定義

• Die Life.  The number of pieces struck by a die before it is withdrawn from use. Rather than a measurement of time, die life is expressed in a number of pieces a given die strikes. There is no way of knowing in advance the life of a die; it can break on the first blow or still be serviceable 100 years and a million blows after it was made. The greatest enemies to dies are, of course, wear and rust, but dies also break, become sunken, pitted, damaged, all of which would prohibit their continued use – until they simply cannot strike satisfactory pieces.
  Long die life.  Perhaps there are more older dies, still serviceable, in the Paris
  Mint than anywhere else in the world. One, the original obverse of the first American medal, Washington Before Boston, 1789, has been in constant use, it is said, from 1790 until the early 1900s. (The reverse dies were replaced several times, creating at least three French versions of this medal.) But the original obverse has apparently lasted for more than 210 years! The Paris Mint has some original dies from the 14th century and has struck some of these side-by-side in soft tin for a series of modern restrikes. This is certain evidence of their excellent techniques of die storage and preservation.
  The maximum life of coining dies in modern times range from 300,000 to 500,000 (expressed 400,000"100,000) impressions. For medal dies it is considerably less (about ten percent of this for medal dies); in most cases dies outlast the number of medals required for most medal programs.
  Here is a list of factors that influence the life of a die:
  1)  die wear,
  2)  type of steel,
  3)  degree of hardening,
  4)  impurities in the steel,
  5)  how quickly the die sinks,
  6)  high stress areas in the design,
  7)  hardness of blanks being struck,
  8)  method by which the die is hardened,
  9)  pressure established during each setup, and
  10)  protection afforded the die during storage.

  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

人际关系