Flux-Cored Arc Welding (FCAW) utilizes a continuously-fed tubular electrode, electrical power to melt the electrode, and may or may not use shielding gas from an externally supplied source when depositing material in the weld joint. The flux-cored electrode is a composite tubular filler metal consisting of a metal sheath with a core of mineral compounds and powdered metals. The resulting weld bead is covered by a residual slag (melted and solidified flux) which helps to protect and shape the finished weld, and is generally easily removed upon completion of the weld. Flux Cored Welding combines the high productivity of MIG welding using a solid electrode with the ability to weld on more contaminated base material. When compared with MIG welding, higher deposition rates are possible, especially when welding out of position.
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The type of Flux Cored Welding wire used depends on the welding position, the mechanical properties required, the type of joint and its fit-up, and the environment in which the welding is to be performed. Generally, self-shielded wires are used for welding outside or for special applications such as welding galvanized steel. Among the most common are outdoor construction and fabrication in areas where gas cylinders and gas shielding cannot be readily used. Gas-shielded flux-cored wires are used in operations such as shop fabrication, maintenance, and shipbuilding. Flux-cored wire welding is especially useful where the base material to be welded has some amount of scale, rust or other surface contaminants present. With the proper selection of wire type and shielding gas, weld properties are excellent for many types of materials.
All-position wires (E-71T-1) are typically smaller than 1/16&#; in diameter and are formulated with a fast-freeze flux. They are not well suited for use where high levels of base metal contamination exist, but offer good control when welding in the vertical up or over-head position. Shielding gas selection can be pure CO2 or C25. In all instances, the shielding gas selected should be matched with the recommendation of the filler metal manufacturer. Failure to do so may result in poor quality welds. A common problem from incorrect gas selection is weld cracking.
Flat-position wires (E-70) can be utilized in the flat or horizontal welding positions. They are typically greater than 1/16&#; diameter and are primarily applied for high deposition welding on thicker base materials (>1/4&#;) This family of wires offers a greater resistance to base metal contamination, and they have been shown to perform well over some rust and mill scale. Good welding practice dictates that the base metal should be cleaned of contamination prior to welding but, if this is not possible, these wires are the preferred choice.
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Welding is a large field.
&#;Welding&#; is any method of joining two materials together. While welding often refers to joining metal pieces, welding can apply to other materials, including plastic and wood. Because of this variety, numerous kinds of processes are used to weld materials together. Even something as simple as glue can be considered a welding method.
However, we&#;re not concerned with those sorts of welds today. Instead, we&#;re talking about welding metal. With metal welding, you might use four main processes in a typical shop: MIG welding, TIG welding, Stick welding, and Flux-core welding.
These four kinds of welding are called &#;arc welding&#; since they use arcs of electricity as the key to their processes. Setting MIG and TIG aside, let&#;s discuss Stick and Flux-core welding today.
Gas and Slag
Two essential elements of arc welding are the use of gas and the production of slag. These are critical differences between MIG and TIG welding and Stick and Flux-core welding.
MIG and TIG welding is known as &#;gas welding&#; because they use a shielding gas. The shielding gas creates an isolated atmosphere around the work area, which pushes away environmental oxygen, hydrogen, moisture, and other reactive substances that would otherwise penetrate, react with, or compromise the weld. We&#;ll cover that in greater detail in another post.
In MIG and TIG welding, gas is fed through the welding gun, shielding the area with its isolated atmosphere. Conversely, stick and flux-core welding produce their own gas on-site using flux.
Flux is an additive used to help promote clean, smooth welds. It does this in two ways:
Flux burns into a gas, which creates a shield similar to the shield pumped in by MIG and TIG welding.
Flux melts in place and floats to the top of a heated work area, shielding the molten weld from environmental impact as the shielding gas dissipates.
The melted flux that hardens on the outside of a weld is known as slag. This slag is excess material typically cleaned off the weld when the weld is completed.
So, the primary difference between gassed welding (MIG and TIG) and gasless welding (stick and flux-core) is the presence of flux.
