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Arc Welding: Cathode Spot and Anode Spot and Their Characteristics
Arc welding is a welding process wherein coalescence of metals is produced by heating them with an arc between the work pieces and a consumable electrode. This process enables the manufacture of welds easier, faster, and cheaper. One of the main advantages of using arc welding is the high deposition rates achieved by this process.
One of the aspects of arc welding is the ‘spot welding’ of metals. It is a type of welding in which two pieces of the same or heterogeneous metal sheets or plates are placed one above the other and then joined to each other by a single welding arc. The spot welding process is commonly used in the automotive industry due to its effectiveness and also its cost-saving potential.
When arc welding, the electrodes used in the process are either of two types; cathode or anode.
For the cathode spot welding process, the cathode is made up of an insulated copper wire, which is covered with a graphite coating. It is then placed against the material to be welded and electrically connected to a direct current welding machine. The welding current then passes through the electrode, melting the material and creating a welded joint. The cathode is a negative electrode and the material is the anode material.
The advantage of this type of welding is that it produces a weld stronger than that of a conventional weld by instigating a stronger bond between the two pieces due to the higher surface area. However, this type of welding requires that the electrodes should be in contact with the materials at all times and it may require a certain level of skill and expertise in order to achieve the desired results.
The anode spot welding process is the opposite of the cathode process. The anode is made up of an insulated copper wire, just like in the cathode process, but with a tungsten coating instead of a carbon coating. The anode is connected to a ‘positive’ direct current welding machine. The welding current then passes through the electrode and creates a welded joint with a high strength.
The advantages of the anode spot welding are that it produces a stronger weld, it is faster than the cathode process, and the welding machine does not require any contact between the electrodes and the workpiece, therefore reducing the amount of time necessary to create the weld. In addition, it minimizes the risk of ruining the workpiece due to an excessive heat from the welding process.
To conclude, arc welding can be used for both cathode and anode spot welding processes, each having different advantages and disadvantages depending on the particular application. The type of welding chosen should be dependent on the desired results and the capabilities of the operator. With the right arc welding techniques and the correct equipment, spot welding can be successfully used to join materials that can greatly benefit a certain process or form of fabrication.
