This article is an amalgamation of two articles originally from the Fabricator: Aluminum GMAW: Winning the battle with wire feed & The difficulties of aluminum MIG wire feeding in welding
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From automotive manufacturing to shipbuilding and trailer fabrication, aluminum continues to be an increasingly popular material due mainly to its high strength-to-weight ratio and its corrosion resistance. The material allows these industries to produce products that weigh less but are capable of withstanding demanding use. For automotive applications specifically, aluminum helps provide emission improvements and fuel savings in new vehicles.
Despite its benefits, aluminum can be challenging to weld. Because of its inherent oxide, high thermal conductivity, and fast cooling rate, it requires better cleaning methods and slightly different welding techniques than steel to achieve a sound weld.
The welding wire also poses potential issues, as it is much softer than steel wire and can be easily deformed or crushed. In gas metal arc welding (GMAW) applications, that means the chance for wire feeding problems is greater. This is particularly true when welding with the series wires like , , and . These wires offer the advantage of better WELDABILITY and bead appearance, but are more prone to feeding problems within the welding gun liner since they have less columnar strength than other aluminum alloys or steel wires.
Five simple steps can help you minimize wire feeding problems and the downtime associated with them.
The first piece of the puzzle is the wire itself, including the spool or drum. The goal is to have a GMAW system that feeds wire continuously without interruption. If not, your day just got much longer, management is unhappy with the lack of production, and someone is probably spending valuable time on the with the wire supplier because “it’s always the wire!”
Choose Quality Wire. The quality of the aluminum wire you purchase, and use can have an effect on its feedability. Look for high-quality wire with a smooth finish and a consistent cast and helix to it, which helps it feed more smoothly. Lower-quality wire could potentially exit the contact tip in a wavy motion that produces an erratic arc.
Follow Proper Handling Techniques. Assuming the wire is manufactured and packaged properly, mishandling can be the root cause of your feeding problems.
It is important to handle the spool of wire properly. Always lift a spool from the bottom or at the center. Never lift a spool in a way that allows the flanges to flex away from the wire, as this can disrupt the precision-wound layers of wire. Take care not to disrupt the manner in which the wire is wound on the spool, either by dropping it or otherwise adjusting it. If you are using drum packaging, make sure they always remain vertical and that the wire is properly secured before they are moved.
Aluminum wire spools are level-layer-wound to ensure consistent wire feeding. Any bends in the spool or flanges could cause the wire to snag or hang up, which can lead to feeding issues during welding.
Set the Spool Brake Tension Correctly. Another consideration is the brake tension of the spool spindle. The brake should be set just tightly enough so that the spool does not spin freely when the feeder stops pulling the wire. If it’s too tight, the drive rolls may start slipping, which will typically cause the drive roll grooves to build up with aluminum. If the brake is too loose, the spool may continue to turn and the wire can jump over the spool flange, which will generally cause a tangle. The spool should have enough tension to prevent it from overspooling when you stop welding, but not so much that the spool can’t turn easily.
On most wire feeders, the wire will rub on some sort of inlet guide before it reaches the drive rolls. Although most inlet guides are plastic, this is a component that you need to inspect to ensure it is not metallic or grooved from the wire rubbing on it. This also applies to any guide that may contact the wire. Center guides (if present) and outlet guides should be tapered with a contour matching the OD of the drive rolls to allow their ends to be as close to the rolls as possible. Use nonmetallic inlet and intermediate guides to prevent shaving of the aluminum wire.
When feeding aluminum, you must eliminate all areas where the wire is not supported or encapsulated. The soft aluminum wire will always take the path of least resistance, so the machine must be set up to ensure the wire has a clear and controlled path to the contact tip.
The most common setup issue with drive rolls is excessive pressure, which can cause the wire to become misshaped, leading to excessive burn-backs. Excessive pressure can also contribute to wire shavings, especially if the drive roll grooves are incorrect or misaligned.