A few considerations with gasless welding make it more practical for specific projects than cleaner gassed welding:
Since the gas is produced
in situ,
gasless welding can be done outdoors in windy conditions that would interfere with shielding gas from gassed welding.
Because slag is produced from burning flux, welders using gasless welding must always pull the electrode to avoid pushing slag too deep into the weld and creating slag intrusions, which compromise the integrity of the weld.
Gasless welding creates many more fumes than gassed welding, making it potentially more dangerous to use in enclosed spaces or spaces without adequate ventilation.
These are concerns with both stick and flux-core welding alike. So, what are the differences between stick and flux-core welding?
How Stick Welding Works
All forms of arc welding use a similar process. This process uses electricity to heat two pieces of metal into a molten state.
They also use a filler rod that melts in the same place. The three metals (piece one, piece two, and filler) melt together and solidify into a single strong joint.
One of the primary differences between the four kinds of arc welding is what filler material is used. The filler (or the &#;stick&#;) is a metal rod coated in flux in stick welding. This composition is why stick welding is called SMAW or Shielded Metal Arc Welding; the filler metal is shielded.
Electricity melts the joined materials and the stick with its flux coating, producing slag and a shielding gas on-site.
The Pros of Stick Welding
Stick welding has various benefits over other kinds of welding, which offset the cons we&#;ll discuss briefly.
First of all, stick welding can be very versatile. A wide range of electrodes can be used for different purposes and welds, lending them a lot of flexibility and utility. You can find stick welders that work off either 110v or 220v, and they&#;re pretty compact and easy to travel with.
Stick welding is also not very expensive.
Filler rods are pretty cheap, and since you don&#;t need inert gas tanks, you also save on that expense.
Stick welding can be used on metals that haven&#;t been thoroughly cleaned and prepared and can still produce a quality weld.
Another benefit is that stick welding is the least sensitive to contamination. It requires much less prep time than other forms of welding.
The Cons of Stick Welding
Stick welding is only perfect for some projects; if it were, there would be no need for other kinds of welding.
Stick welding is the most sensitive kind of welding to the skill of the welder. The resulting weld truly shows the skill level of the person welding the joint in terms of the presence of slag, the evenness of the weld, and other qualities.
While stick welding is resistant to contamination and dramatically reduces the need to prepare metal before welding, that savings is eliminated by post-welding cleanup.
Stick welding produces the most significant amount of slag out of any welding, so cleaning off slag is a considerable investment. Moreover, for multi-pass welds, you must clean them between each pass.
Stick welding can also burn through electrode sticks quite quickly. For longer welds, this means taking a break to switch electrodes in the middle of a weld, meaning you need to be able to tie your welds together appropriately.
Overall, stick welding is one of the most skill-intensive kinds of welding and the most prone to showing your mistakes.
How Flux-Core Welding Works
The primary difference between stick welding and flux-core welding is right there in the name; it&#;s all about the composition of the electrode. With stick welding, you have a metal electrode coated in flux. With flux-core welding, you have an electrode made out of flux coated in metal.
While it might not seem like this would make a huge difference &#; after all, both ingredients are right there in the rod &#; it&#;s pretty impactful.
In addition to the above, flux-core welding can only be used on ferrous materials like cast iron and mild steel and cannot be used on non-ferrous materials like aluminum.
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In many ways, flux-core welding can be compared to MIG welding, while stick welding is comparable to TIG welding. It&#;s easier to learn and somewhat more forgiving than its counterparts.
The Pros of Flux-core Welding
Flux-core welding has benefits that make it useful in certain situations.
Like stick welding, flux-core welding is ideal for windy conditions. It&#;s also great for welding materials with surface impurities that you can&#;t easily remove, like paint or rust.
One of the best benefits of flux-core welding is that it has a lot of leeway in arc distance and related factors. It can automatically adjust for changing conditions and correct for an unsteady hand.
This feature makes tackling specific projects more straightforward and approachable than stick welding.
