Alexander is a professional engineer who specializes in the construction of affordable houses and structures using recycled materials.
So What is a Welding Electrode?
Before we move to the intrinsic details of welding tools and electrodes, let's first understand the meaning.
So what is Welding Electrode? In chemical terms, an electrode is a chemical element used to conduct electric current through to metals so as to combine it, otherwise, shape them. In layman's terms, it's a hot rod used to smelt and join two metals using electric current that sparks during use.
The welding electrodes used in arc welding are meant to pass the electric current from metal to metal while forming an arc. It will not matter whether the electrodes are negatively or positively charged, hence it could either be the cathode or the anode.
Now since you have an understanding of that, let's jump right into the types of welding electrodes available for use during modification of shipping container homes.
There are Three Types of Welding Electrodes
Types of Welding Electrodes
There are three distinct types of welding electrodes, they include;
- Consumable Electrodes
- Non-Consumable Electrodes
- Flux Electrodes
1. Consumable Electrodes
These types of electrodes are very easy to use even for amateurs and those doing DIYs. They have a rather low melting point compared to the other electrodes, hence used rarely. Most of its applications are with Metal Inert Gas (MIG) welding.
These consumable electrodes resonate well with two types of metal; namely steel and nickel. This is because they conduct precise welding at regular intervals, hence fits application with these metals. On the disadvantage side, they can only be used for small scale welding and not large industrial spaces.
Consumable electrodes are further subdivided into to other types;
- Bare Electrodes
- Coated Electrodes
(i) Bare Electrodes
As the name suggests, these electrodes do not need any upper coating during welding. Their application is hence easy and cheap.
(ii) Coated Electrodes
On the other hand, coated electrodes need to be covered while welding to protect its core wire. The coating of the electrode is determined by a coating factor, which is the ratio of the diameter of the electrode to the diameter of the core wire.
Depending on the coating factor, there are further categorized into these coated electrodes;
- Lightly coated - these have a coating factor of 1.25. They are majorly used to remove debris or impurities while welding such as phosphorus and oxides. Furthermore, the coating adds to the arc's stability during welding.
- Medium coated - a slightly higher factor of 1.45, they perform the same task as the light coated electrodes, but on a wider scale.
- Heavily coated - lastly, the heavily coated electrodes with a coating factor range of 1.6 to 2.2. It's also known as the shielded arc because of its heavy composition.
The coating is done with either three coats; cellulose coating, mineral coating, or both. Cellulose coating has a layer of inert gas around it to protect the weld zone, while mineral coating has minerals that form a slag during melting. For the shielded arc, it could be made of both, meaning it has the heaviest strength and composition compared to the other two.
Consumable electrodes have certain features; namely,
- They conduct thermal heat better and faster than the non-consumable electrodes. They are therefore better conductors and more efficient in welding.
- They can be made of various materials, as you shall read about below under the materials used to make the welding electrodes.
For the core wire, nickel is the best component used along with mild or low alloys.
Refractory Electrodes can further be sub-divided into:-
Other features of non-consumable electrodes include;
● They use different charge electrodes for different uses. The cathode, negatively charged, is what makes the electrode. The anode, on the other hand, will be the workpieces.
● They use inert gases to keep off flammable gases such as nitrogen and oxygen.
The two Other Types of Welding Electrodes
2. Non-Consumable Electrodes
These types of electrodes are also referred to as Refractory Electrodes. They are commonly used for TIG welding where the welding stick or SMAW doesn't actually melt like the consumables. They maintain their integrity during the welding process.
The non-consumable electrodes are also subdivided into two categories;
- Carbon/graphite - made of either of these materials they are mostly used for arc welding. They provide substantial stability during welding and cutting.
- Tungsten electrodes - a non-consumable electrode with a non-filler metal uses for welding as well.
Because the non-consumable electrodes are not smelted into the wires during melting, the arcs may bit be as precise. This, however, doesn't mean that it doesn't produce efficient work. They will also oxidize and vaporize any sulfur or phosphorus during the process.
They have a higher melting point bit no filler metal like the consumable electrodes. The materials range from pure tungsten, copper, graphite, and carbon. Chemically, all these have high melting points of over 3200 degrees Celsius.
Other features of non-consumable electrodes include;
- They use different charge electrodes for different uses. The cathode, negatively charged, is what makes the electrode. The anode, on the other hand, will be the workpieces.
- They use inert gases to keep off flammable gases such as nitrogen and oxygen.
The non-consumable electrodes are fairly easy to understand since they don't have many classifications. In terms of coating, they can be used bare with a coated layer of copper.
The best type here is the pure tungsten electrodes, green in color. In comparison to the yellow, red, or brown, pure tungsten doesn't have thorium hence stronger durability than with the alloy. They can work well with high current, providing more resistance.
The ones with an allot of Thorium and Zirconium provide better stability especially for cylindrical welding, but they can be difficult to maintain the high electric current passing through.