So how much drive roll pressure should you use for aluminum? Unfortunately, there is no magic number as multiple variables are involved. The best way to set the drive roll pressure for aluminum is to simply start at the lowest setting and gradually increase the pressure if the wire seems to be slipping under normal operating conditions. The technique used for steel, whereby you feed the wire into an obstruction and increase the pressure until it curls the wire, is not usually recommended for aluminum. That much pressure will generally cause aluminum wire to deform. Also, since aluminum GMAW typically is performed using the spray-arc transfer mode, there should not be any significant resistance to the wire as it leaves the contact tip.
Incorrect drive-roll tension can lead to different problems, depending on whether you are feeding from a 1-lb. wire spool with a spool gun or feeding from a large drum of wire with a push/pull gun. Tension that’s too tight typically leads to birdnesting, since the drive rolls will try to push the wire through to the contact tip even if there is an obstruction, rather than letting them slip. If you are welding from a large drum of wire, too much drive-roll tension can also restrict the wire from rotating smoothly as it leaves the drum, which can lead to tangling in the drum.
The drive rolls must also have the correct groove geometry and be properly aligned. Aluminum welders have always been told to use only U-grooved drive rolls. While a couple of other options are out there, the U-groove is by far the most common. The U-groove drive rolls avoid crushing or deforming the aluminum welding wire. These feed the wire efficiently while keeping its round shape and preventing shaving that could clog up the liner. Once you make sure you have the correct drive roll groove size, you should also take a look at the quality and geometry of the grooves under magnification (10x is usually enough) to ensure the grooves are smooth.
It is not uncommon to see rough contact surfaces within the grooves or sharp edges where the groove meets the outer surface. If either of these features is not adequate, you can either try a different manufacturer’s roll or polish the ones you have. Any fine-grit polishing stone that will fit into the groove should do the trick. In fact, many companies have developed a routine of polishing all of their new drive rolls before they are made available to production.
Most wire feeders have “floating” drive rolls. This means they have a little bit of side-to-side movement, allowing the wire to basically guide the rolls into alignment. However, if anything becomes lodged between the drive roll and the face of the gear, the roll may not float anymore, and the edges of the wire grooves could deform or gouge the wire. A simple way to prevent this is to pull the rolls off with every one or two wire spool changes and make sure the rolls and gear face are clean.
One of the most common misconceptions is that a push/pull arc welding gun is required for aluminum GMAW. While using a push/pull setup will typically minimize feeding difficulties, it is not always required. Many believe the need for a push/pull gun is based on the gun length. However, the stiffness of aluminum wire can vary greatly depending on the alloy. For this reason, arbitrary gun lengths are not always practical.
Soft aluminum alloys such as 1XXX, 2XXX, and 4XXX have lower column strengths than hard alloys like 5XXX. For example, 0.047-inch-diameter typically can work in a 10- to 12-foot push-only system that is properly configured without any issues, but alloy in the same system may have problems feeding since it is much less rigid. No matter how long the gun may be, minimizing the bends and loops between the feeder and the contact tip will significantly improve overall feedability.
Regardless of what length or style of torch you choose, you should consider using a nonmetallic torch liner—Teflon®, nylon, and graphite are the most common options available. Some aluminum liners now have a metal outer coil with a nonmetallic sleeve. This makes them look very similar to steel liners, so be certain the inside diameter (ID) of the liner is correct for your application. Push/pull guns also incorporate a neck liner between the pull wheels in the gun and the diffuser. While these are often coiled metal liners, nonmetallic should also be considered here. Basically, the goal is to ensure nothing in the feeding system can scrape the wire and cause shavings that could plug the liner or back of the contact tip.
Knurled drive rolls can come into play in either the feeder cabinet or a push/pull system. Generally speaking, knurled drive rolls are not suitable for aluminum GMAW because they slightly cut into the wire, generating a significant amount of shavings that plug the liner and/or contact tip. Knurled rolls are often found in the gun on push/pull systems, but the welders who use them have decided to deal with the shavings in the short neck liner to gain a better grip on the wire. While a system that is properly set up and maintained shouldn’t need the added grip, many companies put them in the push/pull gun as an added measure to help avoid burnbacks and feeding inconsistencies.
