Even people who have never picked up a welder in their lifetime likely understand the basic concept behind arc welding.
A heated torch, or welder, creates an electric arc between a metal electrode located on the end of the welder and the piece of metal being worked on. Heat is applied until the end of that metal piece is malleable.
Then, the heated metal is bonded with another piece of metal via the application of pressure. The metal bond is cooled, and voila: where once there were two pieces of metal, now there’s just one.
Carbon arc welding takes this concept a step further by replacing the metal electrode with a carbon electrode. This process has been around for years, and its applications have only increased. Read on while we further explain carbon arc welding.
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It was the first arc-welding process developed but is not used for many applications today, having been replaced by twin-carbon-arc welding and other variations.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 touched 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 advantages of carbon arc welding are given as follows:
- Carbon arc welding is easily adaptable to automation.
- In carbon arc welding, the temperature of the molten pool can be easily controlled by changing the arc length.
- Carbon arc welding can be easily adapted to the inert gas shielding of the weld.
- Carbon arc welding can be used as an excellent heat source for many welding processes such as soldering, brazing, braze welding, etc.
Disadvantages of Carbon Arc Welding
The disadvantages of carbon arc welding are as follows
- Carbon arc welding can only be used on DC supply.
- The carbon electrode requires approximately twice the current to raise the temperature of the work to welding temperature as compared with metal electrode.
- If any filler material is required, then a separate filler rod has to be used in the carbon arc welding.
- In carbon arc welding, blow holes occur due to magnetic arc blow, especially when welding near the edges of the workpiece.
- In carbon arc welding, the arc serves only as a source of heat and it does not transfer any metal to reinforce the weld joint.
Applications of Carbon Arc Welding
Carbon arc welding is commonly used in the following application
- Carbon arc welding is useful for welding thin high-nickel alloys.
- With carbon arc welding, the model metal can be easily welded by using a suitable coated filler rod.
- Carbon arc welding can be used for welding the galvanized sheets using the copper-silicon-manganese alloy filler rod.
- The carbon arc welding can also be used for welding stainless steel of thinner gauges with excellent results.
- The carbon arc welding is adaptable for automation particularly where the amount of weld deposit is large and the materials to be fabricated are of simple geometrical shapes such as water tanks.