Article Description : This article tilted ‘Welding Suppliers- Global Sourcing considerations’ explains the process and its types that a professional must know before he/ she decides to involve in supplier sourcing.
Metal welding is a joining process in which two or more pieces of metals are joined together by simultaneous heating and cooling operations, occasionally combined with pressing process.
1. Fusion welding
2. Solid State welding
The combining action of two metal pieces by applying heat, with or without the usage of filler metal is known as Fusion process.
A few examples of fusion process include Arc, oxy-fuel gas, resistance spot, etc.
Solid State :
The combining action of two metal pieces by applying heat/ pressure without addition of filler material and melting of base metals is known as Solid State process.
A few examples of solid-state process include Forge, friction welding and diffusion , etc.
The fusion process in which an electric arc produces the heat required to melt and join two or more metal pieces is known as Arc process. The electric arc generates heat between the electrode and the work metal.
The energy produced from the electric arc causes high temperatures. Usually fillers are added during the process to enhance the joint strength.
An Electric arc is a discharge of intense electric current across a gap between 2 electrodes in a circuit. In this gap of air/ vapor, the electric current ionizes the gases producing a plasma.
1. Consumable – During this process, the welding consumable i.e. the electrode gets melted away.
2. Non-consumable – The electrodes in this process do not melt away.
I. Consumable :
Weld rods and weld wires are common forms of welding supplies under consumable electrodes. During weld, the rods/ wires are melted and are used as filler material for the fusion process.
Shielded Metal Arc (SMAW), Gas Metal Arc Welding (GMAW) or Metal Inert Gas (MIG ), Flux cored arc welding (FCAW) and Electro gas Welding.
I. Shielded Metal Arc :
During this process, an arc is stroke between a flux coated metal electrode and the base metal. The flux coating is responsible for the formation of a shielding around molten metal. This process is otherwise known as Stick welding.
SMAW has a wide range of welding applications outdoor. It is used in welding joints in processes involving steel and cast iron.
II. GMAW or Metal Inert Gas (MIG) welding:
In this method, the electrode is a metal wire that is surrounded by gas as a shield. The spool feeds the wire consistently via a welding gun.
For aluminum, we use argon and helium as shielding gas. The combination of bare electrode and shielding gases, thereby prevent slag formation. This eliminates the requirement of manual clean-up of slag.
This process involves fusion of metal pieces by the heat produced by electric arc in the presence of inert or reactive gas/gas mixture supplied externally.
III. Flux cored arc welding:
It is a method in which a tubular electrode holds the flux with/without external shielding gas. Depending on the availability of the shielding gas, the process can be categorized as
1. Self-shielded/ No- shielding gas
2. Gas- shielded/ dual- shielded
IV. Electro Gas Welding:
This process involves the usage of self- shielded electrodes or shielding gas supplied from an external source. Self- shielded electrodes indicate a flux coating around the electrode that produces the necessary shielding gas required for the process. Contrastingly, the other type involves external shielding gases while a bare electrode wire is used.
Submerged arc :
In this process, a flux shields the arc and the molten metal. Into this flux is submerged the tip of the electrode that is fed by an automatic welding machine known as electrode feeding machine.
2. Vessel manufacture
3. Pressure &
4. Storage Tanks
5. Structural shapes
7. Fabrication of heavy steel plate
8. Large diameter pipes
This metal welding process does not involve the melting of electrode. Usually the electrodes used in this process is made of tungsten.
Gas tungsten arc, Plasma Arc, Carbon arc and Stud
I. Gas Tungsten Arc or TIG welding:
This process is otherwise known as Tungsten inert gas. The electrode used is made of tungsten and for arc shielding, inert gas is used.
1. This process is well known for fusion of metals made of dissimilar materials.
2. The major applications are Aluminium and Stainless-Steel products
II. Plasma Arc :
In this process, a nozzle holds the tungsten electrode and causes the inert gas in it to enter the arc to form intense plasma cutter arc steam. This is an extended process of Gas metal tungsten welding. The tungsten used in the process is usually non-consumable.
IV. Carbon Arc :
In this process, the electrode is made of Carbon (Graphite). If required, the process involves filler metal. Flux requirement for this process depends on the type of weld material.
The heat produced by this process is used for cast iron repair.
Used to deposit wear-resistance materials on work surface.
IV. Stud :
Stud is the fusion of a fastener or nut to another metal. The metal usually is a base and is large is size. Both parts are heated using electricity and can be made of dissimilar metals.
3. Welding underwater
4. Welding in dangerous or explosive zones
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