Welding Technology
Welding: used machines, accessories & rotary tables
What are welding machines used for?
Welding machines are used to permanently bond workpieces together. They are mainly used for the processing of metal, but they have also found their application in the welding of plastic. There is a difference between welding machines and the welding equipment, where welders can be counted in. Welders are a component of a welding machine, which are mobile and can be used separately as well. Most of the classic welding machines are stationary, as they are used for mass production and normally installed on a specific spot in a production line. The type and composition of a welding machine are usually determined by the thickness of the workpieces it will be processing.
How does a welding machine operate?
A welding machine works using a thermal melting process on two surfaces. The melting process is done either on a specific spot or along a seam on the workpieces' surfaces and it is pressed together using high pressure, before cooling down and solidifying. This results in a permanent and substantial bond between the two workpieces, which can only be reversed if the workpiece is destructed. Other uses of welding include build-up welding and closing up of holes. For these purposes, hand-held welding equipment is used instead of welding machines.
Used to permanently bond workpieces together
Mainly used for the processing of metal
Type usually determined by the thickness of the workpieces
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Different types of welding machines
There is a large variety of welding machines and processes, which differ in their application and the necessary qualifications for their use. When it comes to different types of welding machines, the most commonly used ones are:
Spot welding machine
Arc welding machine
MIG welding machine
Gas welding machine
TIG welding machine
Submerged arc welding machine
Inverter welding machine
AC/DC welding machine
The use of welding machinery in a variety of processes
The welding machinery listed above is used in a variety of welding processes, the simplest probably being spot welding, performed with the use of a special machine. This process, along with electrode or arc welding, is used in the mass production of thin-walled metal products. Here, specially moulded pre-products are fixed onto the welding press and welded onto one another with melt-flows. In addition to the classic spot welding machine, a spot welding gun is used for big and complicated products, such as automobile bodies. In combination with industrial robots, spot welding machines can be a very efficient way to automatically bond metal products together.
MEGATRONIC Welding machine in use
Arc welding machinery
Arc welding is a process of joining one metal to another with the use of electricity, by creating enough heat to melt the metal, which, after cooling, results in the binding of the two melted metals. An arc welding machine uses a power supply to make an electric arc between the base material and the electrode, in order to melt the metals at the welding point.
A special type of arc welding is submerged arc welding. A submerged arc welding machine is used for the processing of very thick-walled workpieces, for example, large tubes or pipes. During this process, a powder made out of iron oxide is put upon the welding spot instead of using a shielding gas. This is a complicated process and the submerged welding machines should only be used by skilled workers with high qualification and experience levels. Generally, the submerged arc welding process is characterized by a very comprehensive quality control. During the different work steps in the use of a submerged arc welding machine, the fatigue strength of the welded seal is regularly checked.
Electric welding can be performed using further special types of welding machines – such as an inverter welding machine, or AC/DC welding machine. The main advantages of an inverter welding machine, when compared to the conventional one, are its small and compact size and lower power consumption.
The terms AC (Alternating Current) and DC (Direct Current) depict the polarity of the electrical current, which is being produced by a welding machine and which passes through the electrode. An AC/DC welding machine, as opposed to a conventional AC welder, has the capability of employing both alternating and direct current.
Gas welding machines are used to bring the base material to a melting point with an oxy-acetylene flame. At the same time, a filler rod is introduced that is continually being melted. This process is particularly useful for build-up welding to close up openings, unevenness or gaps in the material. A gas welding machine is also particularly applicable in the welding of cast iron. Gas shielded welding is, along with arc welding, the most widely used process. Through a continual emission of shielded gas, oxygen is prevented from reaching the welding spot, as that would result in burn holes. Gas shielded welding machines can either be hand-held or fully automatic. During this welding process, one can choose between using metal inert gas welding (using an MIG welding machine), metal active gas welding (MAG) or wolfram-inert-gas welding (WIG).
Where to find a quality second-hand welding machine?
Some of the well-known welding machine manufacturers are MESSER, ROTH, WALTER and KIEHNE. Although it is possible to find simple used welding machines for a price of a few hundred euros, some of the more complex used welding machinery can cost more than ten thousand euros. High-quality used welding machines for sale are offered by Surplex on a regular basis, and it is often possible to buy them at competitive prices in our numerous industrial auctions.
