Notch Formation Mechanism in Low-Speed Oxygen Gas Cutting

The notching phenomenon, which is likely to occur in the low cutting speed range, makes a barrier in cutting thicker plate. Notches are often formed accidentally in practical cutting but they are an intrinsic unstable combustion reaction at very low cutting speeds. Some fundamental research shows that notching in low-speed cutting is characterized by the periodic combustion and extinction at the front cutting wall; the phenomena are greatly influenced by the flow characteristic of the O jet, behavior of the thin molten layer at the front wall and thermal stability at the upper part of the plate. The detailed observation of phenomena and mechanisms of extinction and its propagation, recombustion and self-sustaining condition of periodic phenomenon are described.--AA