- TIG welding is typically performed manually, with one hand holding the welding gun and the other holding the welding wire. It is ideal for small-scale operations and repairs.
- MIG and MAG welding use an automatic wire feed mechanism, which allows automatic welding, but manual welding can also be performed.
- The main difference between MIG and MAG welding lies in the protective atmosphere used during the welding process. MIG welding typically uses argon for shielding and is suitable for welding non-ferrous metals, while MAG welding uses a mixture of argon and carbon dioxide and is ideal for welding high-strength steel and high-alloy steel.
- TIG and MIG welding are classified as inert gas shielded welding, also known as argon arc welding. The shielding gas normally used is argon, as it is cheap, although helium can also be used. The process is commonly referred to as argon arc welding.
Tungsten inert gas (TIG) welding uses tungsten or tungsten alloy as the electrode material and protects the base metal and filler wire with an inert gas while melting them through the arc generated between the electrode and the base metal (workpiece). work). It is also known as Gas Tungsten Arc Welding (GTAW) or Tungsten Inert Gas Welding (TIG).
Manual arc welding (STICK)
Shielded arc welding (SMAW) is a welding process that uses an electric arc to melt the coated electrode and base metal. The coated electrode is covered by a welding flux that melts when heated, providing several functions such as arc stabilization, slag formation and weld deoxidation and refinement.
Schematic diagram of manual arc welding with electrodes
The welding power source used for shielded arc welding (SMAW) must be an AC welding machine or a DC arc welding machine with step-down characteristics.
Typically, an AC arc welding machine is used, but when more arc stability is required, a DC arc welding machine can be used.
The main characteristics of Shielded Arc Welding (SMAW) are:
- Simple welding operation
- Lightweight, easy-to-move welding tongs
- Wide range of applicability in operations.
GMAW（CO 2 /MAG/MIG）
What is GMAW?
Gas Metal Arc Welding（GMAW）
What is MAG welding?
Active Gas Welding of Metal (Active Gas)
What is MIG welding?
Metal inert gas welding (inert gas)
GMAW classification
Gas metal arc welding (GMAW) is typically divided into two types based on the type of shielding gas used: MAG welding and MIG welding.
MAG welding uses CO 2 or a mixture of CO 2 and argon or oxygen (these are called active gases). When only CO 2 is used, it is referred to as CO 2 arc welding, which is different from MIG welding.
In contrast, MIG welding uses inert gases, such as argon or helium, as a shielding gas.
GMAW Principle
The principle of gas metal arc welding (GMAW) is to generate an arc between the fine diameter consumable electrode (welding wire) and the base metal, while sealing the environment with shielding gas and melting the base metal and wire of welding.
GMAW is widely used in various welding methods, including semi-automatic welding with manual welding gun, robotic welding and automatic welding.
Schematic diagram of gas shielded consumable electrode welding
GMAW Features
The characteristics of CO 2 welding are:
- Fast welding speed
- High arc efficiency
- Deep molten pool depth
- High deposition efficiency
- Versatility in the use of welding wire for different sheet thicknesses
- Good welding quality with minimal post-welding deformation
- Flexibility in using welding wire for a variety of basic materials.
Features of MAG welding:
In addition to the advantages of CO2 welding, it also has a clean and attractive weld bead, low spatter levels, ease of double-sided formation welding and full penetration welding, and is ideal for high-speed welding.
Characteristics of pulsed MIG welding (GMAW):
The MIG method is commonly used for welding aluminum and often employs pulse control. Pulse MIG welding can achieve minimal spatter through its spray transfer process. This results in a visually appealing weld and a flat weld height shape.
Compared with pulseless MAG/MIG welding, pulsed MIG welding can also use thicker wire to achieve spray transfer, improving wire feeding performance and reducing wire cost for thin plate welding.
In particular, MIG welding presents advantages in automation and robotization in the welding of aluminum and alloys.
Principle of pulsed MIG welding (GMAW):
In pulsed MIG welding, the welding current periodically alternates between a pulsed current (Ip) and a base current (Ib). This periodic alternation allows droplet transfer across a wide range of welding current levels (as shown in the figure).
