Quick guide to various welding methods
1) Manual arc welding (STICK)
Manual arc welding, eng. Shielded Arc Welding (abbreviation SMAW),
The principle is that an arc is formed between the coated electrode and the base material, and the heat from the arc is used to melt the electrode and the base material. The outer layer of the electrode is covered with flux, which melts when heated and performs the functions of arc stabilization, slag formation, deoxidation and refining.
Scheme of manual arc welding
The welding power source is an AC welding machine or a DC arc welding machine with a falling characteristic. Typically, AC arc welders are used, while DC arc welders are used when arc stability is especially required.
Main functions:
Simple welding operation
Welding tongs are light and easy to move,
Wide range of applications
2) MIG welding (CO2/MAG/MIG)
Gas-shielded consumable electrode welding, eng. Gas metal Arc Welding (abbreviation GMAW)
MAG welding: metal Welding with active gas (Active Gas: active gas)
MIG welding: welding metals in an inert gas environment, (Inert Gas: inert gas)
Depending on the type of shielding gas, it can be roughly divided into MAG welding and MIG welding. MAG welding uses CO2 or a mixture of CO2 or oxygen in argon (called reactive gases). The welding habit that uses only CO2 gas is called CO2 arc welding, which is different from MAG welding. MIG welding uses inert gases such as argon and helium.
The principle is that an arc is formed between the thin-diameter consumable electrode (welding wire) and the base metal, and the environment is sealed with shielding gas to melt the base material and the welding wire. It is widely used in semi-automatic welding with operator manual welding torch, robotic welding and automatic welding.
Principal diagram of gas shielded welding
CO2 welding characteristics:
High welding speed
High efficiency arc ignition
Molten bath depth
High deposition efficiency
One welding wire can be used for sheets of different thicknesses
Good welding quality
Slight deformation after welding
One welding wire can be used for many types of base materials
Features of MAG welding:
Beyond the benefits of CO2 welding
The appearance of the weld is beautiful
Less spatter
Double-sided form welding, circular welding is easy
Suitable for high speed welding
Characteristics of pulsed MIG welding (GMAW):
The MIG method is mainly used for aluminum welding, and pulse control is usually used.
Pulsed MIG ensures minimal spatter at jet transition. The appearance of the welding seam is beautiful, and the shape of a flat welding seam can be obtained. Compared with non-pulsed MAG/MIG welding, since thicker wire can also realize jet transition, improved wire feeding performance and reduced wire cost can be realized when welding thin sheets. Especially when welding aluminum and alloys, it has advantages in automation and robotization.
Principle of pulsed MIG welding (GMAW): The welding current is periodically repeated as a pulsed current Ip and a base current Ib, and droplet transfer can be carried out in a wide range of welding current fields (see figure below).
3) Tungsten arc welding (TIG)
Arc welding in shielding gas with non-consumable electrode, TIG welding, eng. Tungsten Inert Gas (TIG for short), also known as Tungsten Arc Welding (GTAW for short)
The principle is this: TIG welding is a method of creating an arc between a tungsten electrode and a base metal in an inert gas such as argon, so that the base metal and the added welding material are melted and welded.
DC TIG welding
Using the DC arc welding power supply as the welding power source, the welding method with electrode as negative and base metal as positive is widely used in welding stainless steel, titanium, copper and copper alloys.
TIG AC welding
The welding power source is an AC arc welding power supply, and the positive and negative polarities of the electrodes and base metal are mutually reversed. When the electrode is positive (EP polarity), overheating of the electrode consumes a lot, and the oxide layer on the surface of the base metal can be removed, which is the so-called cleaning effect. Using this cleaning effect, it is widely used in the welding of aluminum and magnesium.
Features of TIG welding (GTAW):
Almost all industrial metals and alloys can be welded
Good welding quality and high reliability
The weld is well formed, no slag needs to be removed
No spatter
Low smoke and dust
Applicable to a wide range of thin and thick plates
4) RESISTANCE
Resistance welding is widely used in metal welding, such as arc welding, and has become an indispensable welding method in industries such as automobiles, household appliances, electronic equipment, railways, construction and civil engineering.
The principle is this: a welding method that melts and joins the base metal using resistance heat at the junction of the material to be welded, concentrating a large current and applying pressure. The basic principle of resistance welding is to use resistive heating to melt metal, pressurize and combine, including resistance spot welding, projection welding, seam welding, seam welding and so on.
Scheme of resistance spot welding
Resistance welding characteristics
High efficiency spot welding of two overlap joints and high welding speed,
Suitable for mass production
Beginners can also solder easily
Slight welding deformation
Free of welding wire, chemicals and consumables
Low cost
5) Plasma cutting (PLASMA)
Plasma cutting principle: the arc discharge is performed between the base material (including the nozzle in the torch) and the electrode in the torch, and the cutting method of the base material is cut by the discharge. thermal energy to force the compressed gas to generate a high-temperature, high-speed plasma arc. Small holes in the nozzle make the plasma flow thinner and denser.
Features of air plasma cutting:
Easily cuts all metals
High cutting speed
Less deformation when cutting, cutting can be done without a fixed fixture
Cut shape is unlimited
Small heat affected area
Contact and non-contact cutting available
Does not require special knowledge, easy to operate
Machine equipment is cheaper