Flux-core welders are also the most portable. You can plug them into a standard household 120v power supply, and since they do not need a gas tank, you can quickly move them from place to place.
The Cons of Flux-core Welding
Flux-core welding has a few drawbacks in addition to its benefits.
First of all, it&#;s the smokiest of the welding types. It produces the most smoke and gas and thus requires a well-ventilated or outdoor space to weld to avoid dangerous conditions.
It also produces the most heat. This quality makes it difficult to weld thinner materials and impossible to use on the most delicate metals because it will burn through them.
Also, like stick welding, flux-core welding produces a lot of slag and spatter, which must be cleaned up when the weld is complete.
Finally, flux-core welding is somewhat more expensive than stick welding. This difference is almost entirely because flux-core wires are more difficult to produce and, thus, more costly than flux-coated wires.
Comparing Stick and Flux-Core Welding
Leaving MIG and TIG welding out of the comparison, it&#;s easy to compare stick and flux-core welding directly.
1. Weld Quality
In terms of weld quality, both stick and flux-core welding heavily depend on the welder&#;s skill. All else being equal, stick welding will generally produce a slightly better weld, but both are more or less comparable. It&#;s also easier to weld in less-than-ideal conditions (such as when you have no time or ability to prep your metal) than MIG or TIG welding.
2. Welding Speed
Two different rates of speed can be necessary for welding: the weld&#;s speed and the filler material&#;s deposition rate. A slower deposition rate means a slower weld, but a faster deposition rate doesn&#;t necessarily mean a speedier weld; it can also mean a deeper or more thorough weld.
Stick welding is among the slowest welds in terms of speed and deposition rate.
Flux-core welding can be quite fast, allowing you to make emergency repairs and spot welds much quicker than other welding methods.
3. Heat Control
One of the most significant risks of welding is burning through the materials you&#;re trying to join, especially if those materials are thin. A welder must be able to control the heat used in the weld to prevent burn-through.
To an extent, different kinds of joints and joint preparations (such as bevels or J-grooves) can help mitigate this, but it&#;s very situational.
Stick welding has a slight advantage in terms of heat control. Flux-core welding is a hot process that relies more on movement speed to avoid burn-through.
4. Visibility of Work
One of the most significant drawbacks of flux-core welding is the high amount of smoke produced by the burning flux. While this is part of the shielding around the weld, it&#;s also the cause of a significant reduction in visibility. This drawback means that working in tight conditions, on narrow welds, or in places where precision is necessary, it can take time to get a good weld going with flux-core welding.
Stick welding is also not ideal for smoke and visibility, but it&#;s better than flux-core welding. Visibility is generally best with gassed systems, however.
5. Portability
Gassed systems are less portable than gasless systems since they require you to lug around cans of gas, additional hoses, and other tools. Between stick and flux-core welding, stick edges out in portability, as it needs less in the way of electrodes and other materials.
6. General Utility
Stick welding can be used to weld nearly anything. In many cases, the primary change you need to make is to the stick you&#;re using.
Sticks come in a wide range of different sizes, compositions, and styles, to facilitate all manner of welding.
Flux-core welding, on the other hand, is almost entirely limited to a few ferrous materials and thicker materials at that. While you can purchase some additional forms of electrodes for different kinds of welding, it&#;s generally more effective not to use the wrong tool for the job.
What Type of Welding is the Best?
This question is common among novice welders and newcomers to the trade. The truth is, there&#;s no single &#;best&#; kind of welding.
Each kind of welding has its pros and cons for the project, and the type of welding you use largely depends on the project, the materials, and the needs of the weld. Some welds perform better under stress, some are best used when the materials aren&#;t able to be prepared, and some are decorative.
Skilled welders learn at least the basics of all four kinds of welding to have a solid base of skills to use whenever welding is necessary.
Are you interested in learning how to weld using a gasless method? If so, consider renting equipment from us. We have an extensive range of welding machines, including flux-core and stick welders. If you&#;re unsure which welder you need for your project, contact us today, and we&#;ll point you in the right direction!
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