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Oxy-fuel Cutting |
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With just gas, a good torch and a steady hand, and you're ready to cut steel anywhere. No electricity or complicated equipment is needed - just you, the metal and the gas. And that's the way it's been since the beginning of the last century.
Oxy-fuel cutting is a combustion process. An oxygen jet burns the metal in a narrow section to make a cut and removes the combustion products (slag) from the kerf. The purity of the cutting oxygen is of key importance for the cutting speed that can be achieved. High purity oxygen means high productivity. Before oxy-fuel cutting can begin, the steel must be preheated to ignition temperature. This is done by means of an oxygen/fuel gas flame. The choice of fuel gas influences the cutting process with regard to quality, preheating times and the thickness of the material that can be cut with good results. The most critical part of the cutting equipment is the cutting nozzle. The performance of a nozzle rises with the increasing exit velocity of the cutting oxygen jet, which in turn depends on the design of the nozzle orifice. Working with fuel gases and oxygen can be risky if the person using the equipment does not have sufficient knowledge of the equipment and its installation, handling and care.
Oxy-fuel cutting is used for mild and low-alloy steel in a material thickness of up to a few meters! The surface condition has a certain influence on the cut quality, for example different types of shop primers for temporary protection against corrosion. Straight cuts, bevel cutting or weld-edge preparation with several torches simultaneously are just a few options offered by this versatile tool. Another is the potential for easy mechanization. |
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Coating a steel plate with a shop primer for the purpose of temporary protection against corrosion affects the flame cutting properties of the plate. Both the type of shop primer and the thickness of the primer film have a strong impact on the loss-of-cut speed, the highest achievable cutting speed without cutting defects, and the formation of adhesive slag.
Among 22 different types of shop primers, four groups can be specified:
- Iron oxide primers with PVB/phenolic resin
- Iron oxide primers with epoxy
- Zinc primers with epoxy
- Zinc primers with alkyl silicate
The cutting ability of primed plates with primers from group 1 is superior to the group 4 primers, while groups 2 and 3 are roughly equivalent and comprise an intermediate group.
When it comes to the amount of adhesive slag, a shop primer can have either a positive or a negative effect depending on type, film thickness and plate thickness. An important consideration in this respect is that it is the shop primer on the underside of the plate that influences slag adhesion. |
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