If manual arc welding is used, the first thing is to distinguish between hot metal and leather. Observe molten pool: the molten liquid is molten iron, and floating on it is the skin of medicine. Attention should be paid to the welding. The skin should not be allowed to exceed the molten iron, otherwise it is easy to slag. It is necessary to control the welding rod with the hand to adjust the angle of the electrode. And if you feel the way, you can use a large amount of current, because the large current can better distinguish the skin and molten iron, the welding is more transparent, but it must be controlled. Welding vertical welding is smaller than flat welding current, while welding is smaller than vertical welding current. When welding, find a posture that is comfortable and can weld the weld once. Learn to control the welding handle with your wrist. If it is carbon dioxide welding, the first thing to pay attention to in the process of welding must always observe the molten pool, and that is, the best use of one element control, gas flow is generally 18-20. If there is no one element control, it should be adjusted according to the welding process. If the welding wire is not melted or melted, the voltage should be enlarged or the current is small. If the wire is melted in large drops or the pool area is too large, the voltage is too high. If the tungsten electrode is similar to the two oxygen welding, it is also necessary to note that the length of the tungsten electrode should not be too long, and the tungsten head shape should be maintained. Note that welding can not operate in a windy place, and has a great influence on the welding quality. It is necessary to ensure the cleanliness and safety of the welding parts.