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Explore our premium machinery and materials designed to ensure clean, precise, and highly durable rail joints.
In modern railway construction, the traditional jointed track, connected by fishplates and bolts, is increasingly being replaced by Continuously Welded Rail (CWR). The primary objective of this transition is to eliminate the gaps between rail ends. These gaps produce the classic "clickety-clack" noise, but more importantly, they act as points of severe mechanical stress, leading to rail end batter, accelerated wear on rolling stock, and high maintenance costs. Among the various methods of joining rails in the field, aluminothermic welding rail for rail jointing remains the most versatile, reliable, and cost-effective technology globally.
Aluminothermic welding—often referred to as thermit welding—utilizes a highly exothermic chemical reaction between iron oxide and aluminum powder to produce molten steel. This superheated liquid steel is poured into a sand mold clamped around the rail gap, effectively melting the parent rail ends and fusing them into a singular, continuous structure. Because it requires no external electrical power source, thermit welding is uniquely suited for remote track installations, rapid overnight maintenance windows, and complex track geometries where heavy flash-butt welding machinery cannot gain access.
How specialized thermit welding portions and precision equipment meet the rigorous demands of global rail networks.
High-speed lines demand absolute geometric precision and microscopic tolerance levels. Any weld misalignment can lead to high-frequency vibrations at speeds exceeding 300 km/h. Our specialized alignment tools and high-purity portions ensure that the welded joint exhibits identical hardness and wear resistance to the parent rail, preventing localized corrugation.
Freight lines carry extreme axle loads (often exceeding 30 tonnes per axle). The rail joints are subjected to massive shear and compressive stresses. Aluminothermic welds for these scenarios are formulated with specific alloying elements like chromium and manganese to enhance yield strength and prevent plastic deformation under heavy loading cycles.
Urban transit systems feature tight curves, frequent braking zones, and underground tunnels. Space is extremely restricted, and maintenance windows are limited to just a few hours overnight. The portability of RMTS thermit welding kits allows rapid mobilization, execution, and grinding, ensuring the track is fully operational before the morning rush hour.
The core chemistry of the aluminothermic process involves the reduction of iron oxide by aluminum: Fe2O3 + 2Al → Al2O3 + 2Fe + Heat. The reaction inside the crucible reaches temperatures exceeding 2500°C. The resulting molten steel settles at the bottom of the crucible due to its higher density, while the aluminum oxide slag floats to the top. When the crucible taps, the molten steel flows into the mold, preheated to approximately 900°C to 1000°C. This preheating is crucial; it prevents thermal shock and guarantees a complete metallurgical bond by melting a thin layer of the parent rail end face.
Achieving a high-quality weld requires precise control over the cooling rate. Rapid cooling can lead to the formation of brittle martensite, while excessively slow cooling might result in coarse pearlite with lower wear resistance. By utilizing high-quality sand molds and thermal insulation hoods, track engineers can control the cooling curve, ensuring a fine pearlitic structure that matches the wear rate of standard carbon-manganese rails.
RMTS is a manufacturer specializing in railroad thermit welding materials, based in Tianjin, China. With a factory spanning 5,500+㎡ and 30+ professionals dedicated, we are committed to delivering reliable and efficient thermit welding solutions to clients across the globe. Our products are designed to meet the highest industry standards, ensuring durability and performance in various applications.
We understand that successful welding projects require not only high quality products but also expertise and knowledge. That’s why we offer comprehensive on-site training programs to help our clients master the thermit welding process, enabling them to achieve optimal results and build a strong reputation in their respective fields. Additionally, our experienced team provides project welding instruction services, offering hands-on guidance and support to ensure seamless execution, no matter where the project is located.
Driven by a customer-centric approach, RMTS is dedicated to fostering long-term partnerships by delivering exceptional products and services tailored to the unique needs of our clients. Whether you are looking for reliable thermit welding materials, expert training, or project support, RMTS is your trusted partner in achieving welding excellence.
RMTS Production and Testing Facility in Tianjin
Driving innovation in rail welding technology through continuous research, academic collaboration, and field testing.
RMTS have 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 strengthens 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.
Advanced crucible technologies designed to optimize purity, reduce waste, and streamline trackside operations.
Designed for single-use applications, ensuring zero cross-contamination and consistent metallurgical properties. It eliminates the need for crucible cleaning and preparation, significantly speeding up field operations.
Engineered with advanced refractory materials to withstand multiple reaction cycles. This technology reduces the cost per weld and minimizes the environmental footprint of large-scale railway construction projects.
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 ignitor are the main consumables for aluminothermic welding. Each weld requires exactly one complete set of consumables (1 weld = 1 set of consumables).
Formula: (Total Distance / Rail Length) × 2 = Total Sets Required
Example: For a 10km track construction project using 12.5m standard rails:
10,000m / 12.5m × 2 = 1,600 sets of consumables are required to complete the rail jointing.
Proper logistics planning is critical for large-scale railway projects. Thermit powder and refractory sand molds are highly sensitive to moisture. A single drop of water can ruin the chemical reaction, leading to porosity or weld failure. Therefore, calculating the exact number of portions required and arranging for climate-controlled on-site storage containers is essential. Our team provides detailed logistical support, ensuring that consumables are delivered in phased batches corresponding to the track laying schedule, preventing prolonged exposure to environmental humidity.
Comprehensive guidelines for the storage, handling, and execution of aluminothermic rail welds to guarantee maximum track longevity.
Aluminum thermite welding, also known as aluminothermic welding or thermit welding, is a specialized welding technique that utilizes a chemical reaction to generate intense heat for joining aluminum and steel components. Over the past century, this process has evolved from a basic repair technique to a highly controlled, automated rail jointing system used on high-speed rail lines worldwide.
Preparation: Step 1: 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. Step 2: Apply the sand mold and seal the edges with luting sand to prevent leakage. Step 3: Preheat the rail ends. Step 4: Ignite the thermit portion and pour the molten steel. Step 5: Shear the excess weld metal and grind the surface flat.
Thermit welding materials will fail if exposed to water. All welding materials must be kept away from any moisture in storage, as well as during the welding process. Store portions in a dry, ventilated warehouse, stacked off the ground on pallets. Never conduct welding operations during heavy rain or snow unless adequate protective shelters are established over the weld site.
Our complete line of high-performance tools, consumables, and machinery designed for professional track maintenance and installation.
