Flux-Cored Wire versus Solid Wire

What are the differences between flux-cored electrode wire and solid electrode wire?  Is one type of electrode better than the other for welding?  What are the advantages and disadvantages of each type of wire?

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Flux-Cored Wire Electrodes

There are two types of flux-cored wire electrodes: gas-shielded and self-shielded.  As its name implies, the gas-shielded type of flux-cored wire requires an external shielding gas.  The self-shielded variety does not.

The flux coating on gas shielded flux-cored wires solidifies faster than the molten weld material.  Consequently, a sort of shelf is created which holds the molten pool when welding overhead or vertically up.  Gas-shielded flux wires work well when welding thicker metals.  They also work well for welding out-of-position applications.  Slag removal is easy with this type of wire. 

Self-shielding flux-cored wires do not require an external shielding gas.  With this type of electrode, the weld pool is protected as gas is generated when the flux from the wire is burned.  Because the self-shielding wire produces its own protective shield and doesn&#;t require an external gas tank, it is more easily carried about.

Advantages of Flux-Cored Wire Electrodes

There are several advantages of using flux-cored wire electrodes.  These advantages include but are not limited to:

• They allow for a high deposition rate.
• They work well outdoors and in windy conditions.
• With the right filler materials, these electrodes can make FCAW an &#;all-position&#; process.
• Typically, flux-cored wires create clean, strong welds.

Disadvantages of Flux-Cored Wire Electrodes

There are concerns with any type of welding method.  Regardless of the process and type of electrode used, there is the possibility of creating an incomplete fusion between the base metals.  Slag inclusion or cracks in the welds may also result.

Additional problems that may arise when using flux-cored electrode wires include:

• A melted contact tip may occur if the electrode contacts the base metal and fuses the two together.
• If gases do not escape the welded area before the metal hardens, the weld may develop holes and become porous.

Solid Wire Electrodes

Solid wire electrodes are used in Metal Inert Gas Welding.  Such electrodes require a shielding gas, which is delivered from a pressurized gas bottle.  The shielding gas protects the molten weld pool from atmospheric contaminants.    

Solid wire electrodes are often made of mild steel which is plated with copper to prevent oxidation and to aid in electrical conductivity.  The copper plating also helps to increase the life of the welding contact tip.

Solid wires are the best choice when working on thin materials, such as sheet metal.  They should produce nice, clean welds.

Solid wire electrodes do not work well in wind.  Exposing the shielding gas to the wind can compromise the integrity of the weld. 

Which Wire is the Best Choice?

When comparing the flux-cored wires to the solid wires, it would be wise to note that the best choice is dependent upon the welding job and location.  Both types of wires can produce sound welds with good weld bead appearances, when done correctly.

For thicker metals and outdoor jobs, the flux-cored wire electrodes work best.  For thinner metals and jobs performed out of the wind, solid wire electrodes can work quite well.

Solid wire electrodes used in MIG welding are not as portable as flux-cored wires.  This is due to the necessity of a shielding gas in MIGW.

Both solid wire electrodes and flux-cored wire electrodes are relatively easy to use.  However, flux-cored wire electrodes are more costly.

References:
www.millerwelds.com (The Miller Electric Manufacturing Co.)

http://en.wikipedia.org/wiki/Flux-cored_arc_welding

Additional Articles:

If you want to learn more, please visit our website Flux Cored Wire Gas-Shielded.

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What is Flux-Cored Arc Welding?

Comparing the advantages of flux cored vs. MIG

MIG welding and flux-cored welding possess different characteristics that welders must evaluate when selecting which process to use. To achieve the best results, consider the following factors: thickness of the material, proper shielding gas, wire feed speed and voltage settings, location of the jobsite, and weld appearance.

There is no one-size-fits-all welding solution, and all of the above variables will affect wire selection. This article will help the novice or occasional welders understand the basics of solid and flux-cored wire and how to maximize their advantages.

Solid wire/MIG basics

MIG power sources use a continuous solid wire electrode for filler metal and require a shielding gas delivered from a pressurized gas bottle. Mild steel solid wires are usually plated with copper to prevent oxidation, aid in electrical conductivity and help increase the life of the welding contact tip. The shielding gas protects the molten weld pool from contaminants present in the surrounding atmosphere. The most common shielding gas combination is 75% argon and 25% carbon dioxide. While welding outdoors, welders should use caution and prevent wind from blowing the shielding gas coverage away from the arc. Windshields may need to be used.