If you decide to use a spool gun they can hold a 1-lb., 4-in. spool of welding wire, which works well for small applications that won’t require a lot of wire changeover. Even though these guns can be used with longer cables, because the spool is mounted on the gun itself, the wire needs to feed only a short distance—typically from 8 to 10 in. This helps to minimize some feeding problems.
Spool guns do have limitations, however. Their design can hinder access to tight areas, and spools have to be changed very frequently. The spool also adds weight to the gun, so you may find it heavy to weld with for long periods of time.
The last component is the contact tip. It is very important to buy contact tips, liners, and guides designed for aluminum wire. Consumable manufacturers offer aluminum-specific contact tips, which have smooth bores that are slightly larger for a given wire diameter than tips for steel wire. Since Aluminum wire has a higher coefficient of expansion as compared to steel, the larger inside diameter (ID) helps to accommodate the increase in diameter of the aluminum wire when it is heated. This also helps to prevent burnbacks.
For a variety of reasons, contact tips are often the cause of setup errors. The two problems most frequently discovered are oversized tips and poorly manufactured tips. A lot of manufacturers make aftermarket tips. While the tips may look the same on the outside, they may contain lower-quality alloys, have manufacturing defects, or have inconsistent bore diameters.
The inlet can be examined with the 10x eye loop to ensure no burrs are left from the chamfering tool. Since many shops don’t have precision pin sets available for checking the ID of the tips, a drill bit of the appropriate diameter can be used to make sure it’s close. Generally, the ID of the tip should be approximately 10 percent more than the wire diameter. You can also use a tip dressing/reconditioning kit to ensure the bore is smooth and the inlet is clean.
Original Articles:
Aluminum GMAW: Winning the battle with wire feed by Rob Krause from The Fabricator.com: https://www.thefabricator.com/thewelder/article/arcwelding/aluminum-gmaw-winning-the-battle-with-wire-feed
Many welders consider welding aluminum the most challenging task due to its unique properties. Aluminum is lightweight and strong, but even the slightest mistakes can cause burn-through or surface oxidation.
Luckily, techniques and equipment have dramatically improved today, so you can tackle aluminum welding projects much more easily. Due to its ease of use and satisfying results, many new welders and beginners prefer MIG welding aluminum.
That's why we compiled tips for MIG welding aluminum, with practical advice and precautions that can help you flawlessly execute aluminum welding projects.
MIG Welding Aluminum Ramp Photo by @vanthefabricator (TikTok)If you are a new or beginner welder, we recommend MIG welding aluminum due to its ease of use. MIG welding is a straightforward welding method, and with the correct set of tools and equipment, you can successfully weld aluminum.
Most seasoned welders, on the other hand, prefer TIG welding aluminum. TIG welding provides unmatched cleanliness and excellent heat control, which is crucial in aluminum welding applications. It also yields better weld aesthetics, but it has much higher skill requirements and requires more expensive equipment.
Source: https://www.youtube.com/watch?v=-oJ3BGIrGHQTherefore, unless you regularly weld aluminum and work on the highest-quality projects, you can get away with MIG welding. So, let's see what you need to know to successfully MIG weld aluminum.
Aluminum is one of the most challenging metals to weld. The challenges arise from the surface aluminum layer that forms once bare aluminum gets in contact with oxygen. The affinity for oxygen creates a protective layer that shields the base metal from oxidation.
However, this protective layer has a much higher melting point than base aluminum. Thus, if you try welding through it, you will burn through the base aluminum.
Source: https://www.gabrian.com/aluminum-corrosion-resistant/Additionally, aluminum has high thermal conductivity. The metal dissipates the heat, which, paired with a low melting point, creates another challenge. You will need enough heat to start and maintain the arc but not too much to burn through the base metal.
