have been made of iron for all time. The iron must be able to withstand the constant pounding of striking – metal stress – and be able to with- stand the heat generated by the friction of metal flowing into the cavities. Thus the purpose of dies, to reproduce like items in multiple issue, was best accomplished by making them of iron (and later of tool steel).
  Creating the cavities and surface contours was first done by hand – by hand engraving – for the first coin dies made about 650 bc; dies can still be made this way today. Diemakers learned that a cylinder of iron could be softened (by annealing), and carved by hand with a pointed piece of iron (hardened by QUENCHING). With this pointed instrument (a graver or burin) the diemaker could carve the design into the die. By working the design, in negative or intaglio, into the end of the iron cylinder the design emerged as a cavity to strike a positive impression.
  About a hundred years later the diemaker found that he could carve the design in relief, in cameo (or positive), and then reproduce that positive metal design into metal in the negative. This was done by pressing the hardened metal containing the engraved relief into softened metal, a process we call hubbing today (it was formerly called "hobbing"). The negative impression from this hubbing is a die that could then be used for striking. The positive master could be used again and again to make additional negative striking dies.
  Basic die characteristics.  Obviously, a die must be harder than the blank being
  struck. Also the die must be able to impress into the blank (forming the design), then it must retract. Nothing in the die or design can prohibit this withdrawal – there can be no undercuts in the design, and all relief must have a slight bevel, otherwise the newly struck piece would cling to the die (what a pressman would call a hangup).
  A die must sustain the stress of deforming the surface metal. Metal in the blank must flow into all the cavities of the die and remain there. As metal flows into the con- figuration of the die, the friction causes the die to heat up slightly. The die must sustain this heat as well as the continued stress of the repeated impact and the surface movement of each struck piece. Thus special steels have been formulated to meet these demanding requirements.
  Dies tend to crack where the stress is the greatest: frequently near the rim, or
  steep-pitched relief as lettering. Thus in creating the design an effort should be made, wherever possible, to lessen the stress in any area. A thorough knowledge of steel is needed for every step of diemaking.
  Die design.  The design in the die – the rise and fall of the image – has different names: the artist calls it relief, the sculptor calls it bas-relief, the diemaker calls it the die geography, the layman calls it the design, the numismatist calls it the type. The author submits a term in which all may find a common ground, by calling it: modulated relief, the rise and fall of the image that forms the design.
   
  Die makers.  The first maker of dies was originally called a celature (a carver of glyptic objects), then this diemaker was called an engraver (for hand engraving) then a diesinker (for both engraving and hubbing). Today the maker of dies is called by the machine he operates (a hubber, or transfer engraver, or pantograph operator, or tracer controlled engraver or edm operator). If he engraves a die by hand, as in the past, he is still called an engraver. (But in most literature an engraver is one who does flat engraving for making prints, in contrast, a maker of dies for striking is called a diesinker.)
  Also the term dies includes tooling that does something other than impart a relief design. blanking dies cut out planchets prior to striking. trimming dies shape a piece after it is struck. Much of these tools are compound tooling – often built as a die set – to perform the work required. Thus the concept of dies include the shaping of a coin or medal as well as creating its design. The person who makes this tooling is called a tool and diemaker.
   
  History of Diemaking
  Ancient dies.  The first die engravers accomplished the engraving of a die by picking away at the surface of a block of softened iron until the design emerged. The one great difference from modern engraving was not the tools, but the magnification. It is doubtful the very early engravers used any magnification, but had very good eyes. They did use a glass globe filled with water to concentrate a ray of sunlight to their work area.
  Fine emery was known in ancient times and used for smoothing out the surface and removing tool marks. Proving was done then, as now, by pressing the die at any stage of the work in clay or wax. The engraver continued to pick and smooth the surface until he was satisfied with the design he had created. The die could then be hardened by heat treating, methods known since the beginning of the Iron Age (1200 bc). Dies were made by these primitive methods during the Greek, Roman, and early Byzantine periods (640 bc-800 ad)
              The use of dies in ancient times was by a sledge driving the upper die – called a
  trussell – into a blank laid on the anvil die. The wear to these dies was not equal, the
  upper die, generally the reverse, receiving the greatest stress, breaking more often that the
  obverse. Thus the reverse die being replaced more often gave rise to numismatists later
  studying die-linkage, where several reverses may have been mated with one obverse.
   
