Exothermic welding is a chemical process which enables the molecular bonding of metals in a long-lasting way. It is applied to metal joints and its use is very widespread in sector such as rail and the electrical sector, in the grounding connections.
In this article, we will develop the evolution of exothermic welding since its invention in 1893 to the current innovations, which have meant important improvements in the process.
Exothermic welding: from invention to innovation
The exothermic welding is based in a termite reaction which was discovered in 1893 by the German chemist Hans Goldschimdt, taking as a starting point the studies of Bekétov. Hence, the aluminothermic is known as the “Goldschmidt reaction”. In 1895. Goldschmidt had developed the process and patented it in Germany.
Years before, between 1859-1865 in the Járkov university (Ukrania) the Ukrainian Nikolai Bekétov started to observe the reaction of aluminium from its oxides which were exposed to high temperatures. These investigations were very relevant since they laid the foundations that led to the subsequent invention of aluminothermic welding.
The first commercial application of the aluminothermic reaction for iron was in 1899 and consisted of welding sections of railway tracks in Essen (Germany). This was exported to the American continent, where its use was extended. Due to the commercial interest, John H. Deppeler patented it in the United States.
As for copper, in 1939, Charles Cadwell made his first non-ferrous application for welding, applying it to electrical connections. In his honor it was called, at first, Cadweld welding. The procedure and format practically did not evolve for years. It has been in this last decade when the most notable innovations have occurred, which have mainly affected the type of loads and ignition, to make the procedure more versatile and safe.
The development and technological innovation of the different manufacturers in the sector have taken the Cadweld process one step further. The Apliweld® system of Aplicaciones Tecnológicas has established itself as the safest and most practical way of the market. For those reasons, day by day more infrastructures around the world use it.
Exothermic welding of copper in the electrical sector
The aluminothermic connections are used as electrical conductor connections. The use of exothermic welding for earthing guarantees electrical conductivity without risk of the connections degrading or deteriorating over time.
In fact, only the unions for exothermic welds are recognized as a form of electrical connection valid by the IEEE, as continuous cable not spliced.
Differences between the powder and the tablet charges for exothermic welding
The powder charges where the first to be invented and commercialized. Nevertheless, due to the inconveniences it could present, Aplicaciones Tecnológicas has made efforts to develop a alternative in tablets, with a successful result.
- The tablet has only one use, two maximum. One of the references is used for the 90% of the unions, and the other one for the big conductors. In the powder format, the multiple references, every one of the different, suppose a clear disadvantage. In this case, it was common that the workers had to carry loads of different grammages. cartridges for exothermic welding of 45g, 65g 90 g, 115 g, 150 g … References are simplified thanks to Apliweld®.
- The tablet format eliminates the difficulties of working with powder: spillover, material loses whilst opening the container, difficulties of working with wind.
- The tablet charges, Apliweld® unique system which reduces the waste to a folding cardboard box, important to minimse the impact of the process in the environment. Every weld accumulates waste from each load.
On the other hand, other systems have offered an electronic alternative like Apliweld® it does, they present the load In tablets and every weld leaves a container in the form of a non-biodegradable waste.
- The tablets can be used in every type of moulds that exist in the market.
To resume, for those who are accustomed to traditional methods of aluminothermic welding, the improvements of Apliweld® represent great advantages.
Exothermic welding kit
To make aluminothermic joints, the necessary exothermic welding equipment consists of the following elements:
Graphite mould
When you need to make many welds of the same type of joint, it is usually recommended to use specific welding moulds. If what is needed is to make few connections of several types of joints, the use of the multiple mould is recommended.
Welding compound in tablets
The charges that are introduced inside the mould to produce the aluminothermic reaction, are presented in easy-to-use tablets and dosed. Each box is composed of 20 tablets.
In each mould, the number of tablets required to make the union is specified.
Electronic initiator system with remote ignition
The exothermic welding with electronic ignition supposes important benefits, the most important one the security it represents. The system consists of a non-flammable electronic initiator and remote ignition equipment. In this way, the flint igniter with flammable powder initiator is replaced by this secure Apliweld® Secure + system.
The biggest advantage is being able to ignite remotely with activation of the reaction via Bluetooth, avoiding the risks of accidents arising from the reaction itself or any error in the preparation of the system.
Clamp for exothermic welding
Depending on the type of mould required, the clamp used in exothermic welding varies. In each mold, the required clamp is specified.
Other accessories for exothermic welding
The safety and cleaning accessories (brushes, gloves, scrapers, etc.) are essential for the realization of any welding. In addition, depending on the joint to be made and the material available, it is possible that other accessories such as sealing paste or any adapter needed.
When buying exothermic welding, it is very important to take into account the quality of the product, solutions that simplify work and logistics, and ensure the safety of workers and the prevention of occupational hazards.
If you want to know more, you can check the videos of our channel on exothermic welding in YouTube.