The different welding methods
The most used welding method, from the dawn of civilization until a little over a century ago, consisted of heating the pieces of metal to be joined, bringing them to a yellow-white glow, to subject them to continuous hammering until melting them together. It was only in 1895 that it was possible to develop the method based on the combustion of a gas mixture, in particular oxygen and acetylene, in order to create a thermal lance capable of bringing the metal to melting temperature in a short time.
The main obstacle to the implementation of new welding methods, therefore, has always been the enormous amount of energy required to bring the metals to their melting temperature. With the spread of electricity, therefore, it was possible to develop new more effective and faster welding methods.
The most used welding systems nowadays, in fact, are precisely those with the electrode and continuous wire, powered by electricity, which now finds a wide range of applications both in the professional and hobby and domestic sectors.
Which welding machine to buy
From an economic point of view, the expenditure varies slightly, once the type of plant to be purchased has been identified, in fact, choosing the specific model becomes quite easy. Professional welding systems have a cost ranging from 1,000 to 1,500 euros and more, depending on the type, while hobby ones can vary from 100-200 up to around 800-900 euros.
The substantial difference lies in the welding methods made possible by the system; some models, in fact, are designed to weld with both electrode and continuous wire, while others are more specific, therefore there are systems that weld only with electrode and others that weld only with continuous wire. As the method changes, the degree of skill required by the welder also changes.
It should be remembered that electrode welding is easier to perform, especially for a beginner than continuous wire welding which requires superior skill and coordination of the hands. Those who do not have particular needs, therefore, can safely buy an electrode welding machine, which is also cheaper as well as easier to manage.
There are also specific welding machines for precision use, they are always electric welding systems but with minimal installation power and extremely small dimensions. Their use, however, is limited to specific professional figures, dedicated to precision work; just to give an example, in fact, they are used to perform the soldering of the components on the electronic boards, or to solder together the electric cables and the relative control panels, switches and sockets.
The relative welding methodology involves the use of tin as filler material; the latter has a low melting point so the power absorption of these welders, as mentioned before, is limited to a few tens of watts, usually from 30 to 80 depending on the model chosen.
Apart from electrical engineers and electricians, tin solders are also used by goldsmiths, jewellers, dental technicians and precision mechanics, while in the hobby field they find various applications in model making and in small home repair jobs.
Welding defects and how to avoid them
It is good to remember that buying an excellent welding machine does not automatically make you immune from welding defects, which in turn change according to the method used. Electrode welding, for example, is much more subject to the defect of slag intrusions in the welding bath, since the coating of the rod tends to flake when it melts, thus releasing microscopic particles that often end up incorporated in the molten metal .
Wire welding, on the other hand, is more subject to cracks, that is, micro-lesions in the weld seam due mostly to sudden thermal changes in the weld pool; other defects that may occur are the excessive or insufficient penetration of the filler material, which leads to the formation of porous layers and is always linked to the heat input, and contaminations from oxides when the welding bath is not adequately protected from gas.
Whatever the welding defects that may occur, the best way to avoid them is to have a thorough knowledge of the method used and to develop a high degree of manual skill.
Use the welder to cut
When it comes to welding machines, in general, the first application that comes to mind is that of the union of metal pieces aimed at the construction of different objects. It should not be forgotten, however, that since the welding machines develop a heat that melts the metal, they are perfectly capable of cutting it as well as joining it.
Before we mentioned the oxyacetylene welding method, which instead of electricity uses the combustion of a mixture of oxygen and acetylene; this welding method was introduced towards the end of the nineteenth century, and was used intensively only during the first two decades of the twentieth century, when the first electric welding plants began to appear. Since 1925, in fact, oxyacetylene welders have been used less and less for welding, and nowadays they are used only marginally and in hydraulics for this purpose, for connecting pipes and for creating pipes and collars.
Their efficiency in reaching high temperatures in relatively short times by simply adjusting the proportion of oxygen and acetylene, however, has made them particularly suitable for cutting operations, which they carry out more quickly and easily than with electric arc welding machines. Consequently, oxyacetylene welders are mainly used on construction sites for the demolition of large iron and steelworks.