TIG welding
What is TIG welding?
Tungsten inert gas (TIG) welding, also known as gas tungsten arc welding (GTAW), is a type of gas shielded arc welding with a meltless electrode. It is characterized by the lack of sputtering and the ability to weld stainless steel, aluminum, iron and other metals.
A non-consumable tungsten electrode is used and the weld is protected by an inert gas such as argon or helium. The arc is generated within the inert gas and the base metal is melted by the heat of the arc for welding.
Due to the stability of the arc and the protection provided by the surrounding inert gas, there is minimal spray during TIG welding. Although filler material can be used, it is not necessary for the welding process.
- A. Shielding gas
- B. Tungsten electrode
- C. Argon
- D. Arco
- E. Metal welding
- F. Melt pool
- G. Welding Rod
Semi-automatic equipment for tungsten inert gas (TIG) welding consists of a welding power source, a welding torch, a liquefied gas cylinder, a gas flow regulator and any necessary additional equipment such as a welding torch water-cooled or wire welding materials.
It is important to highlight that the polarity of the current (positive or negative) must be selected based on the base metal, therefore the welding source must be equipped with a device that allows this selection.
- A. Liquefied gas cylinder
- B. Welding power source
- C. Remote control box
- D. Welding torch
TIG welding principle:
Tungsten inert gas (TIG) welding is a welding method that involves melting and welding the base metal and any added filler material, creating an arc between the tungsten electrode and the base metal in an environment protected by a gas inert like argon.
TIG welding type
There are several variations of tungsten inert gas (TIG) welding, which can be distinguished based on AC/DC rating, pulse, and welding wire.
DC TIG welding uses a DC arc welding power source and typically employs a negative electrode and positive base metal for welding stainless steel, titanium, copper and copper alloys.
AC TIG welding, on the other hand, uses an AC arc welding power source and alternates the positive and negative polarities of the electrode and base metal. When the electrode is positive (EP polarity), it experiences significant overheating and is consumed quickly, resulting in a cleaning effect that removes the oxide layer from the surface of the base metal. This cleaning effect is widely used in welding aluminum, magnesium and other metals.
The choice between AC or DC for tungsten inert gas (TIG) welding should be based on the type of base metal. Another variation of TIG welding is called “pulse TIG welding,” which alternates the welding current between pulse current and base current on a periodic basis.
During the use of pulsed current, the base metal is melted, and during the use of base current, it is cooled. This periodic alternation allows the formation of melting points and bead-like welds.
| Classification according to the output current waveform | ||
|---|---|---|
| Output current | Pulse | Frequency |
| CC | with | Low frequency (0.5 Hz to 20 Hz) |
| with | Medium frequency (20 Hz to 500 Hz) | |
| with | High frequency (above 20KHz) | |
| without | / | |
| B.C | with | Low frequency (0.5 Hz to 20 Hz) |
| with | Medium frequency (20 Hz to 500 Hz) | |
| without | / | |
When using welding wire in tungsten inert gas (TIG) welding, it can be divided into “cold welding wire method” and “hot welding wire method”.
The cold wire welding method uses conventional welding materials. In contrast, the hot wire method heats the welding wire by applying current in advance, which results in a higher deposition rate per unit time. The hot wire method can deposit three times the amount of welding material compared to the cold wire method, making it useful for quick welding in a short amount of time.
Although TIG welding provides high-quality welds, it can be time-consuming to achieve the required amount of deposition. The hot wire method helps overcome this limitation.
| Classification according to the presence or absence of welding wires | |
|---|---|
| Welding Stick | Welding wire mode |
| Without | / |
| With | Cold welding wire method |
| Hot wire method | |
The characteristics of tungsten inert gas (TIG) welding, also known as gas tungsten arc welding (GTAW), include:
- The ability to weld almost all industrial metals and alloys
- Reliable, high-quality welding
- A well-formed weld without the need for slag removal
- Minimal splashes
- Low levels of smoke and dust
- Versatility in application for both thin and thick sheets.
