TIG (GTAW) welding is not the only process capable of producing high-quality welds on aluminum alloys. The high degree of control that the process provides makes it well-suited to tackling very thin materials, but as material thickness increases, the relatively slow speed of the process becomes more apparent. When ease-of-use and cost-effectiveness are prime considerations in an aluminum welding application, many fabricators choose to implement MIG (GMAW). While the process fundamentals are unchanged from MIG welding steel, MIG welding aluminum requires some specialized equipment and additional care to achieve high-quality results with minimal frustration.
Delivering the Aluminum Wire
Much of the additional care required is focused within the wire delivery system, since the lower columnar strength of aluminum wire makes it susceptible to burn-back and bird’s nesting. MIG welding aluminum typically requires fabricators to choose between “push-pull” or “spool gun” welding torches.
The Push Pull Gun:
Ideal when the workpiece can be brought within 15-25 feet of the power source
Advantages: Lighter and more maneuverable; can utilize wire packaging of any size (meaning reduced changeover cost)
Disadvantages: Reduced forgiveness to compounding issues in the feeding system
Regardless of the MIG welding gun being used, it is critical to ensure that the MIG consumables used are properly sized and in good condition. For example, both gun types require contact tips. Ensure that the wire diameter stamped on the contact tip matches the wire diameter being used and that the contact tip is inspected periodically for the formation of a keyhole shape at either end that is an indicator of wear. As the contact tip wears, micro-arcing between the contact tip and wire can lead to costly burn-backs that are prevented by a quick change of consumables.
A typical carbon steel MIG welding setup will typically use steel liners, brass inlet and intermediate wire guides, and either V-groove or V-knurled drive rolls. Users of a push-pull gun will need to go beyond simply changing contact tips. When MIG welding aluminum, it is important to use ALL the following: U-groove drive rolls, Teflon inlet and intermediate wire guides, and Teflon liners. Ensuring that these components are properly installed (and dedicated for aluminum use only) will help to minimize the potential for wire shaving that can cause the liner to become clogged and complicate wire feeding. Likewise, users of bulk wire packaging such as drums should carefully read the drum’s set up instructions and carefully consider the drum placement and conduit routing to help keep the overall “drag” in the system as low as possible.
Selecting Aluminum Welding Parameters
As with welding steel, it is possible to weld aluminum using one of several “transfers” depending on the specific wire feed speed and voltage combinations used.
Thin materials typically require a short circuit transfer that is the result of low wire feed speed and low voltage. These “low” settings help to minimize penetration to prevent burn-through from occurring. Attempting to use short-circuit on thick material without proper base metal preparation may lead to lack-of-fusion defects.
Thicker aluminum is best welded using a spray transfer. The higher wire feed speeds and voltages required to achieve the stable spray transfer provides additional penetration. Attempting to use spray transfer on thin aluminum will require significantly higher travel speeds than when welding using short-circuit.
Aluminum & Modern Pulsed Waveforms
“Pulse” is a feature found on many modern power sources where the output of the power source is “pulsed” between a low “background” and high “peak” current. By offering the “best of both worlds”, pulsed waveforms are beneficial when welding a wide range of common aluminum thicknesses. Using thinner material as an example: the “peak” current maintains a stable arc when welding at the “low” settings needed for thin material while the “background” current helps to keep overall heat input low to further minimize the risk of both distortion and burn-through.
Looking through a welder rental supplier’s catalog will reveal that there are many choices to be made when selecting aluminum MIG welding equipment. Consult with these experts to learn which combinations are best for your application; they may even have MIG welding packages which can help to alleviate some guesswork by bundling popular options together.
Before pulling the trigger, make sure to purchase some 100% Argon (or 75% Helium/25% Argon shielding gas for a little extra “punch”), set the flow rate to 35-50 cubic feet per hour, and always remove the oxide layer from the weld zone! With some modern technology and a little knowledge, achieving great results when MIG welding aluminum doesn’t necessarily have to be difficult.
Can you MIG weld mild steel to stainless steel? The short answer is, in most cases, yes and an ER309L filler metal is typically used. However, understanding the nature of stainless steel and MIG is helpful to best tackle this dissimilar-metal joining application. In this article we will discuss how this process is possible and what its applications are.
Why Join Mild Steel to Stainless Steel
Mild steel, as used in this article, refers to a wide range of steel grades/compositions having a relatively low overall alloy composition. On the other hand, stainless steel has a chromium content above 11% so that the surface of the steel forms a protective layer of chromium oxide. The chromium oxide layer provides enhanced corrosion resistance compared to mild steel in many applications. Despite this benefit, there are many applications where you might mix mild steel and stainless steel.
