Shielded metal arc welding (SMAW).
Shielded metal arc welding (SMAW) is also known as Manual metal arc welding (MMA or MMAW) or stick welding (SW) or flux shielded arc welding (FSAW). Shielded metal arc welding one of the world's most first and popular welding processes. Shielded metal arc welding extensively in the construction and heavy steel structures and industrial fabrications. It is mainly used in pipeline and mechanical related work to join two metals.
Shielded metal arc welding is a manual process that is used to join the metal with the help of an electrode and power supply. Shielded metal arc welding is a technique in which flux is created between the base metal and filler materials. Electrodes that help create weld joint, filler material (electrode) melts to form a weld pool, Electrode coated with the flux coating that giving off a vapor that serves as shielding gas and that providing a layer of slag on the weld to protect ( or defect-free welding) the weld area from atmospheric contamination, after welding weld pool solidifies to join previously separated material sections.
Shielded metal arc welding can be used for weld of most of the materials, as like Carbon steel, stainless steel, nickel alloy, cast iron, etc. Consumable electrodes covered with a flux to lay the weld metal. Shielded metal arc welding is the most popular and versatile welding process, because of the simplicity of its operation and simplicity of its equipment and operations.
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| Shielded metal arc welding |
The actuals weldings technique depends upon the electrode and the compositions of the workpiece, and the positions of the joint being welded. And welding speed depend on the choice of the welding electrode and welding positions. In the case of a flat weld joint require fewer operator skills. The quality of the shielded metal arc welding is poor because of slag inclusion, porosity, spatter, poor fusion, shallow penetration, cacking. Due to all these possible defect costs of the shielded metal arc welding is increasing. But it is more dependent on the welding operator skills. It can be used in all positions.
Do you want to know about (SMAW) welding variables for welding procedure specification (WPS) and welding procedure specification, to click these links?
SMAW welding variables for WPS
Welding procedure specification (WPS)
Shielded metal arc welding can be used for weld of most of the materials, as like Carbon steel, stainless steel, nickel alloy, cast iron, etc. Consumable electrodes covered with a flux to lay the weld metal. Shielded metal arc welding is the most popular and versatile welding process, because of the simplicity of its operation and simplicity of its equipment and operations.
Process of SMAW
In the shielded metal arc welding need to be a constant power source. The power source of the shielded metal arc welding either in form of alternating current or direct current, that is used to produce an electric arc between the electrode and base metal to be joined. When the electrode partially strikes on the base metal for a short time it generates an arc then after maintaining a proper distance between the base metal and electrode for the continued arc for fusion. The base metal and the electrode melts and forming a pool of molten metal, after cools to form a joint. As the weld is laid, Electrode coated with the flux coating that giving off a vapor that serve as shielding gas and that providing a layer of slag on the weld to protect the weld area (defect-free weld) from atmospheric contamination.
Power supply
Shielded metal arc welding needs a constant current power source. SMAW welding power source has two terminals one terminal connected to the base metal and another terminal connected to the welding holder which holds the electrode and also gives the power supply to the electrode. When a positive terminal connected with the electrode then it is called Direct current electrode positive or reverse polarity (DCEP). It has about 70% heat, which gives good penetration so it is mainly used for thicker steel. DCEP is the electron flow close to the electrode. And when the negative terminal connected with the electrode then it is called direct current electrode negative or straight polarity (DCEN). It has about 30% of heat on the electrode hence penetration is less so it is mainly used for thinner steel. DCEN is the electron flow from the tip of the electrode. There are no Negative and positive terminals in alternating current.
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| SMAW connection. |
Safety Equipment
Personal protective equipment (PPE) and clothing.
Hand gloves.
Apron and heat resistance jacket.
Welding helmet classes 3 and 4.
Goggles class 2C.
Respirators (mask) class 7B.
Earplug.
Boot.
Face shielding Class 6B.
Basic Equipment
Power supply.
Welding machine.
Welding cables.
Electrode holder.
Electrode.
Base metal.
Ground clamp.
Advantages of SMAW
Lightweight equipment.
Easy to portable.
Good in tight space.
No need for separate gas shielding.
The cost is 30 to 50 percent less than the other methods.
Electrode availability is very easy.
Cleaning the metal surface before welding, not as rigorous as another method such as TIG.
Good for maintenance work.
Easy in operation.
Disadvantages of SMAW
Need to remove slag after each welding pass.
Need to stop welding every electrode end.
Stop the welding every end of the electrode.
Waste of the last portion of every electrode.
Less deposition.
Less productivity.
Spatter is more than other welding processes.
Slow reactive speed.
Need to be a removal of Slag and spatter.
Create more heat and spark than other welding methods.
During chipping and grinding gives more harmful dust.
Uses of SMAW welding.
Weld Carbon steel.
Steel & Stainless steel.
Nickel alloy.
Cast iron.
Low and high alloy steel.
Ductile iron.
Copper.
Aluminum (In rare cases).
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