1. TIG welding is generally a manual welding with one hand holding the welding gun and the other hand holding the welding wire, which is suitable for small-scale operation and repair.
2. MIG and MAG, the welding wire is sent from the welding gun through the automatic wire feeding mechanism, which is suitable for automatic welding, and of course, manual welding can also be used.
3. The difference between MIG and MAG is mainly in the protective atmosphere.
The equipment is similar, but the former is generally protected by argon, which is suitable for welding nonferrous metals;
The latter is generally mixed with carbon dioxide active gas in argon, which is suitable for welding high-strength steel and high alloy steel.
4. TIG and MIG are inert gas shielded welding, commonly known as argon arc welding.
Inert gas can be argon or helium, but argon is cheap, so it is commonly used. Therefore, inert gas arc welding is generally called argon arc welding.
Tungsten inert gas shielded welding is a welding process in which tungsten or tungsten alloy is used as electrode material, and under the protection of inert gas, the base metal and filler wire are melted by the arc generated between the electrode and the base metal (workpiece).
It is called GTAW in English – Gas Tungsten Arc Welding or TIG——Tungsten Inert Gas Welding.
Manual arc welding (STICK)
English name: Shielded Arc Welding (abbreviation:SMAW).
The principle is to produce an electric arc between the coated electrode and the base metal, and use the arc heat to melt the electrode and the base metal.
The outer layer of the electrode is covered with welding flux, which melts when heated, and has the functions of stabilizing the arc, forming slag, deoxidizing, refining, etc.
Schematic diagram of manual arc welding with electrodes
The AC welding machine or DC arc welding machine with descending characteristics shall be used as the welding power source.
Generally, AC arc welding machine is used, and DC arc welding machine is used when arc stability is especially required.
- Simple welding operation;
- Welding tongs are light and easy to move;
- Applicable to a wide range of operations.
What is GMAW?
Gas metal Arc Welding（GMAW）
What is MAG welding?
Metal Active Gas Welding (Active Gas)
What is MIG welding?
Metal Inert Gas Welding (Inert Gas)
GMAW is generally divided into MAG welding and MIG welding according to the type of shielding gas.
MAG welding uses CO2 or mixes CO2 or oxygen in argon (these are called active gases).
The welding habit of only using CO2 gas is called CO2 arc welding, which is different from MIG welding.
Inert gases such as argon and helium are used for MIG welding.
Its principle is: a welding method that generates an arc between the thin diameter consuming electrode (welding wire) and the base metal, seals the surroundings with shielding gas, and melts the base metal and welding wire.
It is widely used in semi-automatic welding with hand-held welding gun, robot welding and automatic welding.
Schematic diagram of consumable electrode gas shielded welding
Features of CO2 welding:
- Fast welding speed;
- High arc striking efficiency;
- Depth of molten pool;
- High deposition efficiency;
- One welding wire can be used for various plate thicknesses;
- Good welding quality, small deformation after welding;
- One welding wire can be used for a variety of base materials.
Characteristics of MAG welding:
In addition to the advantages of CO2 welding, the weld seam has beautiful appearance, less spatter, easy double-sided forming welding and all-round welding, and is suitable for high-speed welding.
Characteristics of pulsed MIG (GMAW) welding:
MIG method is mostly used for aluminum welding, and pulse control is generally adopted.
Pulse MIG welding can achieve minimal spatter through jet transfer.
The weld appearance is beautiful, and the flat weld height shape can be obtained.
Compared with non pulse MAG/MIG welding, the thicker wire can also realize the jet transfer, so the wire feeding performance can be improved and the wire cost can be reduced in the thin plate welding.
Especially in aluminum and alloy welding, it has advantages in automation and roboticization.
Principle of pulsed MIG (GMAW) welding:
The welding current is repeated periodically in the form of pulse current Ip and basic current Ib, which can realize droplet transfer in a wide range of welding current fields (see fig.).
What is TIG welding?
Non melting electrode gas shielded arc welding, TIG welding, English is Tungsten Inert Gas (abbreviated as TIG), also known as Gas Tungsten Arc Welding (abbreviated as GTAW).
This is a kind of arc welding that does not splash sparks and supports welding of stainless steel, aluminum, iron and other metals.
Tungsten that will not be consumed as discharge electrode is used, and inert gases such as argon and helium are used as shielding gas.
Arc is generated in inert gas, and the base metal is melted by arc heat for welding.
Although welding materials are also used, the arc is also very stable due to the inert gas surrounding the welding part, and there is almost no sputtering.
- A. Shielding gas
- B. Tungsten electrode
- C. Argon
- D. Arc
- E. Welding metal
- F. Molten pool
- G. Welding rod
The semi-automatic equipment for TIG welding is composed of welding power supply, welding torch, liquefied gas cylinder, gas flow regulator, etc.
When water-cooled welding torch or wire welding materials are used, different necessary equipment shall be added.
In addition, since it is necessary to select the polarity of the current (positive/negative) according to the base metal, the welding power source must be equipped with a device that can select the polarity according to the base metal.
- A. Liquefied gas cylinder
- B. Welding power source
- C. Remote control box
- D. Welding torch
TIG welding principle:
TIG welding is a method of melting and welding the base metal and added welding materials by generating an arc between the tungsten electrode and the base metal in an inert gas environment such as argon.
Type of TIG welding
There are many types of TIG welding, and different types can be distinguished according to AC/DC classification, pulse and welding wire.
DC TIG welding:
The DC arc welding power source is used as the welding power source, and the welding method with negative electrode and positive base metal is widely used for welding stainless steel, titanium, copper and copper alloys.
