WELDING - METHODS AND THEIR CHARACTERISTICS
By the simplest definition welding involves permanently joining fusible materials by local melting and then solidifying them in the presence of a binder. Mainly metals (steel, aluminium, copper, nickel, titanium) and plastics.
- Welding methods
There are many different welding methods, but we will only discuss a few of the most popular. These are as follows:
- Electric welding
Probably the most common and technically simplest method based on the arc phenomenon. It is carried out at temperatures of up to 4000°C. It is used to weld relatively thin metal sheets - i.e. those between 1 and 80 mm.
- MIG/MAG welding (Metal Active Gas/Metal Inert Gas)
Welding with consumable electrodes shielded by active gases (MAG), usually carbon dioxide or mixtures thereof. MIG welding is carried out in argon or helium. Commonly used in automatic and semi-automatic processes.
- TIG welding (tungsten Inert gas)
Also known by the acronym GTAW - Gas Tungsten Arc Welding. As in the previous example, this is done in an inert gas, the difference being that the electrode is non-fusible and made of tungsten. The main advantage of this method is the wide range of material thicknesses to be welded and the rather insignificant potential disadvantages of using it.
- Types of welds
A weld is to welding what a seam is to the sewing industry. Therefore, the durability of the final structure is based on it. Here are examples of types of welds and their applications:
- Face welds
They are formed by joining the wall of an element (thickness) with another material. Most commonly used for sheet metal, bars and pipes.
- Edge joints
Basically, no other materials than welded ones are needed to form the edge welds. All that is needed is to bend the edges accordingly and heat treat them. The method is commonly used for thin sheets.
- Fillet welds
As the name suggests, they are ultimately used to join components which are offset from each other. A welded joint can be either a lap or overlap joint, depending on the way the plates overlap.
Other important issues for the welder include welding positions. These are known by their letter abbreviations (PA, PB, PC etc.) and refer to the details of the welding process. For example, whether the filler metal is applied from the bottom up or vice versa. Two items fall out of the above naming scheme: H-L045 and J-L045, which stand for fusion of pipes in a 45° inclined position from bottom to top and top to bottom.
In addition, parameters such as changes in the material or geometrical welding discrepancies, etc., are distinguished. To diagnose these, a number of appropriate tests and examinations are carried out. However, in order to be able to weld at all, one must first obtain the appropriate certificates from UDT - NSPAW. Below you will find links to proven training centres.