Aluminothermic Welding
Aluminothermic welding, also known as thermite welding, is a highly efficient welding process that uses an exothermic chemical reaction to join metal parts. It is widely used in rail welding due to its ability to create strong, durable, and reliable joints without the need for an external power source. This method is especially suited for joining railway tracks, where consistency, strength, and longevity are critical.
How Does Aluminothermic Welding Work?
The process relies on a thermite reaction—a chemical reaction between aluminum powder and a metal oxide (usually iron oxide). When ignited, this reaction produces intense heat and molten steel, which is then poured into a mold surrounding the rail ends. The molten metal fuses with the rail ends, and upon cooling, forms a solid, continuous joint.
Key Steps in the Process:
Rail Adjustment & Alignment – Ensuring the rails are properly positioned.
Gap Setting – Maintaining a precise gap (typically 26±1 mm).
Preheating – Using a preheater to bring the rail ends to the required temperature.
Mold Setup – Installing the welding sand mold around the joint.
Ignition & Pouring – Igniting the thermite and allowing the molten steel to fill the mold.
Cooling & Finishing – Removing excess material (de-tumoring) and grinding the weld to match the rail profile.
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