Flux-cored wire basics

There are two types of flux-cored wires &#; gas shielded and self shielded. Gas-shielded flux-cored wires require external shielding gas, and the slag is easy to remove. Consider using gas-shielded flux-cored wires when welding on thicker metals or in out-of-position applications. Gas-shielded flux-cored wires have a flux coating that solidifies more quickly than the molten weld material. As a result, it creates a shelf to hold the molten pool when welding overhead or vertically up. Self-shielding flux-cored wire does not require external shielding gas because the weld pool is protected by gas generated when flux from the wire is burned. As a result, self-shielding flux-cored wire is more portable because it does not require an external gas tank.

What to consider when choosing solid or flux-cored wire

Appearance

Many welders believe that weld appearance is an important factor. When working on materials less than 3/16-inch thick down to thin sheet metal (24 gauge), solid wire will produce a clean looking weld. For example, a short-circuit transfer with .030-inch solid wire set at 18-19 volts with 160-170 amps and using 75% argon and 25% carbon dioxide shielding gas will usually produce little spatter, create a smaller heat-affected area and reduce chances of burn-through. As a result, many automotive enthusiasts who specialize in bodywork or those who work with thinner applications prefer solid wire.

Location

The welder must also consider the location of the jobsite when choosing between solid and flux-cored wire. In environments such as windy locations, solid wire or gas-shielded flux-cored wire are more difficult to use because exposing the shielding gas to wind can compromise the weld integrity. Typically, the loss of shielding gas will produce porosity visible in the weld bead.

On the other hand, self-shielded flux-cored wire is ideal for welding outdoors or in windy conditions. The welder does not have to set up windshields to protect the shielding gases because the shielding gas is generated from the burning flux. Since self-shielded flux-cored wire does not require external shielding gas, it is also more portable than solid wire. This portability is ideal in agricultural applications where field equipment can break down far from the shop. If you are welding thicker metals (16 gauge and above), self-shielded flux-cored wire also provides excellent penetration.

Thickness, type of application and parameter settings

Many novice welders attempt to use a one-size-fits-all wire and shielding gas combination for multiple applications. The most common wire and gas combinations (for solid wire) are .035-inch- diameter wire used with a 75% argon and 25% carbon dioxide shielding gas. When welding thicker material, however, consider the welding power source output, as well as welding wire diameter. If using a .035-inch wire for thicker materials, and the power source is plugged into a 115-volt circuit, the resulting amperage output may not be sufficient to make quality welds. This increases the risk of cold lap or lack of fusion.

Attempting to use too small of a solid wire for thicker applications (such as on A-frames of an automobile) increases the chance of lower penetration in the root and could require more than one welding pass. Misapplication of the solid wire (even though strong enough) may also not provide adequate penetration on thicker material.

Although more expensive than solid wire, flux-cored wire could help you gain productivity. Flux-cored wire typically has the ability to weld dirtier materials that may have higher levels of rust, mill scale or oil. Although cleaning is always the proper method of preparing the steel, flux-cored wires contain de-oxidizing elements that trap these contaminants in the weld pool and hold them in the slag coverage, typically preventing the associated weld problems found when welding dirtier steels. When compared to solid wire, flux-cored wire also increases penetration on the sidewalls and offers the advantage of better deposition rates (the amount of weld metal deposited in a given time period, measured in pounds per hour). Although the welder is initially spending more for flux-cored wire, the savings are realized in the decreased production time.

Which is better, solid wire or flux-cored wire?

Neither wire is superior to the other. They simply have different properties that work better on certain applications. As far as performance is concerned, both wire types produce sound welds with good weld bead appearances when applied correctly and used within the proper parameter settings. Solid wire provides deep penetration in the root and usually has little spatter. Flux-cored wire has a larger ball-type transfer and produces low spatter levels. In addition, flux-cored wire produces a rounder penetration profile with excellent sidewall fusion.

As far as user appeal, both solid wire and flux-cored wire are relatively easy to use. This makes them ideal for novice and occasional welders working in automotive, farming and home hobby applications. Welders may prefer solid wire on thinner applications because there is no slag to remove, it is ready to paint and the weld beads may be more aesthetically pleasing.

A final word on flux cored vs. MIG

Most important, remember not to fall into the one-size-fits-all mindset. Solid wire, self-shielded flux-cored wire and gas-shielded flux-cored wire all work well &#; provided they are applied correctly. The type of wire you choose will be contingent upon the location of the jobsite, thickness of the application, proper shielding gas combination and the type of equipment available. You should always clean the workpiece before welding to ensure optimum weld quality and prevent impurities from becoming trapped in the weld bead. To achieve the best possible results, be willing to make adjustments based on the jobsite variables and consider having both solid and flux-cored wire available.

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