An electrode is a tool used in arc welding to produce electric arc. It may be used as a positively charged anode or as a negatively charged cathode.
Arc welding Electrodes of various forms and sizes are used in practice. The most common forms are wire electrode and rod electrode.
Types of Arc Welding Electrodes:
Based on their characteristics, arc welding electrodes can be broadly classified into two types. They are:
- Consumable electrode
- Non-consumable Electrode
If the melting point of an arc welding electrode is less, it melts and fills the gap in the workpiece. Such an electrode is called consumable electrode.
In arc welding, to produce deep weld, consumable electrode is connected to the positive terminal of the power supply (i.e., it is made as anode) while workpiece is connected to the negative terminal of the power supply (i.e., it is made cathode).
This is because, heat concentration is always higher in the anode than in cathode. When consumable electrode is made as anode, it melts faster and easily fills the gap in the workpiece.
Consumable electrodes are usually coated with a flux material. This is done to protect the arc and the weld from the external atmosphere.
Metal inert gas welding is an arc welding technique that uses a consumable electrode.
If the melting point of the arc welding electrode is high, it does not melt to fill the gap in the workpiece. Such an electrode is called non-consumable electrode.
If a non-consumable electrode is used, either the workpiece should have a low melting point or a filler metal with low melting point should be used, to fill the gap in the workpiece.
As non-consumable electrodes do not melt, heat concentration should be high in the workpiece. Hence, in non-consumable electrode processes, to produce deep weld, the electrode is made cathode and workpiece is made anode.
Tungsten is a non-consumable electrode whose melting point is 3422 °C. It is used in tungsten inert gas welding.