Cost is often the driving force behind the dissimilar joining: stainless steel is significantly more expensive than mild steel. Combining mild steel and carbon steel is one way to control the cost of a component while still ensuring that corrosion resistance is available in key areas. However, dissimilar-metal welding can sometimes be used to better allow components to carry required stresses, and in some cases, do so at a minimal component weight.
An Introduction to MIG
MIG is an acronym that represents Metal Inert Gas welding. MIG is one of many arc welding processes—processes that utilize an electric arc to melt the base metal and filler metal. A defining feature of the process is that it is a “wire-fed process” meaning that a continuously fed wire is used to maintain the electrical arc and provide filler metal into the weld joint. As the acronym suggests, MIG is also defined by the use of a shielding gas having generally inert characteristics that displaces the atmosphere from the weld zone to protect against detrimental reactions.
MIG is a very common process for welding mild steel, welding stainless steel, and welding these two metals to each other. MIG can be used with a range of shielding gasses and wire diameters to fine-tune performance for a wide range of material thicknesses. Because there is no slag, deposition efficiency (the ratio of filler metal consumed versus completed weld weight) is quite high. Because there is limited need for stop/starts and post-weld cleanup, operator factor (time spent welding versus total project time) can be much higher than other processes. These factors combine with the ability to achieve high travel speeds to produce a productive process. If you don’t currently own the equipment needed for MIG welding, welder rentals can be a way for you to become familiar with the process or tackle short-run production with limited investment.
How to Weld Mild Steel to Stainless Steel
Typically, ER309L filler metals are used to join mild steel to stainless steel. ER309L is a filler metal classification that designates:
That the filler metal can be used as an electrode for MIG or as a rod for TIG
That the filler metal has a 309 nominal alloy composition
That the filler metal is a low-carbon variant of the 309 nominal composition
ER309L is an austenitic stainless steel that is high in both chromium and nickel. The presence and quantity of nickel in this alloy helps to form a ductile weld microstructure. ER308/308L is a popular choice for joining 304/304L stainless steel to itself, but attempting to use this alloy for steel to stainless steel instead of ER309L may result in a crack-susceptible microstructure.
Shielding gas selection can influence the ease of welding and the quality of the results. Typically high-argon shielding gasses are used. 98% Argon/2% Oxygen or 98% Argon/2% Carbon Dioxide (CO2) are used for welding thicker materials, since these gasses help to achieve a smooth, stable spray transfer with minimal chemical interaction. Three-component gas mixtures, known as “tri-mixes”, typically consist primarily of helium with varying additions of argon and carbon dioxide. While not required for thin materials, they can offer improved performance when welding using the “short-circuit” mode of transfer commonly employed to help prevent burn-through or weld out of position.
Selecting parameters for steel to stainless steel weld joints is very similar to selecting parameters for welding stainless. The stainless filler metal requires a lower current to melt-off than mild steel filler metal, so expect to utilize lower wire feed speeds than you may be used to. Likewise, the weld pool will be more “sluggish” than when welding using mild steel filler metal, and penetration will be reduced. This means that you may need to use a wider included/bevel angle depending on the application to ensure good root and sidewall fusion. Try to avoid excessive heat input to minimize the risk of sensitization of the stainless steel base metal that can negatively affect corrosion resistance of that base metal.
Be aware that the finished weld is a mixture of alloys; the corrosion resistance of the weld metal will not be equivalent to the stainless steel base metal, and it may be important to locate these dissimilar weld joints away from sources of corrosion in some situations. Also be aware that not all stainless alloys are created equal. Stainless steel can be austenitic, martensitic, or ferritic which provides insight into their microstructure and typical compositions. Austenitic stainless steels—one of the most common types by tonnage—are generally easy to weld, while martensitic and ferritic stainless steels can be more of a challenge.
Next Steps
Contact us today to find the MIG welder that is best suited for the stainless to mild steel welding that you are looking to perform. “Sizing” a machine to your application can help you to get the feature set you need without unneeded expense. Our knowledgeable team can also provide guidance into the world of stainless steel and dissimilar-metal welding to help you select the best consumables, accessories, and knowledge.
Pound for pound of filler metal used, MIG welding (Metal Intert Gas, also known as GMAW) is one of the most popular welding processes. A key contributor to the success of the process is its versatility: it can produce high-quality welds with good productivity on a range of material thicknesses and compositions.
MIG welding uses a continuously fed wire electrode to transmit the welding arc and provide filler metal into the weld joint. The weld is protected from the atmosphere by an external shielding gas whose specific composition is often determined by the application, although as the name implies, it is largely inert.
Shop Fabrication & Manufacturing
Because a shielding gas is required, MIG is not commonly used for field fabrication and repair since providing protection from draft and breeze is time-consuming and can be difficult. Instead, self-shielded processes such as FCAW-S or stick welding (SMAW) are more popular.
