What is Carbon Arc Welding?
Carbon arc welding (CAW) is a process that produces the coalescence of metals by heating them with an arc between a non-consumable carbon (graphite) electrode and the workpiece. In carbon-arc welding, a carbon electrode is used to produce an electric arc between the electrode and the materials being bonded.
It was the first arc-welding process developed but is not used for many applications today, having been replaced by twin-carbon-arc welding and other variations. The purpose of arc welding is to form a bond between separate metals. This arc produces temperatures in excess of 3,000 °C. At this temperature, the separate metals form a bond and become welded together.
Related: What is Arc Welding?
The History Behind
Carbon arc welding is impossible without an electric arc. In 1800, Sir Humphry Davy discovered the electric arc. Later, Nikolay Benardos and Stanislaw Olszewski discovered the CAW process in 1981. Initially, this welding process was given the name Elektrogefest.
Equipment
- Electrode: The diameter of the electrode used in this process is around 3 to 22 mm.
- Power source: In the CAW process, direct current welding machines are used as a power source. These machines can be either of the rotating or rectifier types.
- Electrode holder: You may have a question; do we use the same conventional electrode holder in the CAW? No. As the temperature involved in this process is very much high, we can’t use the traditional electrode holder during this process.
Working Of Carbon Arc Welding
An electric arc is generated between the electrode and the parent metal. The heat generated due to the electric arc melts the base metal. After the solidification of the molten metal, the required weld is produced in the given region. You can vary the size of the electrode used in the process depending on the generated current.
One of the variations of the CAW is twin carbon arc welding (TCAW). TCAW is a slightly different process than CAW.
In the TCAW, a special type of electrode is used. TCAW is designed in such a way that one carbon electrode is movable and can be touch with the other to produce the arc.
During the twin carbon arc welding alternating current is used. Also, electrodes should be burned off at equal rates in the TCAW.
Advantages of Carbon Arc Welding
- The heat developed during the welding can be easily controlled by adjusting the length of the arc.
- It is quite clean, simple, and less expensive when compared to other welding processes.
- Carbon arc welding is faster than other welding processes, making it ideal for large projects.
- Carbon arc welding produces less slag than other welding processes, making it easier to produce a clean weld.
- Carbon arc welding is less likely to cause warping and distortion than other welding processes.
- Both the ferrous and non-ferrous metals can be welded.
- The carbon arc welding process can be done automatically using electronic controllers.
- For soldering, brazing and braze welding, etc., carbon arc welding is the best method of heat source.
Disadvantages of Carbon Arc Welding
- In the case of ferrous metal, there is a chance of disintegrating the carbon at high temperature and transferring to the weld, which causes weld deposit to be harder and brittle.
- In the absence of proper electrode geometry, arc blow results which give poor welds with blow holes.
- A separate filler rod must be used if any filler metal is required.
- The current required to attain welding temperature is almost double the current required in metal arc welding.
- Carbon arc welding can be efficiently and economically done with dc supply.