Primer is very important when cutting steel plate with flame cutter. The primer is too small and the steel plate heats slowly. The primer is too big, and the incision is radian, which is not beautiful. When the primer becomes an oxidation flame, the temperature of the high-temperature steel plate will rise rapidly, but at the same time, an oxide layer will be produced on the surface. The upper metal melts and the incision is not beautiful. When the primer becomes a carbonized flame, the temperature is low and it is not easy to generate heat. Priming adjustment principle: first turn on acetylene (liquefied methane, liquefied petroleum gas), then turn on preheating oxygen slightly, and ignite the mixed gas at the cutting nozzle. Because the preheating oxygen is rarely turned on, the flame is orange at first, and then the preheating oxygen is gradually turned on, and the flame gradually turns from orange to blue. At this time, you can see that the flame center in the center of the cutting nozzle gradually changes from large to small until the flame center receives the root of the cutting nozzle. This is the most appropriate time. As for the size of the flame, it depends on the thickness of the cut iron plate. The thicker the iron plate, the greater the flame. Cutting: Place the preheated flame on the edge of the cutting iron plate, heat the edge to red, and then turn on the cutting oxygen (high pressure air in jargon). When oxygen meets red-hot iron, it will burn quickly and melt iron. Due to the high pressure of cutting oxygen, it will blow away the molten iron and form a cutting gap. Cutting oxygen should not be too small, too small will form molten iron slag on the back or can not be cut through, and too large cutting oxygen will cause waste. It would be nice to hear a "poop-poop" sound under the iron plate when cutting oxygen. If you want to make a beautiful incision, you should keep practicing. Practice makes perfect.