The main types of welding

 

The main types of  welding

Non-arc welding is more often called contact welding. In contact welding, the electrodes that supply current are applied directly to the metal that is being welded. A short, but very powerful current discharge (thousands of amperes) is applied through the metal located between the attached electrodes. In this case, fusion is obtained only between the applied electrodes.

 If the electrodes are located directly opposite each other, then the welded joint is obtained point-wise. Although spot welding is not the only type of contact welding, but it is the most common.

 Therefore, the concepts of "spot welding" and "contact welding" are often used as synonyms. The voltage of spot portable welding machine is a few volts. Therefore, contact welding is used mainly for bonding sheet metal. For example, in the automotive industry.

 In construction, electric arc welding has become much more widespread. In electric arc welding, there is a small gap between the current source (electrode) and the metal being welded, which is filled with an electric arc. 

It is a mistake to assume that this is a gap of air. This is a gap of ionized gas conducting a current. 

Arc welding, as we imagine it today, is impossible without gas. Simply, the gas can be supplied from a separate cylinder, or it can be formed as a result of burning of the electrode coating.gorenje

 The most common technologies in construction are the following:

 MMA (in the domestic classification – manual arc welding, or RDS)

TIG (argon-arc)

MIG-MAG (semi-automatic, wire).

MMA

The popularity of this type of welding is predetermined by the lack of the need to carry a gas cylinder with you. The coating of the electrode is a "frozen" gas cloud. As soon as the electrode touches the metal and the resulting short-circuit current melts the metal of the electrode, the coating around it will also melt. The resulting gas cloud will provide a conductive ionized medium for the arc and protect the molten metal from oxygen access.

 The electrodes are selected according to the type of metal and diameter. The type of metal is important, since during the operation of the metal rod of the electrode, drop by drop flows into the metal being welded and is fused with it. 

For a strong connection, the metal of the electrode rod and the metal being welded must be identical. On the packaging of the electrodes, it is always indicated for which metals these electrodes are suitable.

 After you have decided on the type of electrode, you need to decide on its thickness. 

A beginner's question: why do we need electrodes of different diameters? It's simple. 

The thicker the electrode, the greater the current strength that can melt it.

 The same is true with the edges of the metal being welded. Therefore, the thickness of the electrode is selected for the thickness of the metal being welded. For ferrous metals, it is recommended:

 MMA technology allows you to work with most common metals, with the exception of aluminum and alloys based on it. 

Although theoretically this is also possible if there is an assistant, if you ensure that the cleaned aluminum surfaces do not have time to be covered with a film before melting.

 But it is more correct, of course, to simply use suitable welding technologies for this.

 TIG

Consumers of TIG welding are entirely professionals and advanced users, and almost completely not in the construction direction. TIG provides more accurate seams, but is much inferior to MMA in performance and ease of use.

 For example, many "amateurs", having honed their skills on MMA machines, are annoyed by failures during their first experience with TIG.

 It turns out that, unlike MMA, it is not easy to light an arc with a TIG device, unless it is equipped with such a device as an oscillator. (And almost all "2 in 1" devices are not equipped, of course). 

The welder strikes a tungsten electrode – there is a spark, but it is impossible to raise the arc.

 But now an experienced welder puts a piece of coal under the electrode – and the arc went without problems. It is no coincidence that in the sales of retail stores, specialized TIG devices rarely exceed a share of 1%.

 Devices with the ability to switch to the mode of alternating welding current, the so-called AC/DC, deserve a special mention in TIG welding.

 These devices are the main equipment for welding aluminum. They mainly make up this very 1% of TIG in retail sales of welding equipment.

 MIG-MAG

Semi-automatic wire welding is mainly used for sheet metal welding. Therefore, traditionally its main scope of application is body repair, as well as the construction of structures made of black thin-sheet metal.

 Using a wire instead of replaceable electrodes greatly increases productivity. Household appliances use coils with a capacity of 1 and 5 kg, and professional ones-5 or 15 kg.

 The wire can be used both ordinary (without coating) and with coating (so-called flux). In the first case, it is mandatory to use a gas cylinder (GAS mode).

 In the second case, the cylinder is not required (NO GAS). Despite the fact that it is more convenient to work without a balloon, the wire without coating leads in sales by a large margin.

 The reason is banal: it is much cheaper than flux. In addition, many professionals believe that the accuracy of the seams in the gas environment from the cylinder is higher.

 Despite the fact that this type of welding also refers to electric arc welding, the principle of the MIG-MAG device is fundamentally different from the principles of MMA and TIG.

 In MMA and TIG, it is important to maintain the stability of the current, despite the fluctuations of the electrode, in MIG-MAG, it is important to maintain the stability of the arc voltage.

 And the strength of the welding current in MIG-MAG devices is a conditional indicator (although, according to the habit developed in MMA, most people focus on it).

 The strength of the welding current in the MIG-MAG will depend on the voltage set, the diameter of the wire used, the gas used and the wire feed speed. 

So it will not be possible to make a MIG-MAG semi-automatic machine from the MMA device by attaching a wire feed unit and a burner.