When we say the word “fusion” we mean the process of applying pressure to 2 distinct pieces of metal to the point that they are one thing. Basically, fusion welding occurs when you weld metals of the same make and same melting points. Fusion welding doesn’t always require the use of filler material either.
Where is fusion welding used?
Usually, fusion welding is done in construction areas on bolts and rivets. When you fusion weld you are heating the pieces of metal until it’s molten and then you allow them to cool until they solidify. Fusion welding can be separated / categorized by it’s being a consumable or non – consumable electrode method.
What are fusion welding processes?
There are a few fusion welding processed. They can all be categorized according the levels of heat they use (and whether they’re consumable or non-consumable electrode processes) such as:
- Electric Arc
- Gas
- Electrical Resistance
- High Energy Density
What are the arc welding processes?
Arc welding is a welding process that’ used to create a bond between 2 metals. Arc welding occurs when an electric arc from either a DC or AC power supply creates an intense heat of around 6500 degrees Fahrenheit. Below are the Arc welding processes.
Shielded Metal Arc Welding
What is Shielded Metal Arc Welding?
Shielded Metal Arc Welding is also known as manual metal arc welding, stick welding, or flux shielded arc welding. It’s suitable for welding both non-ferrous and ferrous metals in all positions. However, it’s typically used to weld materials such as Iron and Steel for maintenance and repair industries and construction of heavy steel structures. SMAW electrodes are made up of a stick or a solid metal rod surrounded by compounds and metal powders with bonding agents that help bind the metals to the surface.
SMAW is one of the most popular (and earliest) welding processes because of it’s versatility and simplicity.
Video credits to Weldnotes.com. It goes over what Shielded Metal Arc Welding is.
Metal Inert Gas Welding and Metal Active Gas Welding
What is Metal Inert Gas Welding?
Metal Inert Gas Welding is a welding process where a solid wire electrode is fed through a welding gun directly into a weld pool to join two base metals together. Shielding gasses are then used to protect the weld pool from environmental contaminants such as oxygen.
MIG welding allows everyday people such as artists, hobby welders, farmers, ranchers, motor-sports enthusiasts, and DIY welders to perform welds on metals up to 1/2 inches thick.
Tungsten Inert Gas Welding
What is Tungsten Inert Gas Welding?
Tungsten Inert Gas welding (aka Gas Tungsten Arc Welding) is a welding process that uses a non-consumable electrode (made of tungsten) to deliver the current to the arc. Both the electrode and weld puddle are protected / cooled with an Argon shielding gas (usually). TIG welding also uses a filler material for reinforcement.
Video credits to Weldnotes.com. It goes over what TIG welding is.
Plasma Arc Welding
What is Plasma Arc Welding?
Plasma Arc Welding is a process similar to TIG welding. The electric arc in PAW is formed between an electrode (typically made of sintered tungsten) and the metals being worked on. In Plasma Arc Welding the plasma arc can be separated from the shielding gas envelope. The plasma is then forced through a fine bore copper nozzle, constricting the arc, and the plasma exits the orifice at velocities that approach the speed of sound.
Video credits to Skill Lync. This video explains what Plasma Arc Welding is.
Submerged Arc Welding
What is Submerged Arc Welding?
Submerged arc welding is a welding process that requires a metal core electrode. Both the weld (which is molten by this point) and arc zone are protected from contaminants by being submerged under a blanket granular fusible flux made of manganese oxide, lime, silica, and calcium fluoride. When the flux is molten it becomes conductive and provides a path between the work and the electrode. The thick layer of flux covers the molten metal which prevents spatter and sparks while also suppressing the intense UV radiation and fumes that are an integral part of the SAW process.
Video credits to xAZEZELx13. This video explains what Submerged Arc Welding is.
Flux Core Arc Welding
What is Flux Core Arc Welding?
Flux cored arc welding is a semi-auto welding process that uses a continuously fed consumable electrode which contains a flux and constant voltage (or constant current welding power supply). Externally supplied shielding gasses are used occasionally but more often than not the flux is relied upon to generate a shield from the atmosphere, which produces both gaseous protection and liquid slag protection for the weld.
fun fact: because of it’s high welding speed and portability flux-cored arc welding is often used in construction.
Video credits to Weldnotes.com. It goes over what Flux Core Arc Welding is.
What are the gas welding processes?