The welding filler metal used may be solid or tubular. Tubular MIG welding wires/electrodes are often known as metal cored wires: they are a hollow tube filled with metal alloys. These tubular filler metals have some advantages over solid wires, such as potential deposition rate/productivity, although at the expense of per-pound filler metal cost. Metal cored wires are especially common in the fabrication of heavy equipment components and structural members.
Both solid and metal cored wires produce little to no slag, post-weld clean-up time is minimal, meaning parts can often be sent to downstream processes such as painting using only a light scrub with a wire brush. This makes the process very attractive for applications that demand high productivity, such as manufacturing.
Common Metals
The MIG welding process is used for welding carbon and low alloy steels, aluminum, and stainless steel. This means that it is common to industries ranging from boat and shipbuilding to chemical refineries.
Compared to steel and stainless steel wire, aluminum MIG wire takes special care in order to feed properly. Purpose-built components such as Teflon guides and liners, U-shaped drive rolls, and push-pull or spool guns are designed to help feed aluminum wire with less difficulty.
Filler metals for stainless steel welding are available in a wide range of alloy compositions ranging from the most common austenitic alloys (for example, 308L for welding 304/304L) to more exotic duplex stainless steels. MIG welding wires are even available for nickel super alloys, although many of these are tubular metal cored wires.
Thin & Thick Materials
MIG welding is frequently used for welding thin materials thanks to the availability of small diameter wires—0.023” to 0.035”—and pulsed waveforms. Both wire and waveform help provide a stable arc at the low amperages needed to produce a high-quality weld without burn-through or excessive weld size. Thin materials welded with MIG are often encountered when manufacturing automotive components. However, MIG is also an excellent process for the garage and home hobbyist.
MIG welding also exhibits good deposition rates and good performance at medium-to-high amperages, which means it is a popular choice for thick materials in addition to thin ones. Because the process is more easily observed during welding and used handheld than “faster” processes such as submerged arc, one could argue that the process is much more versatile and allows tackling a complex assembly with a single process. However, when thick metals must be welded out-of-position frequently, the gas-shielded flux cored welding (FCAW-G) process is preferable, since the slag offered by these consumables facilitates welding at amperages that help ensure good fusion along with good productivity. Fortunately, MIG equipment is often suitable for FCAW with only a change in filler metal and drive roll type.
An advantage of welder rentals is the opportunity to accomplish the task at hand with the equipment best suited for that task. If you don’t expect to weld thick material all the time, you can utilize heavy-duty equipment only when needed without the ROI demand and capital commitment of outright purchase. This is of extreme benefit to job-shop fabricators who can encounter everything under the sun, or field fabricators who may spend most of their time with an engine-driven unit but are able to utilize MIG infrequently, yet capitalize on higher productivity.
Pipe Welding
As mentioned, out-of-position welding may not be preferable for many MIG welding applications, but the process has exceptional performance when placing an open-root root pass on tubes and pipes. Because of the low amperages used, this may be done easily in- or out-of-position. Newer power sources have modified waveforms that help further the ease-of-use and weld quality root pass welding.
MIG welding may not be used for higher amperage fill and cap passes on pipes in a fixed position, but it is extremely popular when the pipe can be rotated. Typically, pipes ranging in diameter from 2-24” are welded using MIG, although there is some overlap with other processes at either end of this range.
Automation & Mechanization
MIG is one of the most popular processes for automation and mechanization. This is largely because the process is “semi-automatic”, allowing ease in programming and obtaining a high operator factor. The MIG welding torch is quite light, allowing ease of mounting to a range of robot arms. Special power sources offer improved ease of integration into the robotic system and welding cell, high amperage output and duty-cycle for improved travel speeds and uptime. Large drums of wire can be used to minimize downtime spent changing filler metal packaging.
Conclusion
MIG welding supports such a vast array of industries and applications that the ones mentioned above are by no means an exhaustive list. Instead, take these examples as inspiration to how MIG can be implemented into your operations. If you aren’t sure of the best route, contact us today to learn more about selecting the best welding equipment for your particular application. Our expert staff can also provide insight to productivity enhancing accessories, parameters, and techniques to ensure that your time spent MIG welding is successful!
How did the Dual Maverick 200/200X get its name? When you glance at the front panel of this diesel engine-driven welder, you might start seeing double: two front panels and two sets of output lugs. As the name implies, the Dual Maverick 200/200X is a dual-operator welding power source. The 24.8 horsepower water-cooled Kubota diesel engine in the Dual Maverick has the capacity to allow two welding operators to weld independently of one another.
The alternative is to supply each welding operator with their own engine-driven welding machine, but this approach has drawbacks. Placing this extra equipment on the jobsite creates additional clutter and requires additional maintenance. Likewise, the one welder/one welding machine approach is less fuel-efficient. Lincoln Electric claims that a multi-user welding machine like the Maverick Dual 200/200X can reduce fuel and maintenance expenses by up to 33% per 1000 hours, which equates to approximately one year of “typical” use.
