This article discusses about the topic SMAW welding. SMAW stands for Submerged Metal Arc Welding. The name of this type of welding gives us an idea that the metal electrodes is submerged in some kind of fluid.
SMAW employs a consumable electrode which has a protective coating on it. When the electrode starts melting, the coat starts wearing off and then protects the weld pool oxygen and other atmospheric gases. In this article we shall discuss about SMAW in detail.
What is SMAW welding?
SMAW or Submerged Metal Arc Welding is a process in which the electrode itself has a coating which melts and protects the weld pool from contaminating gases like oxygen and other atmospheric gases.
An electric arc will be forming between the tip of the electrode and the surface of work piece. The electric arc is formed when the electrode is touched and electric current is passed through it. The arc forms as soon as the electrode is lifted by some distance. Due to the electric arc, excess heat is generated which melts the electrode and the coating on it.
SMAW welding process
SMAW welding process is a type of welding in which the coalescence of metals takes place by the heat generated from the electric arc generated between the electrode and the surface of the work piece.
When an alternating current or direct current is applied on the electrode, an electric arc is formed between the electrode and work piece. The electric arc is formed when the electrode is lifted by a small distance from the work piece. The electric arc produces enough heat that can be used for welding two metal pieces.
SMAW welding diagram
The welding diagram of SMAW process is shown below-
Image credits: Wikipedia
SMAW weld symbol
There are many types of symbols which represent different types of welds. The SMAW is represented by the following symbol-
SMAW welding machine
An SMAW welding machine is an assembly of certain equipment used to perform SMAW welding process. The machine requires a consumable electrode and electric supply.
The major equipment is the power source of SMAW process that may include- welding transformer, a dc rectifier or a dc generator set. A consumable electrode is used which has protective coating which melts when heat is produced on the weld area. When the coat melts, it provides shielding to weld pool from gases like oxygen and other impurities.
SMAW welding temperature
The SMAW welding process requires the electrode to reach a particular temperature to melt and for welding to take place. The electric arc will be generating the heat.
On an average the SMAW process requires around 11,000 Degrees Fahrenheit or 6100 Degrees Celsius for the welding to take place. The temperature depends on the magnitude of electric current passed through the electrode.
SMAW welding electrodes
In industry there are four common types of electrodes used for welding. They are flat, horizontal, vertical and overhead.
These are further named depending on the material properties. In SMAW process electrodes named 6010, 6011, 6013, 7018 and 7024 are used. Their diameters range from 1/8 to 5/32 inches. These electrodes can work in all the positions except 7024.
SMAW welding technique
The SMAW welding process can be started by two techniques. They are listed below-
- Scratch start technique– The name tells us that scratching of two things is taking place which in this case is electrode and work piece. The electrode will light up when an optimum distance between the work piece and electrode is made.
- Tapping technique– As the name suggests, the electrode is tapped on the surface of the work piece. When an optimum distance is achieved between electrode and work piece, an electric is produced between workpiece and electrode.
SMAW welding circuit
The SMAW welding circuit includes the following parts-
- Power source- It provides the necessary voltage difference to create the electric arc between the work piece and the electrode.
- Welding cables- The welding cables hold the electrode as well as provide current to the electrode.
- Electrode holder- As the name suggests it holds the electrode firmly.
- Ground clamp- Ground clamp fixed the work piece tightly so that it does not move while welding is taking place.
- Base metal- The base metal is the metal on which welding is going to take place.
- Arc welding electrode– Arc welding electrode is the electrode having a coating on it which shields the weld pool after melting.
SMAW advantages and disadvantages
The advantages and disadvantages of SMAW welding process are given in the section given below-
Advantages
- The equipment cost is lower than other conventional methods of welding.
- Change from one material to another is easy.
- Deposition rates are faster in SMAW
- The apparatus is easy to shift from one place to another.
- There is no need of shielding gas.
Disadvantages
- The deposition rate is still lower than GMAW
- The cost of filler metal per length is higher
- It needs more hand eye coordination
- The slug must be removed
- Production speed is lower
How to calculate travel speed in SMAW welding?
Welding speed is important to calculate so that we can know the time it will take to complete the welding procedure. The travel speed in SMAW welding can be calculated by the following formula-
Travel speed= Length of weld/ Time to weld
The units of travel speed are mm /s, inches /sec or cm /s.
Why is SMAW good for welding outdoors?
No special gas is required for shielding in SMAW welding process. The equipment used in SMAW process can be moved from one place to another.
The slug can be removed by light and medium winds. The weld area can be cleaned by the wind blowing outside. Hence it is recommended to perform the SMAW welding process outdoors.
SMAW welding vs TIG welding
The table below shows the comparison between smaw and tig welding
| SMAW Welding | TIG Welding |
| The smaw process uses a consumable electrode | A non consumable electrode is used in this process. |
| The electrode is non reusable | The same electrode can be used again for another round. |
SMAW welding vs GMAW
The table below shows the comparison between smaw and gmaw
| SMAW Welding | GMAW Welding |
| The electrode used in the smaw process cannot be reused and it is consumable | The electrode used in the gmaw process is also consumable and cannot be reused like in SMAW process |
| The machine needs to be stopped to change the electrode. | The machine need not be stopped because the electrode is automatically fed to the system by the spool |
SMAW welding vs fcaw
The table below shows the comparison between smaw and fcaw welding process
| SMAW Welding | FCAW Welding |
| The electrode used in the smaw process is covered with an inert gas used for shielding | The flux will be filled only at the core of electrode. Unlike the electrode used in SMAW process. |
| Electrode used in this process is consumable. | The electrode used is consumable like in smaw. |
SMAW vs Gtaw welding
The table below shows the comparison between smaw and gtaw welding
| SMAW Welding | GTAW Welding |
| The electrode is consumable | The electrode is non consumable and re usable |
| The electrode has inert gas coating which keeps melting | The shielding gas is fed externally from the cylinder |
Summary
We have discussed about SMAW welding process in this article. We also discussed about various other welding processes. We saw that SMAW welding requires a consumable electrode which has a coating that on melting protects the weld pool from harmful gases. Gases can penetrate inside weld pool and affect the strength of weld.
Hi ….I am Abhishek Khambhata, have pursued B. Tech in Mechanical Engineering. Throughout four years of my engineering, I have designed and flown unmanned aerial vehicles. My forte is fluid mechanics and thermal engineering. My fourth-year project was based on the performance enhancement of unmanned aerial vehicles using solar technology. I would like to connect with like-minded people.
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