Coining is a form of precision
stamping in which a workpiece is subjected to a sufficiently high
stress to induce
plastic flow
In physics and materials science, plasticity (also known as plastic deformation) is the ability of a solid material to undergo permanent deformation, a non-reversible change of shape in response to applied forces. For example, a solid piece of ...
on the surface of the material. A beneficial feature is that in some metals, the
plastic
Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...
flow reduces surface
grain
A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and ...
size, and
work hardens the surface, while the material deeper in the part retains its
toughness
In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing.[ductility
Ductility refers to the ability of a material to sustain significant plastic Deformation (engineering), deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic def ...]
. The term comes from the initial use of the process:
manufacturing of coins.
Coining is used to manufacture parts for all industries and is commonly used when high relief or very fine features are required. For example, it is used to produce
coins
A coin is a small object, usually round and flat, used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order to facilitate trade. They are most often issued by ...
,
badge
A badge is a device or accessory, often containing the insignia of an organization, which is presented or displayed to indicate some feat of service, a special accomplishment, a symbol of authority granted by taking an oath (e.g., police and fir ...
s,
buttons, precision-energy
springs and precision parts with small or polished surface features.
Coining is a
cold working process similar in other respects to
forging
Forging is a manufacturing process involving the shaping of metal using localized compression (physics), compressive forces. The blows are delivered with a hammer (often a power hammer) or a die (manufacturing), die. Forging is often classif ...
, which takes place at elevated temperature; it uses a great deal of force to elastically deform a workpiece, so that it conforms to a
die. Coining can be done using a gear driven press, a mechanical press, or more commonly, a hydraulically actuated press. Coining typically requires higher tonnage presses than stamping, because the workpiece is elastically deformed and not actually cut, as in some other forms of
stamping. The coining process is preferred when there is a high tonnage.
Coining for currency
Coining in electronic industry
In
soldering
Soldering (; ) is a process of joining two metal surfaces together using a filler metal called solder. The soldering process involves heating the surfaces to be joined and melting the solder, which is then allowed to cool and solidify, creatin ...
of
electronic component
An electronic component is any basic discrete electronic device or physical entity part of an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singula ...
s, bumps are formed on
bonding pads to enhance
adhesion
Adhesion is the tendency of dissimilar particles or interface (matter), surfaces to cling to one another. (Cohesion (chemistry), Cohesion refers to the tendency of similar or identical particles and surfaces to cling to one another.)
The ...
, which are further flattened by the coining process. Unlike typical coining applications, in this case the goal of coining is to create a flat, rather than patterned, surface.
"US Patent 5132772 - Semiconductor device having tape automated bonding (TAB) leads which facilitate lead bonding"
, section "Background of the invention", which gives an overview of common techniques
References
Metal forming
Production of coins
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