  Decline of diemaking in Middle Ages.  The great advances in diemaking, and coinmaking in general, declined after the fall of Rome. Coins became thinner, the reverse design disappeared altogether on some (called a bracteate). Less and less of the design was engraved, and more was made with punches, until the entire design was made with three piece punches. The coins were struck by moneyers who were less concerned for their artistic content than receiving one for every twelve they produced.
  It was easier to strike a thinner blank, particularly with no reverse design, in effect to emboss the thin shell metal rather than to impress a thicker blank. Also the dies were easier to make with piece punches rather than engraved. Punches with pointed ends shaped as lines, blocks, arcs and circles were used in combination to form every part of the design, the device and the lettering, even portraits.
  The resulting design from synthesized piece punches appear quite crude. They lacked the charm of relief, the appeal of minute detail and the execution of sharp-edge designs. The diameter of dies and coins remained small, under one inch. As works of art, they fall woefully short in comparison with the grandeur of the engraved designs of Greek and Roman coins at their finest. Yet dies and coins were made by these crude methods for nearly 700 years.
  Minting was decentralized. Some kingdoms operated as many as 80 mints (as did Spanish King Liuvigild, 568-586, on the Iberian peninsula). It is understandable that coin and die production deteriorated. The responsibility was placed with moneyers whose concern was to produce so many pieces of which they received one of every twelve. Their concern was not the attractiveness of the coin design nor improving the coining process, nor security, only making coins as quick and easy as possible.
  Engraving roller dies.  A new concept of making coins by roller dies (taschenwerke), first created in Germany in 1551, required dies to be engraved on the circular surface of cylinders. A combination of both piece punches and hand engraving was required to produce these dies. Engravers found they could engrave on the curved surface as well as a flat surface of normal dies.
  To create the coins the intaglio roller die was rolled, under pressure, across a strip of metal; the die impressed the design once for every rotation of the cylinder. It was trimmed from the strip afterwards. Larger coins could be made in this manner but several problems existed with the use of these roller dies: the relief was very shallow (lack of pressure exerted by the press), slippage and the problem of trimming and treating the edges after the coin was formed.
  Production was faster and a higher quality coin was produced in the screw press despite the limits of its pressure and the small diameter of coins made by this method. The roller die process fell into disuse by 1651.
  Modern Methods of Die Making
  Hand engraving dies.  Using a burin or graver is the same today as in ancient times. Metal is removed one bite at a time. Gross metal can be removed – as  background cutaway – can be done with a small chisel. Gravers are available in many shapes for specific work. The tools have changed somewhat, made of hard tool steel, they are less likely to break under the pressure of metal carving.
  Metal can be smoothed by hand with a riffler, file or emery paper. Power was applied in the 20th century: tiny grinding wheels for smoothing rotate by long flexible spindle cords connected to electric motors.
  What has changed most, however, is how the die is held. From a crude vise has
  evolved the engravers’ ball, essentially a vise mounted in a large steel ball. The die block is locked in the vise and the engraver's every move is countered with the movement of the vise. It will move in any direction with the slightest pressure of the engraver.
  Cutting a curve, for example, in a die mounted in an engravers' ball is a smooth action of the engravers hand. He points the direction he wants to cut and bears down for the amount of metal he wants to remove. The engravers' ball rotates because it's round bottom moves on a donut-shaped leather pad to facilitate this smooth movement.
  The engraver can cut a die intaglio, cutting the design in negative. Or he can cut cameo, with the positive image constantly in front of him. An intaglio die can be proved, examined in the positive by pressing it in soft material, clay, wax, or soft metal, lead or tin.
  Mostly the engraver works under magnification. He uses permanently mounted
  magnifying lens or eye pieces that enlarge the image he is working on. A loupe is a single eyepiece of more than one lens that is cupshaped and is held next to the eye. Optical visors are worn, much like eye glasses, and give both eyes a view, but one usually has a supplemental lens that magnifies the image even more so. Modern optics has also developed the illuminated magnifier and the illuminated bench lamp for light and magnification.
  Diemaking by reduction punches.  From the time of the first die-engraving pantograph, Hulot's in 1766, the part of the design reduced was only the device, not the lettering. Coin and medalmakers would model the device oversize and this would be placed in the reducing machine. What would be cut is a die (actually a hub) of exact size but only that main portion of the design. This was called the reduction punch.
  The oversize pattern would be positive; the reduction punch made from this pattern also would be positive. This would be hardened and sunk into a die (by hubbing). It would make the device negative in the die. On this same die could be placed the lettering by punches and puncheons (also negative). This could be used as the die for striking; or it could be a patrix (or master die) from which a matrix could be made (again by hubbing) and working dies. Any quantity of working dies could be made from the matrix.
