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In modern railway engineering, the continuity and geometric integrity of the rail profile at jointing locations are fundamental to the safety, speed, and efficiency of rail transport. A rail joint—whether mechanical, insulated, or welded—presents a structural discontinuity in the track. If the rail profile is not perfectly matched and maintained across this joint, passing trains experience dynamic shock loads. These impacts accelerate wear on both the rolling stock and the track infrastructure, leading to localized degradation, noise pollution, and potentially catastrophic structural failures.
Whether dealing with standard Vignoles rail profiles, crane rails, or light transit lines, the jointing process requires absolute precision. The rail profile consists of three key zones: the head, the web, and the foot. During jointing processes such as thermit welding, the alignment of these zones determines the structural load path. A mismatch in the head profile leads to wheel running surface irregularities, while misalignments in the web and foot compromise the structural integrity under high bending stresses.
The global railway industry is undergoing a rapid transition toward Continuous Welded Rail (CWR) systems. By eliminating traditional mechanical joints (which rely on fishplates and bolts), operators can significantly reduce maintenance costs and increase train speeds. However, the creation of a seamless CWR track relies entirely on field jointing techniques, with aluminothermic (thermit) welding serving as the primary method for on-site track assembly.
Heavy-haul lines carry axle loads exceeding 30 tons. At these extreme loads, any minor rail profile mismatch at a joint causes massive dynamic forces, leading to plastic deformation of the rail head. Precise profile grinding and robust jointing materials are mandatory.
For trains operating at speeds over 250 km/h, joint geometry tolerances are strict. Mismatches of even 0.3mm can cause passenger discomfort and trigger safety system alerts. Seamless jointing with custom-profile sand molds is essential.
Metro networks operate under tight curves and high-frequency schedules. Noise and vibration mitigation are critical in urban environments. Precisely aligned welded joints are key to reducing ground-borne vibrations.
Seaport crane tracks handle extremely high concentrated wheel loads. Jointing crane rails requires specialized weld portions and thick-web profile configurations to prevent joint crushing under load.
RMTS has a highly skilled R&D team that works tirelessly to ensure that we produce thermit welding materials that meet the specific needs of each type of rail.
In addition to its strong R&D capabilities, RMTS actively participates in railway projects across China and abroad. The company collaborates with railway authorities, construction companies, and maintenance organizations to provide its expertise and materials for various projects.
By participating in railway projects, RMTS contributes to the development and maintenance of China's extensive railway network. Whether in high-speed rail, urban transit systems, or conventional rail lines, RMTS offers its thermit welding materials and services to ensure the integrity and safety of the rail infrastructure.
Furthermore, RMTS maintains partnerships with research institutions, universities, and industry experts in China. These collaborations enable RMTS to strengthen its R&D capabilities in thermit welding technologies.
RMTS's strong R&D abilities, coupled with its involvement in railway projects, demonstrate the company's commitment to providing advanced thermit welding solutions that meet the specific demands of the railway industry.
Our main markets are in areas such as railway main lines, seaport crane rails, subways, trams, and high-speed railways. Aluminothermic welding plays a crucial role in these fields. No matter the scenario, RMTS welding technology, with its excellent performance, serves as a powerful support for promoting industry development and ensuring operational safety.
Thermit portion, sand mold, luting sand, and ignitors are the core consumables for aluminothermic welding. Each weld joint requires one complete, dedicated consumable set. Precise matching of the sand mold to the specific rail profile is critical to prevent leaks of molten steel during the reaction.
Because different rail standards (such as AREMA, UIC, or Chinese TB) have distinct cross-sectional geometries, the sand molds must be manufactured with precise profile tolerances. A mismatch between the mold profile and the rail profile will lead to flashing, incomplete fusion, or weld metal leakage, compromising the safety of the entire track.
RMTS is a passionate and progressive aluminothermic welding manufacturing company, dedicated to supporting our clients throughout the lifecycle of their jointing projects.
Aluminum thermite welding, also known as aluminothermic welding or thermit welding, is a specialized welding technique that utilizes an exothermic chemical reaction to generate intense heat for joining steel rail components.
Preparation: Ensure the rail ends to be welded are clean, free from rust, and properly aligned. The gap size (space between two rails to be welded) shall be 26±2mm.
Thermit welding materials will fail if exposed to water. All welding materials should be kept away from any moisture in storage, as well as during the welding process.
Thermit welding, also known as aluminothermic welding, requires careful handling and storage of its materials to ensure safety and optimal performance.
We offer a wide range of thermit welding materials, such as welding kits, sand molds, one-shot/long-life crucibles, luting sand, and ignitors, ensuring consistent quality and reliable performance.
Achieving a high-integrity welded joint requires a systematic combination of heavy machinery and precise consumables. The process starts with cutting the rail ends square using a high-precision electric rail cutting machine. Any deviation from a square cut can result in uneven heat distribution during preheating.
Once cut, the rails must be aligned vertically and horizontally. This is where the high-capacity bidirectional rail joint adjuster is used, correcting any alignment errors in the rail profile. If the rail is under thermal stress, a hydraulic rail tensioning machine is deployed to maintain the proper weld gap (26±2mm) during the process.
After the thermit reaction occurs and the molten steel is poured, the metal solidifies inside the sand mold. The next phase is critical: the excess weld riser must be removed. A rail shearing machine shears the hot excess metal close to the rail profile. Finally, once cooled, a profile rail grinding machine restores the running surface, ensuring a smooth transition across the joint.
