Manual arc welding is called so because all the required actions are carried out manually by a specialist welder. His responsibilities include starting and maintaining the arc, moving the arc contact over the required gap, and supplying new electrodes to replace the used ones. The quality of the welded joint directly depends on the qualifications of the welder. It is necessary to quickly strike the arc, carefully ensure that its length is unchanged, and also weld the two parts evenly.
Manual welding has a certain classification. For example, according to the number of electrodes used, welding with one or two electrodes is distinguished, as well as multi-electrode welding. There are three-phase and single-phase arcs, while the nature of the current can be variable or constant.
At present, welding on alternating or direct current using consumable electrodes has become widespread. Of course, there are many different ways to connect a part using welding. For example, with the formation of different types of seams (with flanging). To increase labor productivity, it is recommended to use a beam of electrodes, and when welding various alloys and non-ferrous metals, tungsten electrodes are used.electrodes.
Manual welding has a specific technological process. When welding parts, a variety of electrodes are used, which can be consumable and non-consumable. The former can be made from welding wire with a special coating. Such sputtering is necessary for a high degree of stability of the electric arc, providing slags and oxides on the metal surface that protect the weld pool from interaction with the environment, as well as to protect the arc area from interaction with air.
Manual welding can be carried out under various environmental conditions and in various gases. For example, manual argon arc welding (argon), air welding, etc.
According to GOST 9466-75, electrodes are divided into several types.
1. By appointment:
- low alloy structural and carbon steels;
- alloy steels;
- alloy heat resistant steels;
- high alloy structural steels.
2. By type and brand:
- standard;
- non-standard.
3. According to the thickness of the sprayed coating:
- thin;
- average;
- thick;
- very thick.
4. By type of electrode coating:
- acid;
- rutile;
- cellulose;
- iron powder coating.
5. According to the allowable spatial position of the electrodes:
- for any positions;
- for any other than vertical manual welding;
- for bottom and horizontal on a vertical plane;
- for the lower "in the boat".
6. According to the polarity of the welding current used:
- straight;
- reverse;
- any.
7. By type of welding current:
- permanent;
- variable.
Manual welding assumes that the metal that is deposited with electrodes must have a chemical composition that meets the requirements for it. The mechanical characteristics of the resulting weld and the metal deposited on it must be brought into line with the standards of GOST 9467-75.
