Carbon cutting or air carbon arc cutting uses an electric arc to melt metal. It blows away the melted or molten metal through the use of compressed air that is sent out in a high velocity jet. Instead of being a chemical reaction as in many processes it is a physical one and can be used with most metals.
Generally this type of cutting is used by industries like mines, construction and quarries to remove stainless welds or hard surfaces. They also use this method when they are preparing cast iron or manganese steel for repairs. Other uses for this method are to cut steel plates that may have been embedded into concrete or to cut pilings where you do not want to remove back fill.
This method only needs a regular power source for the cutting with sufficient amperage – between 150 -600 amps depending on the electrode size, and Direct Current Reverse Polarity. Cutting can be made on most metals including iron, steel, stainless steel, copper and nickel alloys and iron; it can also be used with aluminum. The air pressure needed is generally provided by any canister of compressed air that is 80-100 psi for air pressure.
In most cases a heavy duty welding machine will do this cutting and has to have a constant current. Some applications of this cutting do use alternating currents and they must use an AC type of carbon electrode.
Carbon arc cutting is used to cut metal but it is also used to gouge out any defects in a metal, it can remove bad welds and it can prepare grooves that are waiting for welding. This cutting produces a small cut so that the metal that surrounds the area that is being worked on does not go to high temperatures because the metal is removed quickly after it is melted. Also, because this process is quick, it reduces the tendency of the metal to crack or become distorted. The process usually is a manual process rather than an automated one.
Carbon Arc Cutting is not recommended if the welder is going to do weld preparation for the following metals: titanium, stainless steel, zirconium or other types of metals that need cleaning before they are cut. They will have to be cleaned thoroughly through grinding so that any carbonized material next to the cut is completely cleaned away. However, when these materials need to be scraped to remelt them, this process can be used.
There are a few safety precautions that must be taken into consideration when dong carbon arc cutting. Metal deflection plates must be put up if the welder is gouging because the air blast that is used can make molten metal travel over several feet.
It is important to also move any materials that are combustible because the molten metal can become a fire hazard since it travels at such a high level. This is also a very loud process so some type of ear protection should be worn by the person cutting the arc.