Welding electrode is a piece of wire or rod, which can be of metal or alloy and has a flux with or without flux and carries an electric current to obtain sufficient heat for welding. At one end it is fastened to a holder and an arc is installed at the other.
Electrodes are the most part of welding work. Welding without electrodes is impossible in most welding processes, mainly divided into two parts, based on the electrode work function.
Types of welding electrode
Depending on the function, electrodes can be classified as follows:
- Non-Consumable Electrode
- Consumable electrode
- These electrodes do not fuse at the time of welding and only act as electrical conductors that generate arcs to obtain sufficient heat, called none-consumable electrodes, and they are made up of high melting point metals Such as tungsten ( melting point 6150 ° F), carbon (melting point 6700).
These electrodes do not melt while welding and separate filler wire required with these electrodes to fill the joint. However, due to the evaporation and oxidation of the electrode during welding, the length of the electrode decreases with the passage of time.
None consumable electrode may be classified as follows:
a- Carbon or Graphite electrodes
b- Tungsten Electrodes
Non-consumable electrodes often have copper-coated carbon or graphite electrodes. The copper coating increases the electrode’s electrical conductivity or current conduction capacity.
Carbon electrode and graphite electrode
Carbon Electrode is less expensive than graphite electrodes. The resistive capacitance inside the carbon electrode is higher as compared to the graphite electrode, as a result, this current stream takes comparatively less, short life due to soft material while the graphite electrode is more expensive, carrying current more because of less electrical resistance. Its material is hard and brittle thus the carbon electrode has longer life as compared to the carbon electrode.
The next electrode in the series of non-consumable electrodes is tungsten which can be basically classified as follows:
Zirconiated tungsten, (0.3 to0.5%)
Thoriated tungsten (1 -2%).
In pure tungsten the alloy increases, resistance to contamination, arc stability, and electrode life. In addition, arc initiation is easy, the electrode tip remains cold (compared to pure tungsten electrodes), electrode consumption is low and current carrying capacity gains. Compared to carbon electrodes, tungsten electrodes are much more expensive and alloy tungsten electrodes are still more COStlier. Tungsten/alloy tungsten electrodes from 0.5 mm to 6 mm directors are commonly available for welding purposes
Consumable (Metallic)Welding Electrodes
These type of welding electrodes have a low melting point, act as electrical conductors that generate arcs to obtain sufficient heat, melts itself and fills the joint, are called consumable welding electrodes,
Consumable electrodes can be classified as follow:
a- Bare electrode
b- Flux covered electrode
a- Bare Electrodes:
This type of electrodes requires additional shielding to protect the metal from atmospheric contamination of the molten weld pool which may be in the form of gas or flux.
b- Flux covered electrodes
In this type of electrodes, do not require any additional shielding to protect the metal from atmospheric contamination. These are themselves coated with fluxes that would completely cover the weld pool as slag at the time of welding. And are subsequently removed after cooling.