The technique of electric arc welding It consists of the fusion of a metal at a high temperature by using a potential differential and intensity value of a determined electric current. By means of this potential difference, the air is ionized and the electrons are transported through the electrodes and the piece to Weld. The heat generated (4000°C), melts both the base material and the filler material, which is deposited and creates the so-called Weld. The electrodes are also known as filler material” they are covered with a non-metallic substance whose chemical composition is very varied (Cellulose, Titanium Oxide, Calcium Carbonate and Calcium Fluoride). Others types of electric arc welding are:
- Arc welding with covered electrode
- Gas Shielded Arc Welding
- Arc welding with flux powder or submerged arc
Arc Welding Process
1.- General Start Conditions:
1.1. Both the electrodes as well as the surfaces to be welded must be free of all types of contamination, as well as grease, dust, humidity, and surface defects.
1.2. Knowing the current/voltage relationship we can choose the characteristics of the arc. Generally, a voltage between 40 and 110 V is needed; this voltage drops to maintenance values between 15 and 35 V.
2.- Materials and Equipment
2.1. Welding machine (Power Source), most shops use welding machines with voltage outlets at 220 V or 380 V with ground line. The change of polarity is carried out only if the machine is turned off.
2.2. welding circuit, When the electrode holder is not in use, it must never be left on the table or in contact with any other object that has a direct line to the surface where it is being welded. The danger in this case is that the electrode holder, in contact with the ground circuit, causes a short circuit in the transformer of the equipment. Welding is not a risky operation if proper preventive measures are followed. This requires an awareness of the potential for injury that can occur in welding operations and regular safety precautions by the operator.
3.- Arc Welding Procedure
While keeping the electrode an electric spark is produced on the joint while the base and the electrode, forming the Weld, the appearance of a bright point indicates that the metal has reached its melting point when this state is maintained a welding bright and regular, without excess thickness and without the formation of “Dross”.
Arc Welding Applications
They are appropriate for vertical welding, have high penetration in all positions and give reasonable mechanical properties. They generate a large amount of hydrogen with the risk of fractures in the zone affected by heat. The arc welding It has certain advantages over other methods. It is faster due to the high concentration of heat that is generated and therefore produces less distortion in the joint. In some cases they are used fusible electrodes, which are the filler metals, in the form of flux-coated or bare rods; In other cases, use a refractory electrode of tungsten and the filler metal is added separately.
Video Arc Welding
Know Other types of Welding