Welding is the process of permanently joining two or more parts under heat, pressure or both when the parts have cooled. It is commonly used with metals and thermoplastics, but can also be used with wood. In welding, the starting material is the parts that are not joined together. The consumable (filler material) is called the material added to form the joint. It is desirable to select it so that it resembles the base material in terms of composition. The main factors that are important for the final result are the appropriately selected type of welding and filler material. Equally important is the determination of the melting and fusion times of the materials.
Types of welding:
- Laser - This method is one of the latest welding methods. It involves fusing objects through heat obtained from a very high-density coherent light beam. It is used for joining workpieces of different shapes. The strengths of laser welding are its high precision, cleanliness, speed of the process and ease of automation.
- Gas - is a method in which materials are joined by heating and melting their edges using a burning gas flame. Very often acetylene is used as the fuel gas, rarely hydrogen or propane. Gas welding is usually used for renovation work and the welding of thin pipes, for example water pipes, gas pipes. The advantages of this method are the low cost of the equipment, the large range of thicknesses welded, the relatively easy welding technique and the speed and productivity.
- Termite - a method that uses a chemical reaction as a heat source, which involves the combustion of thermite, a mixture of iron oxide and aluminium. Thermite welding is used in the repair of railway rails, casting defects or broken pivots. This type of welding is fast, simple and efficient.
- Electric - This is a method which uses an electrode or electric arc. It involves joining metals using an electric welding machine. Heat is generated in an electric arc, which is created in the gap between the electrode and the object to be welded. It is most commonly used in locksmithing, artistic blacksmithing and when joining large components. The main advantages are the ability to join steel components, repair cast iron components, high weld strength and economy.
Which binder to choose?
The use of a filler metal is also an important part of welding. There are several factors that are particularly important in its selection, such as welding position, type of material and shielding gas to be welded, post-weld heat treatment and welding equipment. The filler metal is an additional material used to minimise the risk of cracks or damage. Therefore, it is very important that it is properly selected and has the right mechanical and chemical properties to ensure its durability under different working conditions.