When thinking about renting welding equipment, many contractors imagine visiting a local hardware shop with a small selection of soil compactors and other basic items. In reality, today’s rental solutions are nothing like that. You can find high-quality precision machinery maintained in optimal condition, from plasma cutters to TIG rentals
With professional welder rental, companies in countless industries are able to reach their goals on time and within budget:
Many businesses perform welding tasks every day, including parts manufacturers, vehicle makers, construction businesses and repair shops. People who enjoy do-it-yourself projects can handle automotive tasks or home repairs with a good arc welder. Thanks to welder rental options, you don’t even need to purchase welding equipment to get the job done.
Two popular types of arc welding equipment are metal inert gas (MIG) welding and tungsten inert gas (TIG) welding. What are the differences? How can you decide whether MIG or TIG welding is the right method for your application.
MIG Welding Process
MIG welding utilizes a welding gun with a machine-fed consumable wire. This metal wire serves as the electrode and provides the filler material for the weld at the same time.
While you work, the MIG welder delivers inert gas (usually argon) to shield the weld pool and protect the metal from contamination. The MIG welding gun automatically feeds more wire into the molten pool as you advance, so this option provides “what-you-see-is-what-you-get” welds that are easy to start, direct and control. (more…)
05 October, 21 1:55 pm ·Leave a comment·
Red-D-Arc Welderentals
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If you’re looking for a portable, hassle free, full-featured spool gun solution for your steel or aluminum welding projects, look no further than Lincoln’s Magnum PRO 250LX GT K3569-2 spool gun for you next in-field welding job. The Magnum PRO 250LX GT connects directly to Red-D-Arc’s new GX330XL (and Lincoln’s Ranger 330MPX) without the need for additional adapters or control boxes. It’s simply a matter of attaching the gas hose, attaching the 7-pin control cable, and attaching the power cable to the output studs for .025”, .035” steel wire welding or .030”-.035” and 3/64” aluminum wire welding. (more…)
How do I prevent wire feeding problems when using MIG welders (GMAW) or flux-cored arc welding (FCAW) processes?
Wire feed problems with a MIG welder can be caused by a variety of circumstances. Some of the most common reasons for wire feeding issues include:
Drive roll tension with the MIG Welder: The drive rolls that push or pull the wire through the system have a tension that is either too great or too little. Adjust the spring pressure until the tension is appropriate.
Drive roll size: The drive rolls may be the wrong size. For instance, if 1.3 mm drive rolls are being used to move 0.9 mm wire, slipping will most likely occur.
Drive roll type: Some wire requires specific kinds of grooves for optimal feeding. Flux-cored and metal-cored arc welding wires typically require V-groove drive rolls that are knurled. Aluminum wires require a smooth U-shaped groove.
Drive roll condition: Worn drive rolls will be ineffective at moving a wire through the MIG welder system.
Liner size: If a liner is too small for the wire it will not feed. If the liner is too big, the wire may have too much freedom to twist inside of it, causing an unpredictable feed.
Liner type: For most wires, steel liners work excellent. However, some wires, such as aluminum, require a nylon liner to help ensure proper feeding.
Liner condition: A worn liner will be detrimental to wire feeding. Replace the liner if it is worn or damaged.
Contact tip size: A proper contact tip size should be used. If the tip is too small, the wire will not feed; if the tip is too large, wire feeding and electrical conductivity may be negatively affected.
Wire condition: Not all wire manufacturers put out the same quality product. Some wires may have thin and thick spots as well as lubricants that can cause poor wire feeding.
Earlier this year, Red-D-Arc delivered several of our MIG/MAG 4-pak and 6-pak multi-operator welding packages to Heerema Fabrication (HFG) for their yards in Zwijndrecht and Flushing, Holland. HFG manufactures complex steel structures for use in the offshore oil and gas industry.
In addition to maintaining high-quality welding standards, HFG was able to increase both worker productivity and safety by employing Red-D-Arc’s multi-operator packs for the welding processes at their fabrication yards. The packs include six welding power sources and wire feeders with gas lines to accommodate up to six individual welders – and each welder has his own 115VAC power supply as well as an airline that provides filtered breathing air to the welder’s helmet. All input power, shielding-gas and breathing-air connections are made via single connections in the pak’s enclosure in order to simplify hook up as well as enhance portability.
“With the multi-packs our operators can get set up faster and start welding immediately. The time savings and increased efficiency easily covers the cost of the packs.”
After receiving their initial order of 6-paks, HFG placed a second order for 4-paks, having recognized the benefits of the system.
Red-D-Arc 4-Pak and 6-Pak MIG/MAG Multi-Operator Welding Packages are available for rent, lease or purchase. Contact Sales to learn more.
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