  Literally, this is how the most progressive diemakers created coin and medal dies from 1766 until 1899. It required technologies from several fields:  (1) modeling oversize (from sculpture), (2) making a hard pattern (by casting or electroforming), (3) operation of the die-engraving pantograph (knowledge of mechanics), (4) hubbing (pressing a design in hard metal into soft metal), and (5) heat treating (hardening and softening metal as needed).
  Reducing entire design into the die all at once.  One event by one Frenchman changed diemaking dramatically. Victor Janvier patented, in 1899, his revolutionary
  die-engraving pantograph. His twin cone mechanics made a reducing machine of such fidelity that the entire design – lettering and all – could be reduced at one reduction. Lettering did not need to be added afterwards by punches.
  Coin and medal diemaking passed from engravers, in effect, to sculptors, as the model now was the genesis for any design. The sculptor would create the entire design in bas-relief (working in clay, plasteline or plaster). The lettering would be modeled along with devices, portraits, vignette scenes, subsidiary devices, border elements – everything that was to appear on the surface of the struck piece!
  The design could be viewed on a plaster model in total, before it was placed in production. If corrections needed to be made it was easier to change the model than
  re-engrave a die! The same design could be reduced to several sizes (both mints and medalmakers found this a decided advantage). By viewing the model oversize, mint officials could exert more control over new designs.
  Also the modern die-engraving pantograph could do some amazing things in cutting a die. It could alter the height of the relief slightly (up or down). It could create a camber in the die (for placing a design in a basin shape to fit beneath the rim to reduce coin wear). It could also "flop" a design (from right facing to left facing). As remarkable as the die-engraving pantograph was, there was one thing it could not do: it could not place a bevel on the sides of all relief and lettering – this had to be in the model!
  Thus Victor Janvier changed diemaking for the 20th century. Virtually every mint and medalmaker in the world beat a path to his tiny factory in Paris to obtain his remarkable die-engraving pantographs. He had made possible Matthew Boulton's dream a century earlier, of cutting the entire die in one step.  See pantograph.
  Tracer-controlled diemaking.  At the end of the 19th century, concurrent with Janvier's developing his three-dimensional reducing machine, another kind of reducing machine was being built. The tracer-controlled reducing machine could reduce a design and mill an outline on a small size object, like a die (otherwise the bulk of its work is flat engraving, as for signs).
  A tracer-controlled pantograph cuts a two-dimensional design in a die that can then be roughed out by hand (controlling the milling). What is left is a biplaner design of the outline of relief. This can then be engraved by hand (or power grinder) to create the modulated relief. Lettering can be easily cut in a tracer-controlled die. The major American producer of these machines is Gorton.
  Stronger Dies for Stronger Presses
  Improvement in press design affect the dies. The first screw press was operated by two to eight men. As water power was introduced to minting, replacing man or horse power, greater pressure could be applied to the thrust of the die. The use of steam power with Boulton and Watt's steam engines doubled the pressure even more than what could be applied with a die in a press.
  Stronger presses required stronger dies. Concurrent with press improvement came an improvement in steel technology.  Iron and steel was improved in England by Benjamin Huntsman (1704-1776) who invented a method of making crucible steel. He supplied this better grade of steel to Matthew Boulton and Huntsman's firm specialized is providing steel for diemaking to mints and medal makers for nearly 200 years.
  Those mints and medalmakers who could not procure higher grade steel, such as Huntsman's, had to obtain die forged die blanks from die forgers. These metalworkers were like blacksmiths or swordmakers, who heated and hammered steel until the temper was great enough to sustain striking long production runs of coins or medals. They had to have knowledge of heat treating in addition to iron technology.
  Tool steel and die design not only led to the lengthening of die life and the
  ability to strike thousands of identical coins or medals from a single pair of dies but also the ability of the dies to withstand greater stress, sinking, and the heat generated by the friction of striking. Today dies are made of the finest tool steel for good reason: they must be able to strike several hundred thousand pieces before replacement.
  Coining Dies and Collars
  Several inventions were necessary for modern coining: the invention of the collar and a means of ejecting a piece after it has been struck. An Italian, Francesco Comelli in 1786, was first to do this. All the activities of Boulton and Watt in their Soho Mint at about the same time, improved on this technology: their steam engine for power, their rimming machine for making identical blanks, their presses for striking.
  Along with the use of the finest tool steel, dies now had to be turned on a lathe giving them a long neck to be able to fit within the collar that shapes the edge. Mints now required a tool and die department staffed with craftsmen who could work the steel to create this tooling and shape the dies.
  Press design was altered slightly to accommodate this tooling, as was the making of dies changed to accommodate the tooling. After cutting the design in the end of the die block (by any method), the die was shaped with a long neck and shoulder so the die would enter the collar and retract. The tolerance between the diameter of this neck and the aperture in the collar had to be close – thousands of an inch – or excessive flash or wire edge would form on the struck piece between the two.
  Dies Produced By Hubbing
