Manual electric arc welding is called so because a specialist welder carries out all the required actions manually. His responsibilities include igniting and maintaining the arc, moving the arc contact over the required interval, the receipt of new electrodes to replace the used ones. The quality of the welded joint depends on the qualifications of the welder. It is necessary to quickly ignite the arc, carefully monitor that its length is unchanged, and also to make uniform welding of two parts.
Manual welding has a certain classification. For example, the number of electrodes used distinguishes welding with one or two electrodes, as well as multi-electrode. There are three-phase and single-phase arcs, while the nature of the current can be alternating or constant.
Currently, AC or DC welding using melting electrodes is widespread. Of course, there are many different ways to weld a part. For example, with the formation of different types of seams (with flanging edges). To increase labor productivity, the use of a beam of electrodes is recommended, and when welding various alloys and non-ferrous metals, tungsten electrodes are used .
Manual welding has a specific process. When welding parts, a variety of electrodes are used, which can be melting and non-melting. The former can be made of welding wire with a special coating. Such spraying is necessary for a high degree of stability of the electric arc, to ensure on the metal surface slags and oxides that protect the weld pool from interaction with the environment, and also to protect the arc region from interaction with air.
Manual welding can be carried out under various environmental conditions and in various gases. For example, manual argon - arc welding (in argon medium ), welding in air, etc.
According to GOST 9466-75, electrodes are divided into several types.
1. By appointment:
- low alloy structural and carbon steels;
- alloy steels;
- alloyed heat-resistant steels;
- high alloy structural steels.
2. By type and brand:
3. The thickness of the spray coating:
- thin;
- average;
- thick;
- especially thick.
4. By type of electrode coating:
- acidic;
- rutile;
- cellulose;
- iron powder coating.
5. According to the permissible spatial position of the electrodes:
- for any provisions;
- for any, except vertical manual welding;
- for lower and horizontal on a vertical plane;
- for the bottom "into the boat."
6. By the polarity of the welding current used:
7. By the nature of the welding current:
Manual welding suggests that the metal, which is fused with electrodes, must have a chemical composition that meets the requirements for it. The mechanical characteristics of the resulting weld and metal deposited on it should be brought into compliance with the standards of GOST 9467-75.