An electrode is a conductor that is used to make contact with a nonmetallic part of a circuit. Electrodes are commonly used in electrochemical cells, semiconductors like diodes, and in medical devices. An electrode is classified as either a cathode or an anode depending on if current is flowing into or out of the electrode. Conventional current flows into a device through its anode and leaves the device through the cathode. An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). The word was coined by William Whewell at the request of the scientist Michael Faraday from two Greek words: elektron, meaning amber (from which the word electricity is derived), and hodos, a way.

An electrode in an electrochemical cell is referred to as either an anode or a cathode. The anode is now defined as the electrode at which electrons leave the cell and oxidation occurs (indicated by a minus symbol, "−"), and the cathode as the electrode at which electrons enter the cell and reduction occurs (indicated by a plus symbol, "+"). Each electrode may become either the anode or the cathode depending on the direction of current through the cell. A bipolar electrode is an electrode that functions as the anode of one cell and the cathode of another cell.

Welding Electrodes

A welding electrode is a metal wire that is coated. It is made out of materials with a similar composition to the metal being welded.Welding electrodes are used to conduct current through a workpiece to fuse two pieces together. Depending upon the process, the electrode is either consumable, in the case of gas metal arc welding or shielded metal arc welding, or non-consumable, such as in gas tungsten arc welding. For a direct current system, the weld rod or stick may be a cathode for a filling type weld or an anode for other welding processes. For an alternating current arc welder, the welding electrode would not be considered an anode or cathode.

A welder needs a welding electrode to generate an electric current to do arc welding. In welding, an electric current is conducted through an electrode which is used to join the parent metals. When you keep the electrode tip near the parent metal electric current jumps from the electrode tip to the parent metal. The main purpose of electrodes used in welding is to create an electric arc. These electrodes can be positively charged anode or they can be negatively charged cathode.

Factors That You Must Consider Before Selecting Welding Electrodes

The electrode rod should have greater tensile strength than the parent metals. You have to consider joint design, shape, specifications of base metals and welding positions.

Types of Welding Electrodes

Basically, depending upon the process there are two types of welding electrodes:

Consumable Electrodes, Non-Consumable Electrodes

1. Consumable Electrodes: 

Consumable electrodes have low melting point. These types of welding electrodes are preferred to use in Metal Inert Gas (MIG) welding. For making consumable electrodes, materials such as mild steel and nickel steel are used. The one precaution that you must take is to replace consumable electrodes after regular intervals. The only disadvantage of using such electrodes is that they don’t have a large number of industry applications but at the same time they are easy to use and maintain.

Consumable electrodes are categorized as:

Bare Electrodes

Bare welding electrodes are made of wire compositions required for specific applications. These electrodes have no coatings other than those required in wire drawing. These wire drawing coatings have some slight stabilizing effect on the arc but are otherwise of no consequence. Bare electrodes are used for welding manganese steel and other purposes where a coated electrode is not required or is undesirable.

Light Coated Electrodes

Light coated welding electrodes have a definite composition. A light coating has been applied on the surface by washing, dipping, brushing, spraying, tumbling, or wiping. The coatings improve the characteristics of the arc stream. They are listed under the E45 series in the electrode identification system.

Shielded Arc or Heavy Coated Electrodes

Shielded arc or heavy coated welding electrodes have a definite composition on which a coating has been applied by dipping or extrusion. The shielded arc or heavy coated electrodes are used for welding steels, cast iron, and hard surfacing.

2. Non-Consumable Electrodes: 

These types of welding electrodes are also referred to as Refractory electrodes. As the name suggests, these types of welding electrodes are not consumed in the entire welding process or we can say more appropriately that they do not melt during welding. But practically, due to the vaporization and oxidation processes taking place during welding there is a little bit reduction in the length of the electrode. The non-consumable electrodes have a high melting point and are unable to fill the gap in the workpiece. Non-consumable electrodes are made from materials such as pure tungsten, graphite or carbon coated with copper. Non-consumable electrodes are used in Tungsten inert gas welding (TIG) and carbon arc welding.

There are two subtypes of non-consumable electrodes:

Carbon or Graphite electrodes: It is made up of carbon and graphite and mostly used in the applications of cutting and arc welding.

Tungsten electrodes: Basically, it is consisting of tungsten as the name itself suggests and it is a non-filler metal electrode

Classifications of Welding Electrode

The American Welding Society numbering system can tell a welder quite a bit about a specific stick electrode including what application it works best in and how it should be used to maximize performance. With that in mind, let's take a look at the system and how it works.

The prefix "E" designates an arc welding electrode. The first two digits of a 4-digit number and the first three digits of 5-digit number indicate minimum tensile strength. For example, E6010 is a 60,000psi tensile strength electrode while E10018 designates a 100,000psi tensile strength electrode. The next to last digit indicates position. The "1" designates an all-position electrode, "2" is for flat and horizontal positions only; while "4" indicates an electrode that can be used for flat, horizontal, vertical down and overhead. The last 2 digits taken together indicate the type of coating and the correct polarity or current to use. See chart below:

Digit Type of Coating Welding Current

0 High cellulose sodium DC+

1 High cellulose potassiumAC, DC+ or DC-

2 High titania sodium AC, DC-

3 High titania potassium AC, DC+

4 Iron powder, titania AC, DC+ or DC-

5 Low hydrogen sodium DC+

6 Low hydrogen potassium AC, DC+

7 High iron oxide, iron powder AC, DC+ or DC-

8 Low hydrogen potassium, iron powder AC, DC+ or DC-

As a welder, there are certain electrodes that you will most likely see and use time and time again as you go about your daily operations. A DC machine produces a smoother arc. DC rated electrodes will only run on a DC welding machine. Electrodes which are rated for AC welding are more forgiving and can also be used with a DC machine. Here are some of the most common electrodes and how they are typically used:

E6010: DC only and designed for putting the root bead on the inside of a piece of pipe, this is the most penetrating arc of all. It is tops to dig through rust, oil, paint or dirt. It is an all-position electrode that beginning welders usually find extremely difficult, but is loved by pipeline welders worldwide.

E6011: This electrode is used for all-position AC welding or for welding on rusty, dirty, less-than-new metal. It has a deep, penetrating arc and is often the first choice for repair or maintenance work when DC is unavailable.

E6013: This all-position, AC electrode is used for welding clean, new sheet metal. Its soft arc has minimal spatter, moderate penetration and an easy-to-clean slag.

E7018: A low-hydrogen, usually DC, all-position electrode used when quality is an issue or for hard-to-weld metals. It has the capability of producing more uniform weld metal, which has better impact properties at temperatures below zero.

E7024: Typically used to make a large weld downhand with AC in a plate that is at least ¼" thick, but more commonly used for plates that are ½" and up.

Before you power up your machine and pick up your electrode holder, learn more about welding electrodes, and how to buy quality products. Kindly contact us for more information.

4th Dec 2020 Ernest Orhuebor

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