So, to successfully MIG weld aluminum, you should do the following:
Let's further explain each tip.
MIG Welding Aluminum Project Photo by @heather_hume (TikTok)Aluminum is all about cleanliness, so all the surfaces must be squeaky clean before welding. Start by removing the dust, dirt, paint, or oil and grease from the surface. You can use an old rag or damp cloth, but make sure it is clean.
Next, you should remove the surface oxide layer. As noted, the oxide layer has a much higher melting point than base aluminum, so welding through it can cause many issues and burn-through. You can remove the oxides with a stainless steel brush, either a hand wire brush or a cup wire brush.
Source: https://www.youtube.com/watch?v=smwB3pO-Lr0&t=992sIf you are using a hand brush, make sure you have a stainless steel brush you'll only use to clean aluminum pieces to avoid possible contamination. When using power tools, keep the RPMs and pressure low to reduce smearing the surface and causing contamination or oxidation.
After brushing the metal, you can wipe the surface with acetone or isopropyl alcohol. These substances will also remove some of the remaining oxides and impurities.
Keep in mind that aluminum has an affinity for oxygen, meaning it will reform the oxide layer if exposed for too long. Therefore, you shouldn't wait too long after cleaning. Align and tightly fit the pieces to be completely flush, and start welding.
Aluminum comes in sheets and plates, including different thicknesses and gauges. However, for home or DIY projects, you are likely to use aluminum sheets up to 1/4 inch thick. MIG welding is suitable for most thin and medium-thickness aluminum sheets.
Conversely, seasoned welders do not recommend using MIG to weld aluminum thinner than 14 gauge (.074 inch). To weld super-thin aluminum sheets, you should consider TIG welding, which provides better heat control and stability at low amps. Additionally, consider using a pulsed MIG welder to control the heat.
Photo by @jasonwhitcomb64 (TikTok)Welding thick, industrial-grade aluminum requires specialized high-amp welders. But if you need to MIG weld thick sections of aluminum at home, you can preheat the pieces at 200°F to battle the high thermal conductivity and use regular 250-amp power sources.
The company is the world’s best Aluminum Mig Welding Wire supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
Smooth wire feed is crucial for sound and high-quality MIG welds, but there is a catch with aluminum. Because the aluminum wire is softer than steel, it can tangle, kink, clog the liner, or cause birdnesting.
To provide smooth wire feed, you should use U-groove drive rollers and check the tension. The U-rollers have smoother lines than V-rolls, so they won't deform the wire as they feed it.
Source: https://www.youtube.com/watch?v=YzMNIsdNj48&t=s
Tension also plays an essential role in aluminum wire feed. The overall tension shouldn't be too low to let the wire unspool itself from the main drum, and it shouldn't be too high, as it will cause birdnesting. The wire feeding mechanism will try to push the wire through to the contact tip even if there is an obstruction.
Keep in mind that softer aluminum wire can clog the MIG gun and contact tip even though you have the correct tension or rollers. To deal with this issue, you should shorten the path between the spool and the gun or use a sturdier liner. We will talk about these two solutions further in the text.
Use Teflon liner for MIG Welding AluminumNearly 80% of all aluminum wire fillers sold worldwide are either ER or ER. So, when MIG welding, you are likely to use one of these two types, but there are some differences you should know before making a choice.
ER is a general-purpose aluminum MIG welding wire with silicon additions that lower the melting temperature and boost weld pool fluidity. Overall, ER is easier to use and provides a better appearance than . You can use it in most groove weld applications and with alloys that don't have high magnesium additions (, , , or most 5xxx aluminum alloys).
ER/1LB-0.8 1LB Spool .030" Magnesium Aluminum MIG Welding Wire
ER is another general-purpose aluminum wire, but it is stronger and more rigid than ER. It has magnesium additives for improved tensile strength and sheer strength, which makes it suitable for high-magnesium alloys (5xxx series) and fillet welds subjected to load and stress. Since is more rigid, it is easier to feed, but it yields a worse weld appearance than .
