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Published byGriselda Johnson Modified over 9 years ago
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Fabrication Welding
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Brazing Brazing is where 2 pieces of metal are joined together by melting a DIFFERENT type of metal to form a joint For example steel can be brazed using a brass brazing rod The brazing rod can be melted using a brazing hearth (natural gas and air mixed like a bunsen burner) or by Oxy Acetylene (Hotter)
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Welding Welding differs from soldering and brazing, in that the materials being joined must be the same. If a filler rod is being used then it should be the same material as that being joined. There are a number of different methods of welding including the use of oxy-acetylene or an electric arc to generate the heat required. Other techniques use an electric current passing through the material to fuse them together.
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Oxy-acetylene Welding
This uses a mixture of oxygen and acetylene gas to create a flame that will burn at a temperature of around 2500 degrees Celsius at the hottest point. This will clearly be sufficient to melt mild steel at the joint allowing the melting of a filler rod to fuse the joint edges together.
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Electric Arc Welding This generates sufficient heat to melt the joint edges by creating an electric current through a gap (arc) between the materials being joined and the filler rod (electrode). The electrode is coated in a flux which, when melted, prevents the joint area becoming oxidised.
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MIG and TIG MIG and TIG welding – these are more refined forms of electric arc welding which can be used to join thin sheet material. MIG (Metal Inert Gas) and TIG (Tungsten Inert Gas) welding use a gas jet around the filler wire to prevent oxidation of the material. Different gases are used with different materials, e.g. Argon is used with aluminium. TIG MIG
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Spot Welding Seam Welding Spot
Both spot and seam welding use an electric current as the heat source. Spot welding as the name suggests provides a spot of heat to fuse the metals together. It is usual to find a series of spot welds in a structure like a car body shell. Seam welding, on the other hand, passes an electric current through the material as it passes under the rollers. A typical application for this type of joining method is tin coated mild steel food and drinks cans. Seam Welding Spot
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