Gas welding is a welding process that uses gases and oxygen to weld metals together. There are a few names for gas welding but the most common are oxy welding and oxyacetylene welding. Types of gas welding processes are:
Oxy-Gasoline Welding
When fabrication costs are an issue pressurized gasoline is used a welding fuel. Gasoline torches are sometimes considered more effective for torch-cutting thick steel plates.
Oxy-Acetylene Welding
What is Oxy-Acetylene Welding?
Oxy-Acetylene welding uses a mixture of acetylene gas and oxygen gas to feed the welding torch. Oxy-Acetylene welding is actually considered the most common gas welding technique. The mixture of oxygen and acetylene gasses is known to produce the highest temperature of the available fuel gasses (it’s also one of the most expensive fuel gasses).
Video Credits to We Build Stuff. It’s an intro to Oxy-Acetylene Welding.
MAPP Gas Welding
What is MAPP Gas Welding?
MAPP Gas Welding (or Methylacetylene-propadiene-petroleum) is a gas mixture that’s considered more inert than other typical gas mixtures. This also coincidentally makes it safer for recreational or hobby welders to use.
Video credits to CNC TopNet. It gives an example of MAPP Gas Welding.
Butane / Propane Welding
What is Butane / Propane Welding?
Butane and Propane can be used both separately and together as fuel gasses. Both butane and propane have a lower flame temperature than acetylene but are also less expensive and easier to transport than acetylene.
Propane torches, when used by themselves, behave a bit differently than Butane. Propane torches are also used for bending, soldering, and heating. They also require a different type of torch tip because propane is a heavier gas.
Video credits to my tech trials. It discusses Butane torch brazing, soldering, and welding.
Hydrogen Welding
What is Hydrogen Welding?
Hydrogen gas welding is a welding process that generates welding heat by passing hydrogen through an electric arc that’s between two inclined electrodes. Hydrogen welding can be done at higher pressures than other fuel gas welding processes, which makes it better-suited for underwater welding. The heat produced during hydrogen welding is considered to be enough to efficiently weld Tungsten (3,422 degrees Celsius), which is the most refractory metal.
The hydrogen also acts as a shielding gas which prevents both oxidation and contamination from nitrogen, carbon, and oxygen. It also takes away the need of a flux for environmental shielding.
Video credits to Habibur Rahman. It discusses hydrogen welding.
What are the Electrical Resistance welding methods?
Electric Resistance Welding is a term used to group a number of welding processes that produce coalescence of faying surfaces where the heat to form the weld is generated via the electrical resistance of the materials and the time and force that’s used to hold both materials together while welding taking place. Factors that influence the heat / welding temperatures are:
- Metal coating or lack thereof
- Electrode materials
- Electrode geometry
- Electrode pressing force
- Electrode current
- Length of welding time
During electrical resistance welding small pools of molten metal are formed at the point of most electrical resistance and the same time an electrical current is passed through the metal.
Spot Welding
What is Spot Welding?
Spot welding is a form of resistance welding where two or more sheets of metal are welded together without using any filler metal. The welding process requires the use of pressure and heat to the weld area using shaped alloy copper electrodes which convey an electrical current through the weld pieces. As the material melts the parts are fused together. At this point the current is turned off and pressure from the electrodes is maintained and the joint is formed.
The heat used in spot welding is generated via an electric current which is transferred to work pieces via copper alloy electrodes. Copper is then used for the electrode as it has a high thermal conductivity and low electrical resistance compared to other metals. This ensures that the heat generated is generated in the work pieces rather than the electrodes.
The amount of heat generated depends entirely on the electrical resistance and thermal conductivity of the metal (and the time the current is applied). The equation used to express the level of heat generated is:
Q: Heat Energy
I: Current
R: Electrical Resistance
T: The time the current is applied
Video credits to Jeffrey Santo. It discusses basic spot welding.
Seam Welding
What is Seam Welding?
Seam Welding (aka Resistance Seam Welding) is a type of spot welding that uses motor driven wheels rather than stationary rods. Seam welding is est used for sheet metal fabrication since it passes an electrical current through the sheets of metal to be joined while they’re being held together via a mechanical force in a lap configuration between shaped copper electrodes. Fusion of the two metals occurs where the sheet metal surfaces touch one another – this is the point of highest electrical resistance as well as the point where the heat generation is highest.
Heat from the disc shaped electrode wheels create a continuous weld as the sheet metal is passed between them. This results in a non-hermetic seam weld or rolling resistance weld.
What is Consumable Wire Resistance Seam Welding?
