Plasma cutting method using double-flow gas

摘要

The metal cutting procedure, using a plasma arc torch (23) with a double gas flow and an electrode (24) with an emissive insert (25), the gas flow being delivered as central and annular peripheral flows, has the central gas flow made up of a mixture of hydrogen and nitrogen and the peripheral flow containing preferably 80 - 100 per cent carbon dioxide. The central flow consists of between 1.5 and 60 per cent, and preferably 4 to 10 per cent, hydrogen and the remainder nitrogen. The insert is made from tungsten or an alloy that is mainly of tungsten, and the electrode is made from copper or an alloy of copper with tellurium or chrome and zirconium.