Carbon Arc Cutting:

Generally this process is used merely when arc or oxyfuel gas cutting is not available. The amperages utilized for carbon arc cutting are usually higher than for welding on the similar metal thickness.

Before beginning the cutting, the carbon electrode must be ground to a very sharp point. The length of the taper must be 6 - 8 times the electrode diameter. The electrode must stick out from the electrode holder a distance equivalent to 10 times the electrode diameter. This is essential to reduce electrical resistance and heating influenced on the electrode. The electrode angle must be about 20 degrees from vertical to cut completely. The carbon arc method of cutting is successful on cast iron since the temperature of the arc is adequate to melt the iron oxides formed.

The cut must be made from top to bottom, or vertically down. It will keep the molten metal passing out of the gauge area. The graphite form of carbon electrodes is preferred because high currents are required.

In this base metal is melted by the heat of the arc. Metal is eliminated from the kerf by the force of the gravity and arc. The quality of the cut is poor generally. This method is utilized in small shops where more capable and costly equipment is generally not available.