AC TIG welding:
With AC arc welding power source as the welding power source, the positive and negative polarities of electrode and base metal change with each other.
When the electrode is positive (EP polarity), the overheating consumption of the electrode is large, and the oxide layer on the surface of the base metal can be removed, which is called the cleaning effect.
The cleaning effect is widely used in aluminum, magnesium and other welding.
Select AC/DC according to the type of base metal. Pulse welding is called “pulse TIG welding”.
In pulse TIG welding, the welding current will be changed into pulse current and basic current in a certain period.
The base metal is melted during the use of pulse current and cooled during the use of base current.
The method can periodically form melting points and bead like welds.
|Classification according to output current waveform|
|DC||with||Low frequency (0.5Hz to 20Hz)|
|with||Medium frequency (20Hz to 500Hz)|
|with||High frequency (above 20KHz)|
|AC||with||Low frequency (0.5Hz to 20Hz)|
|with||Medium frequency (20Hz to 500Hz)|
When using welding wire, it can be divided into “cold welding wire method” and “hot welding wire method”.
The cold welding wire method is a method using conventional welding materials.
The hot wire method is to release current to the welding wire in advance and heat the welding wire, which can increase the deposition amount per unit time.
The hot wire method can deposit about 3 times of the welding materials of the cold wire method to achieve rapid welding in a short time.
Although TIG welding can achieve high-quality welding, it takes a long time to obtain the amount of welding materials necessary for deposition.
The hot wire rule can make up for this shortcoming.
|Classification according to the presence or absence of welding wires|
|Welding stick||Welding wire mode|
|With||Cold welding wire method|
|Hot wire method|
Characteristics of TIG (GTAW) welding:
- Can weld almost all industrial metals and alloys;
- Good welding quality and high reliability.
- The welding is well formed without removing the slag;
- No splash;
- Less smoke and dust;
- Can be widely applied to thin and thick plates.
“MIG (Metal Inert Gas) welding” belongs to electric arc welding, and inert gas will be used as shielding gas as TIG welding, but MIG welding is an electrode consumption welding method of melting discharge electrode.
It is usually used for the joint of stainless steel and aluminum alloy, and the shielding gas can be distinguished according to the welding materials.
The electrode is made of iron wire.
The welding wire will be rolled into a coil and installed in the welding wire supply device.
The electric motor will drive the transfer roller to automatically transfer the welding wire to the top of the welding torch.
The operation of energizing the welding wire will be carried out when the contact strip passes through.
The arc generated between the welding wire and the base metal can be used for welding while melting the welding wire and the base metal.
At this time, the equipment will supply shielding gas around the welding part through the nozzle to isolate the arc and molten materials from the atmosphere.
- A. Ar or Ar+2% O2 gas
- B. Solid wire electrode
The semi-automatic equipment for MIG welding is composed of welding power supply, welding wire supply device, welding torch and liquefied gas cylinder.
As MIG welding is mostly used for aluminum welding, the wire supply device is added with a design that can stably supply soft aluminum wire (4-axis mode).
- A. Liquefied gas cylinder
- B. Gas flow regulator
- C. Welding power source
- D. Welding wire supply device
- E. Remote control box
- F. Welding torch
Classification of MIG welding
MAG welding can be classified according to the type of shielding gas and welding wire.
MIG welding can also be classified according to the AC/DC type and whether there is pulse.
|Classification of MIG welding|
|DC||Without||Short circuit arc MIG welding|
|Without||Spray MIG welding|
|Without||High current MIG welding|
|With||Pulse M1G welding|
|With||Low frequency overlapping pulse MIG method|
|With||AC pulse MIG welding|
|With||Low frequency overlapping AC pulse M1G welding|
|DC+AC||With||AC/DC Composite Pulse MIG Welding|
AC/DC Composite Pulse MIG Welding
“Short circuit arc MIG welding” is a welding method that uses the phenomenon of short circuit transfer (short circuit arc).
As semi-automatic welding is more and the heat transferred to the base metal is lower, it is suitable for thin plate materials.
Short circuit arc welding of MAG welding is commonly used for welding medium thick plates with complex structures, while pulse MIG welding is commonly used for welding medium thick plates with MIG welding.
Spray MIG welding
Spray MIG welding is a welding method that sets the welding current above the critical current and increases the arc voltage.
MIG welding method using the “spray transfer phenomenon” of melting and atomization of welding materials for bonding.
Welding defects such as poor fusion may occur if aluminum is welded without sputtering.
At this time, the arc voltage can be slightly reduced and the welding can be carried out in a small spray transition state.
However, since the “pulse MIG welding method” which can cover the welding of thin plates to medium thick plates has been popularized, the spray MIG welding method has been less commonly used.
The “high current MIG welding method” uses a welding wire with a coarse diameter (about 3.2 mm to 5.6 mm in diameter) for welding.
Welding torch with double shielding gas nozzle and power supply with stable current characteristics with rated output current of about 1000 A are adopted for the welding device.
Traditional pulse MIG welding
The “DC” and “pulse” MIG welding method is also known as the “traditional pulse MIG welding method”.
The basic principle is the same as that of pulse MAG welding.
It is a welding method that the basic small current of the maintained arc and the pulse current above the critical current are output alternately to ensure that when the average current is lower than the critical current, the droplet transfer of the welding wire can also be atomized.
It can weld plates including thin plates and thick plates with high efficiency and quality.
Low frequency overlapping pulse welding
“Low frequency overlapping pulse welding method” is developed based on pulse MIG welding for the purpose of high added value welding of aluminum.
Because the beautiful fish scale weld can be obtained, it is often used for welding thin aluminum plates on automobiles and motorcycles.