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Learn about flames used in gas welding

Gas welding is another method that is very popular today. Welding usually uses flames generated by the combustion of fuel gas and air. 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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  1. Carburizing Flame
  2. Neutral Flame
  3. Oxidizing Flame
  4. Carburizing flame caused by the combustion of both gasses But acetylene gas is more than oxygen gas. The combustion of this type of flame, acetylene gas will not burn completely. Welding in a room or a confined space without ventilation can be dangerous. The heat generated by this type of flame is below 3200 degrees Celsius. It is commonly used for welding low melting point metals such as lead, aluminum, etc. In addition, the residual carbon from combustion acts like a flux covering the line. link Prevent oxygen gas from pooling in the weld. Notice that the flame has 3 layers.
  5. Neutral Flame is caused by combustion between oxygen gas and acetylene gas from the welding head 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 is enclosed in a long, pointed cone. This type of flame has a maximum heating temperature of 3200 degrees Celsius. The hottest position is about 2-10 mm from the inner flame, depending on the size of the welding head. This type of flame is commonly used for welding general metals.
  6. Oxidizing Flame It 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 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 middle flame. It is commonly used to weld metals of the bronze type because it keeps 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 head will be hotter than usual. Cooling of the welding nozzle is achieved by immersing the welding nozzle in a tank of water. Close only the acetylene gas valve while the oxygen gas is open as usual. 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 at 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 approximately 2 – 10 mm. according to the size of the welding head.

In every welding, the flame must be used to burn the workpiece around the line to be welded until the heat is melted into a round basin known as the melting pond (Puddle), which is the hottest part. After that, shake the welding head slightly to heat. the workpiece thoroughly When the workpiece is melted into a melting pond, then the welding wire is added to form the workpiece. Shake the welding head while moving slowly and steadily. Try to keep the oscillation distance and the wire feed relative to each other at all times. There are many types of oscillation of the welding wire, the welder can choose any oscillation according to his/her ability. But the width must be suitable for the size, thickness and joints of the workpiece.

If the welding head is shaken wide, the resulting melt pond will be large. and very deep in the workpiece The deeper the weldment in the workpiece, the better. If the workpiece is thick, the melting pond must be wide as well. If some work The oscillation of the welding head must be narrowed so that the melting pool is small. If the welding head is oscillated too wide, a lot of heat will accumulate, causing the workpiece to pass through. Therefore, the oscillation of the welding head must be related to the workpiece. and the nature of the joints

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