Stolen from: http://groups.yahoo.com/group/castinghobby/files/Foundry%20Gases/Oxyfuel%20cutting.doc Oxyfuel cutting - process and fuel gases
Mechanized oxyacetylene cutting system The oxy-fuel process is the most widely applied industrial thermal cutting process because it can cut thicknesses from 0.5mm to 2,500mm, the equipment is low cost and can be used manually or mechanized There are several fuel gas and nozzle design options that can significantly enhance performance in terms of cut quality and cutting speed.
Process fundamentals
The cutting process is illustrated in Fig. 1. Basically, a mixture of oxygen and the fuel gas is used to preheat the metal to its 'ignition' temperature which, for steel, is
700°C - 900°C (bright red heat) but well below its melting point. A jet of pure oxygen is then directed into the preheated area instigating a vigorous exothermic chemical reaction between the oxygen and the metal to form iron oxide or slag. The oxygen jet blows away the slag enabling the jet to pierce through the material and continue to cut through the material.
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Oxy-fuel cutting
Stolen from: http://groups.yahoo.com/group/castinghobby/files/Foundry%20Gases/Oxyfuel%20cutting.doc Fig.1. Diagram of oxyacetylene cutting process
There are four basic requirements for oxy-fuel cutting:
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the ignition temperature of the material must be lower than its melting point otherwise the material would melt and flow away before cutting could take place the oxide melting point must be lower than that of the surrounding material so that it can be mechanically blown away by the oxygen jet the oxidation reaction between the oxygen jet and the metal must be sufficient to maintain the ignition temperature a minimum of gaseous reaction products should be produced so as not to dilute the cutting oxygen
As stainless steel, cast iron and non-ferrous metals form refractory oxides; i. e. the
oxide