Annealing by short circuit is a method of efficiently annealing copper wire which employs a controlled electrical

short circuit A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit ...

. It can be advantageous because it does not require a

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on ...

-regulated furnace like other methods of annealing.

Process

The process consists of two conductive pulleys (''step pulleys'') which the wire passes across after it is drawn. The two pulleys have an electrical potential across them, which causes the wire to form a short circuit. The Joule effect causes the temperature of the wire to rise to approximately 400 °C. This temperature is affected by the rotational speed of the pulleys, the ambient temperature, and the voltage applied. Where

t

is the temperature of the wire,

K

is a constant,

V

is the

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge t ...

applied,

r

is the number of rotations of the pulleys per minute, and

t_a

is the ambient temperature: :

t = \frac + t_a

The constant

K

depends on the diameter of the pulleys and the

resistivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...

of the copper. Purely in terms of the temperature of the copper wire, an increase in the speed with which the wire passes through the pulley system has the same effect as a decrease in resistance. Therefore, the speed with which the wire can be drawn through varies quadratically as the voltage applied.

References

* Thesis of Degree, Cable Manufacture and Tests of General Use and Energy. - Jorge Luis Pedraz (1994), UNI, Files, Peru. * Dynamic annealing of the Copper wire by using a Controlled Short circuit. = Jorge Luis Pedraz (1999), Peru: Lima, CONIMERA 1999, INTERCON 99, {{DEFAULTSORT:Annealing By Short Circuit Metal heat treatments

Process

See also

References