Arc Welding

One of the most fundamental principles involved in the arc welding process is that a solid metal electrode is connected to the electrical power supply to curate a closed-circuit once the electrode touches the plate. Suppose a professional raises the electrode a few millimetres above the plate.

In that case, the current will jump the gap and create a high-temperature electrical arc without the risk of weld distortion. Such arc results in the ability to melt the parent metal and inside the electrode, ensuring both metals sufficiently fuse. 

An essential part of the arc welding process is the arc shielding aspect, which is most notably helpful in preventing the fused metal from becoming oxidised with slag inclusions.

Arc shield protects it from constant contact with water vapour, oxygen and dangerous gases that the welding equipment emits. Two of the most frequently used shielding techniques that shipyards include: Slag Shielded Arc Welding and Inert Gas Shielded Arc Welding,

Gas Welding

Gas shielded arc welding standard procedures tend to use a blanket of inert gas compared to a flux, and this gas helps to provide adequate insulation for the arc from the encompassing atmosphere. It's extensively utilised for welding shipyards, especially the lighter structures.

Tungsten Inert Gas Welding (TIG):

In the TIG Welding process, engineers and welders will utilise arcs made to slot between the parent metal plates and non-consumable tungsten electrodes. A nozzle surrounds the tungsten electrode allowing it to maintain continuous inert gas flow around the arc. The arc is shielded from oxygen due to the inert gas, stabilising it and reducing the possibility of oxidation in the weld pool.

Introduced to the arc is a filler rod or weld bead, which ultimately helps fuse the metals. Argon is the inert gas often utilised in the TIG welding process, so inhalation of this chemical is hazardous, resulting in dizziness, nausea, loss of consciousness and worse. Welding of this kind is usually preferred for constructing welded plates with a thickness of around 6-8mm.

Metal Inert Gas Welding (MIG):

MIG Welding (Metal Inert Gas) is often considered an advancement on the TIG Welding (Tungsten Inert Gas) technique, which is the instance where electrodes are in the form of a consumable metal wire. The welding torch is connected to the power supply through electrode wires, which is an electrical contact tube allowing the wires to gain heat for welding use.

Using a pair of driver rollers, engineers will feed the electrode wire into its nozzle, wherein the current will pass through the tube at a tremendous pace. A separate line maintains a consistent inert gas flow in the welding torch, creating a thorough blanket of gas around its stabilised arc.

One of the most widely used inert gases for the purpose of welding is carbon dioxide; it emits from the welding tools and surrounds the atmosphere. MIG welding is frequently used for welding deckhouses, overhead deck plates and spherical membrane tank units in gas carriers made of aluminium. 

Resistance Welding

The joining of two metals defines resistance welding through a passing current and applying immense pressure. Such happens for a duration as the current makes its way through the metal area to be joined; its heat allows the metal to join together, creating a tight bond. One of the most significant aspects of resistance is that, unlike other welding devices, it requires no other devices or materials to create its bond, making it incredibly cost-effective.

There are numerous different resistance welding forms that all engineers and sheet metal fabricators will be familiar with, including upset, projection, flash and spot and seam welding. Each of these welding methods and techniques differs as they use a range of shapes and types of weld electrodes to apply pressure and conduct the current to an adequate level.

Copper-based alloys are typically used to manufacture the electrodes used in this process because they have excellent conductive properties, unlike other metal materials. They can be successfully cooled by water flowing throughout the electrodes cavities and the resistance welding machines' other conductive tooling parts.

Resistance welding machines have been skilfully designed and built over the years to suit a broad range of applications, including aerospace, automotive and industrial environments. Their uses are only expanding as ideas for the ship's design evolve. Automated welding allows for plenty of these machines to be repeatable and highly controlled, so manufacturers can ensure that staff production is constant and that productivity levels are high for a realistic shop setting.