The factors affecting the stability of the welding arc mainly include the following aspects
(1) Welder operation technology and automatic welding arc length automatic adjustment ability
Welder's operation technique is an important factor to determine the arc stability. During the actual welding process, the welder's gun (bar) gesture should be appropriate, and the arc length should be kept unchanged as much as possible, otherwise the welding current will fluctuate or even the arc will be broken. The angle between the wire and the workpiece, and the torch and the workpiece, should be appropriate to produce proper penetration, prevent weld defects, and maintain the weld pool. For automatic welding, it is required that the arc length can be automatically adjusted to ensure that the arc length remains constant during the welding process, thereby ensuring the constant welding parameters.
(2) Arc welding power source
①Types of arc welding power sources DC arc welding power sources and square wave AC arc welding power sources have better arc stability than sine wave AC arc welding power sources. The stability of pulse arc welding power source is better, therefore, pulse arc welding power source is usually used in small current welding.
②External characteristics of arc welding power source The external characteristics of the power source should meet the requirements of the arc stable combustion of the corresponding welding method. The MIG welding generally uses thin wires (the diameter of the welding wire is not more than 3.2mm). Thick wire is sometimes used for arc unstable and high current MIG/MAG welding, but when thick wire is used, a power supply with steep drop characteristics should be selected.
③ The dynamic characteristics of the power supply The short-circuit transition CO2 welding arc burns and extinguishes periodically. It is required that the no-load voltage of the power supply rises quickly and the short-circuit current rises at a moderate speed.
④ No-load voltage of arc welding power source The higher the no-load voltage of the arc welding power source, the easier the arc strike, and the better the stability of the arc combustion; but when the no-load voltage is too high, it is not good for the personal safety of the welder.
(3) Welding current
The larger the welding current, the higher the temperature of the arc, the stronger the gas ionization degree and the heat emission effect in the arc column area, and the more stable the arc combustion.
(4) Arc voltage
The arc voltage should be properly matched with the welding current, and the arc voltage should increase as the welding current increases. When the welding current is constant, if the arc voltage is too small, it is easy to cause a short circuit; if the arc voltage is too large, the arc will swing violently, which will destroy the stability of the welding arc.
(5) Workpiece surface condition, airflow and magnetic deflection
The surface of the workpiece is not clean, such as oil stains, rust, moisture, etc., the arc ignition and arc ignition are unstable, and when the protective airflow is unstable or there is magnetic bias blowing, the arc is also unstable.