MIG welding
Metal Inert Gas (MIG) welding is a type of electric arc welding that uses an inert gas as protection, similar to Tungsten Inert Gas (TIG) welding. However, MIG welding is a welding method with a consumable electrode that melts the discharge electrode.
It is commonly used for welding stainless steel and aluminum alloys and the shielding gas may vary depending on the welding material. The electrode is made of iron wire and is supplied in the form of a coil, which is installed in a welding wire feeding device.
The electric motor drives a transfer roller to automatically feed the welding wire to the top of the welding torch. The welding wire is energized when it passes through a contact strip. An arc is generated between the welding wire and the base metal, allowing welding while melting the welding wire and base metal. At the same time, shielding gas is supplied around the welding area through a nozzle to isolate the arc and molten materials from the atmosphere.
- A. Air or Ar+2% O 2 gas
- B. Solid wire electrode
Semi-automatic Metal Inert Gas (MIG) welding equipment consists of a welding power source, a welding wire feeding device, a welding torch and a liquefied gas cylinder.
As MIG welding is mainly used for aluminum welding, the welding wire supply device is equipped with a design that can supply soft aluminum wire stably (in 4-axis mode).
- A. Liquefied gas cylinder
- B. Gas flow regulator
- C. Welding power source
- D. Welding wire feeding device
- E. Remote control box
- F. Welding torch
MIG welding classification
Metal Active Gas (MAG) welding can be classified based on the type of shielding gas and welding wire used.
Metal Inert Gas (MIG) welding can also be classified into AC/DC types and whether it is pulsed welding.
| MIG welding classification | ||
|---|---|---|
| CC | Without | MIG welding with short circuit arc |
| Without | Spray MIG welding | |
| Without | High current MIG welding | |
| With | M1G pulse welding | |
| With | Low Frequency Superimposed Pulse MIG Method | |
|
B.C |
With | AC pulse MIG welding |
| With | Low Frequency Superimposed AC Pulse M1G Welding | |
| DC+AC | With | AC/DC composite pulse MIG welding |
AC/DC composite pulse MIG welding
Metallic inert gas (MIG) short-circuit arc welding is a welding method that uses the phenomenon of short-circuit transfer. This method is ideal for welding thin sheet materials, as it uses semi-automatic welding and generates less heat transfer to the base metal.
Short-circuit arc Metal Active Gas (MAG) welding is commonly used to weld medium-thickness plates with complex structures, while pulse MIG welding is typically used to weld medium-thickness plates with MIG welding.
Spray MIG welding
Spray Metal Inert Gas (MIG) welding is a welding method that sets the welding current above the critical current and increases the arc voltage. This method uses the spray transfer phenomenon to melt and atomize the welding material for bonding.
When welding aluminum without spatter, defects such as poor fusion may occur. In this case, the arc voltage can be slightly reduced and welding can be carried out in a small spray transfer state. However, with the popularity of pulsed MIG welding, which can handle welding from thin plates to medium thickness plates, the use of spray MIG welding has become less common.
The high-current Metal Inert Gas (MIG) welding method uses a thick diameter welding wire (with a diameter of approximately 3.2 mm to 5.6 mm) for welding. The welding device consists of a welding torch with double shielding gas nozzles and a power supply with stable current characteristics and rated output current of about 1000 A.
Traditional pulsed MIG welding
The direct current (DC) and pulsed metal inert gas (MIG) welding method is also known as the traditional pulse MIG welding method. The basic principle is the same as Metal Active Gas (MAG) pulsed welding. It is a welding method that alternates between a small base current of the maintained arc and a pulsed current above the critical current to ensure that the welding wire can be atomized even when the average current is lower than the critical current. This method can efficiently and effectively weld plates, including thin and thick plates.
Low Frequency Superimposed Pulse Welding
The low-frequency superimposed pulse welding method is a development of inert metal pulse (MIG) welding for welding high-value aluminum. It is used to produce a beautiful fish scale weld and is often used to weld thin aluminum plates in automobiles and motorcycles.
