The micro arc coil termination process
The micro arc coil termination process requires a number of turns of wire to be wound onto the pin in a uniform fashion and density. Best winding practice is best determined through trials. However, as a general rule, two or three turns uppermost with two or three turns lowermost is usually best.
The wound pin is positioned close to a welding electrode (typically 2 or 3 mm) and an arc struck between the pin and the electrode.
By profiling the energy and current within the arc in terms of rate of rise, period of peak and downward cooling, the rate at which the pin begins to melt back may be controlled.
The process of melting the pin back creates a molten ball simultaneously, causing the wire and its insulation to melt and thus welding the wire to the pin.
In order to control such a process in terms of energy control, sophisticated closed-loop power supplies are employed to establish and then maintain the arc under precisely controlled electrical conditions.
By modifying the programmed conditions, the effective heating pattern and welding process can be established and controlled.