  In most mints today the tool and die department is concerned with die production, keeping enough dies ahead of the needs of the coining department. Dies are produced in quantity by hubbing. Working dies are made from a master die, which can be used over and over to hub working dies. While the screw press was used for hubbing until 1890, the introduction of electricity, and electric motors, permitted the creation of presses used exclusively for hubbing.
  The 20th century has seen an advance in the development of the hubbing press, perhaps, more than any other coining equipment. Modern hubbing presses can control pressure, dwell time, initial impact, pressing speed, thickness and depth penetration. Working dies can be made in minutes what used to take weeks for hand engravers. The features of a hubbed die include its greater strength and its ability to withstand sinking more so than a machined or handcut die.
  Open Faced Dies
  Once collars were commonplace in mints, everything was struck within a collar including medals. As demand for larger medals increased, larger collars were made. The U.S. Mint in Philadelphia struck medals up to 4 1/4-inch (105mm) diameter with collars to accommodate this size. Medalmakers found this unwieldy and cumbersome. They simply disregarded the collars and struck medals without them.
  The dies, then, did not need a long neck turned on a lathe to shape them to fit within a collar. Dies were left with the design in the center of the face of the die. Dies could be larger with greater mass to strike larger and larger medals. Medals could be struck on other kinds of presses – not just coining presses – but knuckle-joint and hydraulic presses with far greater ease. Medals could be multiple struck to create high relief designs and sizes impossible to produce with coining presses.
  Open face dies gave greater freedom in creating medallic items. Their only
  shortcoming, notwithstanding, was the excessive flash formed on the edge of struck pieces between the dies (this could easily be turned off on a lathe, if round, or trimmed with trimming dies on a press after struck, however). Because they are customarily needed only for short runs, open face dies are cut on a die-engraving pantograph, and these are used without hubbing.
  Die Maintenance
  During the entire life of a die, not only is knowledge of steel required, but a dedication to protect the die from its greatest enemy – rust. Moisture is a killer of dies. They must be kept in an environment of controlled humidity. die vaults must be moisture free. The only other damage to a die is dropping it, or dropping something on its face. Dies are carefully moved from station to station in tote boxes.
  For storage it is also necessary to store a die with some protection. The easiest is to place a struck piece between obverse and reverse dies, one on top of the other
  (or on each die if stored side-by-side). Otherwise a cap can be placed on each, or they can be coated with Cosmolene or petroleum jelly. This is done to prohibit air and moisture from contact with its striking surfaces.
  Die's Afterlife
  Since dies are made of iron and steel they are obviously permanent. Dies used in long production runs are consumed, they are worn out and discarded. Discarded dies are usually cancelled by grinding or surface defacement then sold for scrap iron.
  However, dies for short runs, like a medal issue are still serviceable after the
  required number of pieces are struck. What is to be done with dies after this?  They are put in storage, placed in the die vault. The Paris Mint has stored some dies since the sixteenth century. Despite wars, fires and other ravages, other European mints have stored dies equally as long.
  In America, Medallic Art Company stored both dies and the metal galvano
  dieshells. (Instead of metal galvanos, some modern diemakers use epoxy patterns but these are not suitable for long-term storage.) Thus if called for, the firm could restrike or reissue a medal, particularly for an ongoing award program. (If the die was not serviceable or broke, new dies could easily be made from the existing dieshell – the cheape st form of die insurance, for the cost of storage!) Sometimes retooling was occasionally necessary to bring a die up-to-date by perhaps changing a date or name.
  When medal companies go out of existence, their dies often go to former competitors, other medal companies who buy the assets of the old company. Bastian Brothers of Rochester acquired the dies of Whitehead & Hoag in 1961, for example. Medallic Art Company acquired the dies of August Frank in September 1972. Their dies, in turn, were acquired by Tri State Minting in 1989, which changed its name to Medallic
  Art Company Ltd.
  Infrequently medal clients wish to place their dies in some chosen archives. The
  dies are cancelled, perhaps a specimen or two are struck from these cancelled dies to prove this status; then sent to the archives. State archives have some dies of medals issued in their state, others of national interest have gone to the Smithsonian Institution.
  Rarely a die or two will end up in collectors' hands. Perhaps this is ideal for the
  collector to own and study dies, giving him insight in how his collected pieces are struck.
  In 2017 the dies of Heraldic Art were dispersed to collectors. These dies were all made by Robert MacNamara in his private mint and were offered for sale after sets of 67 medals were struck with CANCELLED DIES.
  References:                                                                                                                              
  C16 {1907} Woodworth, Punches, Dies and Tools for Manufacturing in Presses.
  C20 {1954} Singer, Coin dies and die-cutting, 2:485-492.
  C24 {1965} Breen, Dies and Coinage.
  C29 {1966} Gilbert, Coining dies, #36, pp 24-25.
  C36 {1970} Breen, The Mint Process, How coins are made and mismade.

  excerpted with permission from

  An Encyclopedia of Coin and Medal Technology

  For Artists, Makers, Collectors and Curators

  COMPILED AND WRITTEN BY D. WAYNE JOHNSON

  Roger W. Burdette, Editor

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