Non-ferrous metal cutting
For cutting non-ferrous metals, the use of conventional oxy-fuel cutting technology is impossible due to the absence or insufficient amount of iron in their composition for a full-fledged iron oxidation reaction: Fe + O2. + T = Fe0 + O2 + t = Fe2O3 + O2 + t = Fe3O4.
Therefore, plasma cutting is used to cut aluminum, bronze, brass, copper, and other non-ferrous metals.
The plasma arc is ignited between the cathode (electrode) and the anode, cut with metal as in conventional electric arc welding, and blown out by plasma gas, forming a stream of ionized gas – high-temperature plasma. The energy of the plasma arc reaches tens of thousands of degrees, applied to the heating spot at the cut, as a result of which any material instantly melts or even evaporates, and is blown out by the excess pressure of the plasma-forming gas jet. Due to this high temperature, it is possible to cut any conductive material, which includes all non-ferrous metals.
When it comes to cutting large-sized parts or slabs of aluminum, copper or brass, or thick bronze castings such as ship propellers, so-called oxy-flux cutting is used. The essence of the method lies in the fact that fine iron powder is fed into the cutting zone, which, reacting with oxygen, raises the temperature of the melt zone to almost 4000K. As a result, the base metal begins to melt and the kinetic energy of oxygen and flux blows it out of the cutting zone.
With this technology, you can cut thick non-ferrous metal up to 800 mm thick or more. If the task is to cut very thick castings, oxygen-flux cutting with an oxygen lance is used.
The essence of this method is that oxygen and iron powder are fed into an iron tube with a diameter of usually 3/8 or 1/2 inches, which increases the amount of iron required for the combustion reaction of iron in oxygen, and the temperature in the melt zone rises to 4000K, which melts the base metal, which is blown out of the tube by excess pressure of oxygen.