The combustion of both gasses from the welding nozzle can be divided into 3 characteristics according to the mixture ratio as follows:
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- Carburizing Flame
- Neutral Flame
- Oxidizing Flame
- Carburizing flame caused by the combustion of both gasses But acetylene gas is more than oxygen gas. The combustion of this type of flame is acetylene gas will not burn completely. If welding in a room or place Confined spaces without ventilation can be dangerous. The heat generated by this type of flame is lower than 3,200 degrees Celsius. It is commonly used for welding metals with low melting points such as lead, aluminum, and others. The remainder from the combustion will act like a welding flux. Prevent oxygen gas from joining the welding line. Notice that the flame has 3 layers.
- Middle flame is caused by the combustion between oxygen gas and acetylene gas from the welding nozzle in the ratio of 1 to 1. It can be observed that the flame has 2 layers, the inner layer is white and bright blue after the tip of the tip, the outer flame surrounds Round is a long pointed cone. This type of flame has a maximum heating temperature of 3200 ° C. The hottest position is approximately 2 – 10 mm from the inner flame, depending on the welding nozzle size. This type of flame is commonly used for welding general metals.
- Oxidizing Flame is a flame with more oxygen gas than acetylene gas, the combustion of this gas will have residual oxygen gas And it is clearly noted that this type of flame has only two layers, a small and shriveled inner flame attached to the tip of the tip. The outer flame is light blue. The temperature of this type of flame is slightly lower than that of the medium flame. It is commonly used for welding metals of the bronze type because it will keep the properties of the bronze unchanged. If this type of flame is used to weld ductile iron, bubbles will occur. The melting pond is not clearly visible. brittle weld and porous, not strong
welding head cooling While welding for a long time, the welding nozzle becomes hotter than normal. To cool the welding nozzle, it is possible to immerse the welding nozzle in a tank of water. Close only the acetylene gas valve and the oxygen gas section. open as before The welding nozzle may be immersed in the water tank up to the joint between the welding nozzle and the hand to cool all parts. shake the welding head Setting the welding head angle and feeding the welding wire
When welding the workpiece, the head angle must be set. Weld to lean back about 30 – 45 degrees to the work surface and make right angles to both sides. The welding head is high from the work. There is a distance from the tip of the inner flame to the work surface about 2 – 10 mm, depending on the size of the welding head.
In every welding, flames must be used to burn the workpiece in the area to be welded until it melts into a round basin. Also known as the melting pond (Puddle), which is the hottest part, after that, shake the welding head slightly to heat. to the workpiece thoroughly When the workpiece is melted into a melting pond, then the welding rod is added to the solder. The workpiece oscillates the welding head while moving slowly, evenly, trying to maintain the oscillation distance and wire feed. connected to each other all the time There are many types of oscillation of welding wires. The welder can choose any oscillation as he is comfortable with, but the width must be suitable for the size, thickness and joint of the workpiece.
If the welding head is shaken wide, the resulting melt pond will be large. and very deep in the workpiece, deep integration in The weld workpiece will be better. If the workpiece is thick, the melting pond must be wide as well. If the workpiece is thin, the weld head oscillation must be narrowed so that the melting pool is small. If the welding head is wobbled too wide, a lot of heat will accumulate, causing the workpiece to pass through. Therefore, the oscillating welding head must be related to the workpiece. and the nature of the joints
