What is Welding ?
"Welding is the process of fusing (Joining) two pieces of metals (also called Workpieces) together". This is practiced by passing electric current from the welding electrode to the workpiece that makes an electric arc.
The electric are heats and dissolves the two metals together, which thus, fuses the two metals together resulting more grounded bond. The welding machine supplies the electric flow which is either in the form of alternating current (AC) or direct current (DC).
What is a Welding rod ?
Welding electrode, commonly referred to as a "Welding rod", is a component of a flux-coated metal wire that acts as a filler when utilized in a welding process called "Shield metal arc welding" or "SMAW".
In the SMAW process, also commonly mentioned as "stick welding", the welding rod (a.k.a "stick" electrode) melts along with the workpiece, acting as Filler. Because of this action, the welding rod is generally categorized as consumable electrode type.
In TIG welding, the welding rod doesn't melt, so they are categorized as non-consumable electrodes.
The welding rod is primarily consisting of a metal wire (or) rod (Steel, Aluminium, Bronze) and its outer flux coating. This metal rod melts and becomes part of the weld when the electric arc is created. This metal rod should generally be the same (or) identical material to the workpiece. However, there are welding cases that the welding rod and workpiece are of dissimilar materials.
The flux coating is the material that decomposes into a shielding gas during the welding process. The gas shielding protects the weld pool (the molten steel) rather than being contaminated by the atmospheric gas. A part of these flux coating likewise turns into a kind of plaque known as Slag, which protects the weld as it cools.
What's in the name of a Welding rod ?
The American Welding Society (AWS) has designed an Alpha-Numeric system for naming welding rods.
If we would take E 7018 welding rod as example, we would notice that there is one Alfa digit (E) and four numerical digits (7018). For starters, the letter 'E' stands for 'Electrode'. Take note of this to make sure you are using the right kit for the job!
The first two numbers of 7018 correspond to the tensile strength or the stress bearing capasity of the weld bead. Therefore, in the case of 7018 welding rod, the weld bead can withstand 70,000 lbs. per square inch. For this reason, the higher the first two numbers, the greater the strength of the electrode (1 lbs = .45 kgs).
The first two numbers of 7018 correspond to the tensile strength or the stress bearing capasity of the weld bead. Therefore, in the case of 7018 welding rod, the weld bead can withstand 70,000 lbs. per square inch. For this reason, the higher the first two numbers, the greater the strength of the electrode (1 lbs = .45 kgs).
The third digit, on the other hand, represents the number of positions in which the welding rod can be used. It is important to remember that there are four primary welding positions, namely the Flat, Horizontal, Vertical, and Overhead positions. A number "1" on the third digit (7018), therefore, basically means that it can be used for all four welding positions.
The last digit should be read in conjunction with the second-to-last number: together,however, refers to the coatings used on the electrodes. Electrodes are usually coated with varying chemicals to protect the joints while welding. These chemical coating can determine the amount of current applied in the welding process. Moreover, the welding power supply varies depending on the amount of current required in the welding process. The power supply is as simple as a car battery (or) as advanced as a high-frequency inverter that uses IGBT technology and can be controlled by a computer.
See the below table for full list of stick electrode classification based on coatings and the necessary welding currents based on the last two digits of the classification code.
Credits: Wikipedia
The last digit should be read in conjunction with the second-to-last number: together,however, refers to the coatings used on the electrodes. Electrodes are usually coated with varying chemicals to protect the joints while welding. These chemical coating can determine the amount of current applied in the welding process. Moreover, the welding power supply varies depending on the amount of current required in the welding process. The power supply is as simple as a car battery (or) as advanced as a high-frequency inverter that uses IGBT technology and can be controlled by a computer.
See the below table for full list of stick electrode classification based on coatings and the necessary welding currents based on the last two digits of the classification code.
Electrode Table
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ELECTRODE DIAMETER (THICKNESS)
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AMP RANGE
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PLATE
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1/16"
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20 - 40
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UP TO 3/16"
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3/32"
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40 - 125
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UP TO 1/4"
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1/8”
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75 - 185
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OVER 1/8"
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5/32"
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105 - 250
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OVER 1/4"
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3/16"
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140 - 305
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OVER 3/8"
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1/4"
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210 - 430
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OVER 3/8"
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5/16"
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275 - 450
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OVER 1/2"
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Credits: Wikipedia