Base aluminum reacts with oxygen in the atmosphere to create aluminum oxide. Therefore, to protect the weld puddle from contamination, you will need high-purity, non-reactive (inert) shielding gas.
When MIG welding aluminum, always use 100% Argon shielding gas. Although MIG welding works well with CO2 mixtures or even pure CO2 as a shielding gas, you should never use CO2 in any percentage when welding aluminum. Even small doses of carbon dioxide can react with the molten puddle, cause contamination, and affect the corrosion resistance of the aluminum.
Gas flow rates of 20-30 CFH are suitable for most MIG welding applications. Use 20 cubic feet per hour if there is no draft or wind in the shop or garage, or increase it if there is a risk of poor coverage. Don't use too high gas flow, as it can create turbulence that sucks in the oxygen and cause contamination.
In MIG welding, the transfer mode denotes the way molten MIG wire is transferred across the arc and into the weld joint. There are four MIG transfer modes: short circuit, globular, spray, and pulsed transfer modes, with each running hotter (at higher amps and voltage).
Source: https://www.aedmetals.com/news/mig-welding-transfer-methods
To MIG weld aluminum, you should use the spray transfer mode or pulsed MIG. In spray transfer, the many tiny droplets with a diameter smaller than the welding wire are sprayed across the arc.
To achieve this transfer mode, you will need high current (wire feed speed or amperage) and high voltage. The high current breaks the wire into tiny droplets, and high voltage precisely sprays them into the weld joint.
Spray transfer is smooth, provides high efficiency and deposition rates, and works very well with aluminum. However, it requires high wire feed speed and voltage, so you shouldn't use it on aluminum thinner than 14 ga.
MIG Welding Aluminum Source: https://www.youtube.com/watch?v=kCgm3bVDsMwOnce the aluminum gets thinner than 14 ga, you have two alternatives. Either go for AC TIG aluminum welding, which provides excellent heat control for thin aluminum or opt for a pulsed MIG power source. If you are an absolute beginner, we surely recommend pulsed MIG, as it is much easier to perform than AC TIG.
Pulsed MIG is a relatively new technology that provides better heat control, which is essential when welding delicate metals such as aluminum. In the pulsed MIG, the current oscillates between the peak amps and background amps.
Source: https://www.youtube.com/watch?v=ybRi2-lJNkIDuring the peak amps, the current is high enough to pinch the droplets of molten wire and transfer them across the arc. During the background amps, the current is lower, so metal transfer does not occur, but the arc remains forth. This low current reduces the overall heat input into the Heat Affected Zone (HAZ), reducing the risk of burn-through, warping, or distortion of thin aluminum sheets.
Due to its advantages, the pulsed MIG is an excellent feature for aluminum welding and a must-have for thin and delicate aluminum welding. But it doesn't stop there. New welding machines include the dual-pulse feature.
In the dual pulse, another pulse is added to the primary pulse. The primary pulse switches the current from peak to background amps, while the secondary pulse turns the first pulse on and off. This feature provides even better heat control on thin and delicate aluminum and allows you to acquire that stacked dimes weld appearance.
As a result, your MIG welder can produce TIG-like welds on aluminum. If you don't want to spend a lot of money on these features, make sure you check out YesWelder DP200 Dual Pulse Aluminum MIG Welder.
Firstess DP200 Multi-Process DualPulse™ MIG Welder
In the wire feeding section of the article, we discussed a spool gun, push/pull gun, and graphene liner, but there is much more to discuss these two. Due to wire feeding issues with regular MIG welding equipment, a spool gun, or push/pull gun as many call it, became a must-have aluminum MIG welding equipment.
