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Posts Tagged ‘manual metal arc’

SMAW is commonly referred as shielded metal arc welding. It is also called as Manual Metal Arc (MMA). A consumable electrode which is coated with flux is used to make welds in this type of welding. The electric arc is formed by either using alternating or direct current as a power. This arc is formed between the metal and the electrode to weld. Shielding gas is formed when the flux which was coated on the electrode begins to disintegrate and produce vapors. This gas protects from air contamination too. Here are some basics that a welder ought to know when it comes to arc welding;

Electricity in direct current flows from negative to positive. Direct current is used to produce smooth welding. Electricity passes to and from negative and positive on a sine wave. This results in an irregular passage of current. In turn this results in more spatters.
Reverse polarity is called as Direct Current Electrode Positive (DCEP). Direct Current Electrode Negative (DCEN) is called as straight polarity. Electricity passes with great concentration into the welding rod’s tip to provide just a quarter less that it is capable in DCEP. This gives great incursion. Thick steel pieces can be weld easily with DCEP.

But in DCEN current passes out of the welding rod. There is one third of heat that is concentrated on the rod. This eventually results in less incursive capability. Therefore serves to the best power for thin steel.

There are scores of people who believe that DCEN gives great penetration than DCEP. But with experience you should be able to take sides on your own.

There are a few weld defects that SMAW can cause. They are slag inclusion, undercut and porosity. They are called defects as they weaken the joints where welds are made. Porosity is the holes that appear on the welds. This may be due to gas or steam.

- Slag inclusion happens you don’t chip off the slag. A welder should always get rid of the slag.
- Undercut is the primary mistake that should not happen while welding.
- It is very harmful to weld with exposed skin. Radiations from ultra violet rays can be brutal to your skin. They are capable to blister the cornea of your eyes. Exposing skin while welding leads to skin cancer. The primary reason why heavy welding coats are avoided by welders is because they are uncomfortable. It is not a great reason when compared to the harm that welding can pose on your body.
- Spatter is the molten metal drops that get stuck to the metal all around the place your weld. Spatter will chip off by itself.

Related Shielded Metal Arc Welding Articles

Welding Machine is equipment, which is used to weld or joint two metals or alloys together using another metal component as filler. Usually structure-less metals and alloys are joint using welding machines to give them desired shape and make them sturdier than they would be if it were a single piece.

These machines are available in different sizes as per their utility. A large size machine would be used in a factory and a handy machine is available for domestic purpose. Types of machines that are available in the market vary from Arc welding machine, Fusion-welding machine, Plasma Cutting machine, Resistance welding machine, Solid State Welding machine and less known types are Induction and Thyristorised welding machines.

Among all the types, Arc type machines are the most efficient and effective. According to the type of material used to weld, they are broadly classified into three categories.

Common most is the Manual Metal Arc mechanism. The tool looks like a stick, which performs the function of a main electrode, and it is covered by a flux that prevents it from oxidization. With the help of electricity, the electrode melts itself continuously for welding the metal. This equipment is mostly used for small tasks. This kind of machine is usually used in construction industry, maintenance and repair of small metals, cutting and making holes in steel products and rebuilding fixtures.

Second form is a Metal Inert Gas mechanism which is a large bobbin like formation. It is a single piece of equipment that includes a mix of argon or helium gas or both used along with the heated electrode to camouflage the metal from rusting. This makes the task easy and quicker. Metal Inert Gas equipments are mainly used in shipbuilding, power plants, aerospace equipments, automobile industry, bridge constructions and refineries.

The third kind is Tungsten Inert Gas, which has a single electrode, and the protective material is provided by another resource. The electrode does not thaw out as it has an additional tool to give it protection. This type of mechanisms is used in large factories where it is impossible to use other type of welding machines. Principally, Tungsten Inert Gas machines are used in power plants, construction industry, aerospace industry and manufacturing industry for more robust and specialized welding.

Apart from these, other type of welding machines that are available in the market are:

Carbon Arc, which is used for welding alloy steel and water jet cutting.
Orbital or Tube Arc is used in casting, shipbuilding, automotive industry etc.
Plasma Arc is used for welding of surgical instruments, food industry, dairy industry etc.
Stud Arc is mostly utilised in fabrication and machining.
Submerged Arc is chiefly used in industrial welding and pipe welding.

Any industry usually uses a combination of any of the above machines as per requirement. Welding machines are easy to use but is a complex piece of machinery and hence should be operated under expert guidance.