Another form of seam welding is the consumable wire resistance seam weld. The difference between this and regular seam welding is that the electrode wheel is grooved so that a shaped copper wire can be placed between the material you’re trying to join and the wheel. Copper wire is then fed from a spool and passed around the electrode wheel at welding speed before it’s discharged into a scrap container. This makes sure the clean, uncontaminated surface is presented to the work.
Consumable Wire Resistance Seam Welding is highly reliable and achieves welding speeds of well over 70 meters per minute.
Video credits to Poor Man Mods. It shows how to seam weld.
Low-Frequency Electric Resistance Welding
What is Low-Frequency Electric Resistance Welding?
A Low-Frequency Electric Resistance Welded pipe is one that’s manufactured via cold-forming a sheet of steel in a cylindrical shape. The electrical current is passed between 2 edges of steel to heat the steel to a point where the edges are forced to form a bond between one another without using filler material. This welding process has become antiquated however and has been replaced by high frequency electric welding process.
Video credits to Rishika Janaki. It gives fun facts about low-frequency resistance welding.
Flash Welding
What is Flash Welding?
Flash Welding is a type of resistance welding process that doesn’t use any sort of filler metal. Pieces of metal are set apart at a distance based on their composition, thickness, and the desired properties of the weld once finished. A current is applied to the metal, and the gap between both metals creates resistance and subsequently creates an arc (which is required to melt both metals). Once both metals reach the required temperature they are pressed and forge welded together.
Video credits to Joining Technologies for Metals. It’s an actual lecture on flash welding (flash butt welding).
Resistance Projection Welding
What is Resistance Projection Welding?
Resistance Projection welding is a type of resistance welding that uses concentrates force, electricity, and time on projections (raised segments) to join pieces together. RPW can force welds to occur in very tiny, specific locations while also minimizing the dissipation of heat to other metal sheets.
RPW (or Resistance Projection Welding) is typically used in the auto industry, where screw fastener parts (nuts and studs) are joined to metal sheet components. One can also find Resistance Projection Welding in bar and cross wire welding.
Video credits to Supinder Singh. It shows Projection welding for cross welding.
Upset Welding
What is Upset Welding?
Upset Welding or Resistance Butt Welding is a welding process that merges either the entire surface of 2 nearby surfaces or progressively along a joint, via the heat from the resistance to the electric current through the area where those surfaces are in contact. Pressure is then applied before the heating of the metals is started and maintained during the heating period.
Upset welding uses the similar equipment to that used during flash welding and can only be done if the metals being welded are equal in cross-sectional area. The abutting or nearby surfaces must also be prepped carefully to make sure they’re ready to be heated properly. The difference Upset Welding has with Flash Welding is that the parts are clamped in the welding machine and force is applied which brings them tightly together. A high amperage current is then passed through the joint which heats the surfaces. When the heat s suitable for forging an upsetting force is applied and the current is applied. The high temperature of the work at the abutting surfaces plus the high pressure causes coalescence to take place.
Video credits to Maneklaxports. it shows an upset butt welding machine.
What are the High Energy Density welding processes?
High Energy Density Welding is made of welding processes that utilize heat sources capable of proving extremely high-power-density weld input levels. The density of the energy available from a heat source for welding is oft more important than the absolute source energy. Two of the major types of high energy density welding processes are Laser Beam Welding and Electron Beam Welding. Both of these welding processes use a high intensity beam as the heating source for the weld in which the energy from the source is highly concentrated by electromagnetic or optical lenses.
Electron Beam Welding
What is Electron Beam Welding?
Electric Beam Welding is a fusion welding process that uses a beam of high velocity electrons to join materials. The kinetic energy of the electrons is transformed into heat upon impact on surface of the working material. The work-piece and (possibly) filler metal, if used, melts to form a part of the weld. The welding is often done in conditions of a vacuum to prevent dispersion of the electron beam.
Most metals can be welded with electron beam technology, but the most common are:
- Superalloys
- Reactive and Refractory Metals
- Stainless Steels
Electron Beam Welding isn’t limited or controlled by thermal conduction. This allows metals to be welded to one another using high thermal conductivity, or joint designs with asymmetric heat transfer characteristics.
Video credits to Engineer’s Academy. It discusses Electron Beam Welding.
Video credits to EB industries. It goes over the differences between Laser Beam and Electron Beam Welding.
Laser Beam Welding
What is Laser Beam Welding?
Laser Beam Welding is a welding process that joins pieces of metal / thermoplastics by using lasers. The laser beam is a concentrated heat source that allows for the creation of deep, narrow welds as well as high welding rates. This welding process has been automated in several industries such as the automotive industry.