LBT150 150AMP Aluminum Welding Spool Gun
Unlike a regular MIG gun, the spool gun has its drive motor and spool hub. You mount the aluminum wire spool directly into the torch to reduce the path wire crosses from the spool to the weld and, therefore, reduce the risks of tangling or bird-nesting.
MIG Welding Aluminum Using a Spool Gun Photo by @yeswelder (TikTok)The short path and high feeding speed made the spool gun essential in any aluminum MIG welding. YesWelder MIG205 DS is a spool gun-compatible welder, so you can plug it in and weld aluminum with ease.
MIG-205DS-Pro Multi-Process MIG Aluminum Welder
If you are looking for a cheaper alternative to solving aluminum wire feeding issues, consider getting a graphene liner. The liner is a tube that guides the wire from the welder through leads and into the MIG gun tip. Its slick surface allows the softer aluminum filler metal to pass through without catching or kinking.
Graphene Aluminum MIG WeldingWire Feed Liner
Although a graphene liner doesn't provide the same feeding properties as a spool gun, it is significantly cheaper. In addition, most spool guns are limited to 1 lb spools, but with liner, you can feed the heaviest supported spools by your welder.
Pushing or pulling in MIG welding is a matter of preference, but most welders prefer to push. When it comes to MIG welding aluminum, push is almost always the better option.
Pushing the gun when MIG welding aluminum improves the shielding gas coverage. In MIG, you don't get the cleaning action that AC-TIG provides. Pushing directs the Argon shielding into the leading edge of the weld puddle, providing overall better shielding gas coverage and protection.
Pushing the gun when MIG welding. Photo by @perfectwelders (TikTok)If you pull the torch, your shielding gas coverage lags. Since aluminum readily picks up oxygen, you'll see porosity and contamination quickly.
Remember that spray transfer in MIG welding aluminum means you will be running hot and fast. To avoid the burn-through, increase the travel speed, especially on thin pieces. Avoid long, continuous welds when welding thin aluminum. Prolonged heat exposure on sheets can cause distortion and warping.
Use a 3/4" wire stick stickout when welding in spray transfer. A shorter stickout can burn your tip, and you can also recess the contact tip to avoid prolonged heat exposure and damage.
Source: https://www.youtube.com/watch?v=-GGHvnc545s&t=71sThe crater is a welding defect that appears once you prematurely finish the weld without letting the weld puddle appropriately fill the end of the joint. In MIG aluminum welding, the crater is extra susceptible to thermal shock and cold cracks.
Source: https://its-good-to-be-me.blogspot.com//08/weld-stops-starts.html
To address this issue, we recommend a MIG welder with a crater fill feature, such as the YesWelder DP200 Aluminum MIG welder. This feature reduces the end amps, allowing you to spend more time at the end of the weld.
The more time spent in the end, the more you will adequately fill the joint. Meanwhile, the lower amps will keep the puddle going without burning through the hole in your weld.
You can also fill the crater manually, but it requires a lot more skill than automated settings. One way to deal with this issue is to use the back-step method. In this method, you go back a few millimeters at the end of the weld to fill the puddle.
The other option is to use run-on and run-off plates. You attach the plates at the start and end of the joint. You start by welding from the run-on plate into the joint and onto the run-off plate. That way, you reduce the risk of a cold start and crater at the beginning and end of the weld.
Use run-on and run-off plates when MIG welding to prevent craters. Source: https://havitsteelstructure.com/steel-structure-welding-technology/Welding aluminum, indeed, is one of the most challenging tasks for most welders. However, you can make it a lot easier by turning to the semi-automated principle of MIG welding.
MIG welding aluminum is a straightforward way to weld aluminum for your home projects, but it still requires a lot of attention. To successfully MIG weld aluminum, make sure surfaces, environment, and fillers are clean.
Use equipment labeled or advertised for aluminum welding, such as U-groove rolls, aluminum wire, spool gun, etc. Finally, work on your technique. By combining preparation, equipment, and technique, you can successfully MIG weld aluminum every time.
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