What Is a Welding Service?
A welding service is the process of joining two or more metal parts by applying pressure, heat, or both.
In general, metals begin to melt when they are subjected to external energy, such as pressure or heat. A welding service is a process in which metals are joined by this external energy and then cooled and adhered to each other.
Uses of Welding Services
Welding services are used to join metals of the same type or different metals. Specific applications are as follows:
- Automobile parts and machinery frames
- Workbenches
- Aircraft parts
- Ship bodies
- Electrical equipment
- Construction equipment
- Various bogies
- Rolling stock and car bodies
- Plant piping and boilers
As you can see, they are used in every field of industry. Other examples include metal furniture, office automation equipment, housing equipment, sports equipment, theater equipment, and park playground equipment.
Principles of Welding Services
Welding services can be broadly classified into three types: fusion welding, which joins in a molten state; pressure welding, which joins in a solid state; and brazing, which welds in a molten-solid state. The appropriate welding method is selected according to the intended use after joining.
1. Fusion Welding
Fusion welding is a method in which a portion of the metal to be joined is melted by heat, light energy, etc., and then cooled and solidified. Fusion welding includes arc welding, plasma welding, and laser welding. The feature of this method is that it is possible to process thicker plates and larger sizes. However, it has the disadvantage of production variation due to the tendency for distortion to occur in the joint.
2. Pressure Welding
In pressure welding, the joint is heated and melted by friction or gas combustion heat, and then mechanical force is applied to the joint. Pressure welding includes gas pressure welding, friction welding, resistance welding, diffusion welding, ultrasonic pressure welding, and explosion welding. The characteristics of pressure welding are that it can weld thin sheets of metal and production conditions can be easily controlled. However, it is not suitable for parts that require high joint strength.
3. Brazing
Brazing is a method of joining metals by heating a solder called “brazing filler,” which has a lower melting point than the metal to be joined, and allows it to penetrate between the surfaces to be joined. There are two types of brazing materials: hard brazing filler metal with a melting point of 450°C or higher and soft brazing filler metal with a melting point of less than 450°C. Soft brazing filler metal is used for electronic components.
Soft brazing is especially used in joining electronic components and connectors and is called soldering. It is characterized by its ability to join dissimilar metals and its advantage of not causing damage to the metal being joined since it does not melt the metal. However, it is not suitable for joining thicker metals because its strength cannot be maintained.
Types of Welding Services
Of the many welding methods, there are four typical welding services that are often used: arc welding, spot welding, laser welding, and brazing.
1. Arc Welding
Arc welding is the most commonly used method of fusion welding. When electrodes are placed at two points in the air and a high voltage is applied between them, at a certain voltage, the insulation of the air is broken and an electric current flows. At that time, a sharp light that draws an arc and high heat is generated at the same time. This method of welding utilizes this heat source. Arc welding can be further classified into several types.
Covered Arc Welding
Covered arc welding uses a welding rod made of the same material as the material to be welded as an electrode to generate an arc. The welding rod is coated with flux. Since this is mainly a manual welding process, it has the disadvantage that the skill of the welder tends to vary.
Semi-automatic Arc Welding
This is called semi-automatic arc welding because welding wire is supplied automatically and welding is done manually. Once the welder becomes accustomed to the welding process, it is relatively easy to weld. Semi-automatic welding uses an inert gas called shielding gas to protect the weld from oxygen in the air. Since the shielding gas is carried away by the wind, it is not suitable for outdoor welding.
There are flux wires that do not require shielding gas and can be welded outdoors. The center of the wire is filled with flux.
TIG Welding
TIG welding is welding using Tungsten inert gas. Tungsten, which does not wear out, is used for the discharge electrode, and argon gas or helium gas is used for the shielding gas.
There is no scattering of sparks, the arc is stable, and almost no spatter is produced. In addition to TIG welding, other types of arc welding using shielding gas include MIG (metal inert gas) welding and MAG (Metal Active Gas) welding.
MIG welding uses a consumable electrode for the discharge electrode. MAG welding is a type of arc welding that uses active gas (carbon dioxide or a mixture of argon and carbon dioxide) as the shielding gas and is also called carbon dioxide gas arc welding. It is not suitable for non-ferrous metals such as aluminum.
2. Resistance Spot Welding
Resistance spot welding is a method of welding by passing an electric current across the weld area and using joule heat due to electrical resistance. It is used for joining lids of lithium-ion batteries.
3. Laser Welding
Laser welding is a welding method that uses a high-energy-density laser beam as a heat source. It is faster than other welding methods and produces less distortion. There are two types of lasers used for laser welding: gaseous and solid-state lasers. Gaseous lasers use a gas, such as carbon dioxide, to extract light. Solid-state lasers include YAG lasers, fiber lasers, and semiconductor lasers.
4. Brazing
Brazing is suitable for the precision joining of electronic components and thin sheets because it does not damage the original metal. Therefore, it can be used to join dissimilar metals and simultaneously join a wide variety of electronic components and is also suitable for automated production.