3. Flux Electrodes
This third classification is actually just a branch of the consumable electrodes. The only difference is that they have a flux coating. Unlike the inert gas used to shield the weld zone and offer additional protection, flux produces a cloud of gas during welding that will prevent oxides and sulfate from forming.
Because of that, the welded area will be smooth and clear once you're done with the process. There are different types of flux coatings you can apply. Speak to your engineer about the best to apply for a certain job.
Types of Welding Rods As Per The Material Used In Making Them
As mentioned above, the welding rod can be made of various metals, including carbon, graphite, steel, tungsten, and the likes. In this section, you will read about the different materials used to make the welding rods.
1. Steel Welding Rods
Steel is the most primarily used metal as it's easy to acquire and easy to use. It may rust over time, but it certainly costs less than other metals. You can also get alloyed steel in the market; these are those mixed with other products to make it a mild or low alloy.
They are great consumable electrodes and provide the stability needed to weld properly. They could also have a flux coating or not, depends on what you're looking for.
2. Bronze Welding Rods
A very rare metal used to combine garnet metals made of copper. Bronze has a strong tensile strength hence perfect for hard metals and for brazing.
3. Aluminum Welding Rods
The lightest of all metals, aluminum. Great with other aluminum parent metals during welding. It can be used for tungsten inert gas welding, arc welding, and MIG welding.
4. Composite Welding Rods
Finally, the composite is where the welding rod has been made of two or more materials. They are made into a layer so as to be stronger and to produce high-quality welding. The core can have a flux coating or but can simply be bare.
Factors to Consider When Selecting Electrodes
So what do you look for when you're choosing the electrodes? Most factors have already been discussed above as you've read the distinct features above. But a quick rundown of the characteristics to look at include;
- Tensile strength - for a shipping container home, you need the strongest type of welding rod to conduct electrical current properly to get the best results.
- Joint design - depending on where you want to weld, you would need a specific rod with a slighter smaller or longer diameter.
- Shape - this will further be elaborated below as you read about the electrode classifications.
- Base materials - from the description above on the materials used to make the electrode, you may need a specific material to cater to your needs. For example bronze for bronze.
- Welding positions - the rods have different arc abilities, some work best with straight welding while others are stable enough for different positioning.
Once you have all these in order, making the choice shouldn't be hard.
Classification of Welding Electrodes
There is a specific classification of welding rods that features the right diameter and size an electrode should be. For the consumable electrodes, the diameter cannot stretch any thicker than the metal being welded.
In most cases, you'll see a standard size of 3/32; or something between 1/16 to even triple that size. Other elements could be the iron powder content for steel rods. That can affect the welding power because the best have a percentage above 60.
For this segment of the article, you shall take a deeper look into the terminology of an electrode. How exactly is it classified?
So here's an electrode; E6018-X.
The first letter E just signifies that in fact, it is an electrode. The next two digits that follow represent the tensile strength. As you read earlier, the strength has to be higher than the parent metal, so as to have a quality weld. This strength is measured using psi which usually represents 1000 times the stated number.
So in this case, the strength is actually 60,000psi. The next number (1), represents the welding position. The numbers could be one, two, or four. In this case, one is a flat, horizontal, and vertical position. Two is for a flat and horizontal, while four is for a flat, horizontal, and vertically downward position.
The last number, (8) represents the type of coating used, as well as the current to be used. The number could also tell the type of penetration of the electrode ranging from low, medium, and deep. X is complimentary in that it mentions additional features. The letter is actually optional; stated only when the rod has extra desirable features such as;
-1: to indicate that the electrode is more ductile and sturdy.
-M: It is comfortable for military applications and low moisture content.
-H4, -H8,-H16: All represents maximum diffusible hydrogen limit measured in millimeters per 100 Grams. For instance, -H4 = 4 mL per 100 grams.
Specific Welding Rod Sizes
As we wind up, here are the common rod sizes you will see in the market.
Used for general welding applications. They mostly don't have special features but can be used in a versatile environment. For example in farm equipment, wrought iron, roadworks, and piping.
These electrodes have high cellulose sodium coating hence very strong for work. They have deep penetration and can pass through any impurities from dust, oil, paint, and rust.
These, on the other hand, have a high potassium coating. It can be used for both alternate and direct electric current, unlike for 6010. They also have a deep penetration status that can cut through dust, paint, and unclean materials.
The slag from this electrode is very little but hard to remove.
One of the best electrodes that can be positioned however you'd like. They are the best for joining and can be used at high speeds. Their disadvantages are that they produce a lot of slag and they have shallow penetration.
Very easy to use and produce a softer much clearer arc than the others. Work best for sheet metal. They are frequently used for repair on thin materials.
Also known as “low hydrogen electrode”, they have a low moisture coating that eliminates or reduces the hydrogen that gets into contact with the weld zone. Its welding quality is very high creating crack-resistant weld points with medium penetration.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2019 Alexander Okelo