Dick Johnson submitted this entry from his Encyclopedia of Coin and Medal Terminology. Thanks. -Editor
Displacement. The result of metal movement within a struck blank caused by the configuration of the die and the metal mass
seeking to fill the nearest cavities of the die. The movement of the mass is called metal flow, displacement is the result of this plastic flow of solid
material. There is some displacement throughout the blank (if it is one homogeneous mass, not clad) but it is obvious to observe as surface displacement, which
forms the design, the modulated relief of the contours and cavities of the die.
Metal tends to flow towards the greatest die cavity during striking. The force of the blow causes nearby metal to flow into that cavity; it draws adjacent
metal mass to replace the metal which flowed into the cavity. This movement of solid material, metal flow, redistributes the metal throughout the
mass of the blank until all die cavities are filled (although this happens instantly).
The blank's mass is reshaped until it fits exactly the intended configuration of both dies (also expanding slightly to the limits of the collar). The
design is formed, not by surface displacement alone, but metal flow occurs throughout the metal blank.
Obviously, displacement is best observed on the surface. However, we can view the displacement within the struck piece if a coined piece is dissected and
the change of internal grain structure is and the metal flow effect can be observed. Or, it can also observed by a lamination error
where a layer of struck surface metal is severed from a coin. A minute amount of displacement can be observed within the exposed mass.
Interestingly, displacement does not occur beyond the first layer of clad metal. Numismatic writer Walter Breen named the line between two clad layers as
the boundary. This is apt because displacement does not extend beyond the boundary of the first layer in clad coins.
Book lovers should be word lovers as well.
Looking for the meaning of a numismatic word, or the description of a term? Try the Newman Numismatic Portal's Numismatic Dictionary at: https://nnp.wustl.edu/library/dictionary
Or if you would like a printed copy of the complete Encyclopedia, it is available. There are 1,854 terms, on 678 pages, in The Encyclopedia of
Coin and Medal Technology. Even running two a week would require more than 19 years to publish them all. If you would like an advance draft of this vital
reference work it may be obtained from the author for your check of $50 sent postpaid. Dick Johnson, 139 Thompson Drive, Torrington, CT 06790.
Wayne Homren, Editor
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