Coining is a form of precision
stamping in which a workpiece is subjected to a sufficiently high
stress
Stress may refer to:
Science and medicine
* Stress (biology), an organism's response to a stressor such as an environmental condition
* Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...
to induce
plastic flow on the surface of the material. A beneficial feature is that in some metals, the
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
flow reduces surface
grain 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 is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile str ...]
. 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, flat (usually depending on the country or value), round piece of metal or plastic 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 t ...
,
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 ...
s,
buttons
A button is a fastener that joins two pieces of fabric together by slipping through a loop or by sliding through a buttonhole.
In modern clothing and fashion design, buttons are commonly made of plastic but also may be made of metal, wood ...
, precision-energy
springs and precision parts with small or polished surface features.
Coining is a
cold working
In metallurgy, cold forming or cold working is any metalworking process in which metal is shaped below its recrystallization temperature, usually at the ambient temperature. Such processes are contrasted with hot working techniques like hot r ...
process similar in other respects to
forging, which takes place at elevated temperature; it uses a great deal of force to plastically 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 plastically 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 in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involv ...
of
electronic components, bumps are formed on
bonding pad
Contact pads or bond pads are designated surface areas of a printed circuit board (PCB) or die of an integrated circuit.
Possibilities to contact to pads include soldering, wirebonding, flip chip
Flip chip, also known as controlled collapse ...
s to enhance
adhesion
Adhesion is the tendency of dissimilar particles or surfaces to cling to one another ( cohesion refers to the tendency of similar or identical particles/surfaces to cling to one another).
The forces that cause adhesion and cohesion can b ...
, 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
{{design-stub