MIG welding is not a one-size-fits-all process. There are so-called “all around” MIG welders, sure, but there are times when it’s best to use a specific type of welder for specific situations and environments, not to mention a specific skill-set.
MIG welding is not rocket science, but that doesn’t mean you can just wing it and hope you can good results. If you want to do it right, you need to use the proper welding tools and execute the right techniques.
Speaking of proper MIG welding tools, there are two types of MIG welders, namely Gas MIG Welder (also called “Gas shielded welder”) and Gasless MIG welder (also called “Self-shielded Welder”).
Gas vs. Gasless MIG Welders: What are their differences?
One major difference between the two is that gas MIG welders use an external shielding gas while a gasless MIG welder doesn’t. A shielding gas is used to protect the welding material from contamination and oxidation caused by exposure to the atmosphere. There are many ways for MIG welders to generate a shielding gas, but mostly use a gas cylinder to pull it off. Let’s take a closer look at the craft of MIG welding without gas!
The gasless MIG welder, on the other hand, uses a self-shielding MIG wire (also called “Innershield wires”), a metallic tube filled with flux core. Once heated, this wire causes the flux to melt, producing a “gas shield” that will then prevent the welding material from being oxidized and contaminated. The melted flux also produces a protective slag that integrates alloys into the weld metal, which produces its mechanical properties.
(Note: It bears noting that gasless MIG welders are not really “gasless.” People have started calling them “gasless” because self-shielding MIG wires don’t need a cylinder of gas. With that said, we’re still going to use the term for the sake of those who prefer to use the term.)
Self-shielding MIG wires have other benefits besides protecting welds from oxidation and contamination. They also generate an intense arc that can be used on steel, specifically those thinner than 1.2 mm.
Another major difference between gas MIG welders and gasless ones are their polarity settings. “With shielding” gas MIG welding uses a single positive torch feed while gasless MIG welding uses a negative torch feed. However, in cases where the trigger is what drives the relay, polarity won’t matter at all. That said, some MIG welders can operate both with gas or “without gas,” and thus provide users the option to change the polarity of the torch based on the needs of the MIG welding job. Of course, MIG welders that can use both modes are more expensive, and that’s not even counting the upgrade kit that’s always required for “with gas” applications.
Gasless MIG Welders Considerations
Gasless MIG welding is becoming popular in industrial settings for many good reasons. For one thing, using self-shielded MIG welders means that companies don’t have to rely on shielding gas anymore, helping them save up on costs, not to mention help them do away with storage issues at the jobsite.
Moreover, using gasless MIG welders eliminates the expenses that would have otherwise been spent on tents or wind shields that are typically used to protect welds from the atmosphere.
Companies whose employees are used to stick welding, however, have to conduct the necessary training to help them properly employ the techniques used in gasless MIG welding and attune themselves better to the process. It also bears noting that the guns used for self-shielded MIG welders are also different from those used in stick welding, and as such require you to weld at different angles and postures. If the techniques aren’t executed properly, slag is likely produced. That’s why it’s important that you constantly check for the presence of spatter and debris in between passes. If you don’t, your wire feeding will be compromised, resulting in poor welds.
When doing gas MIG welding, it’s ideal that you begin with the electrode far away from the weld, and then allowing it to inch closer as the rod melts slowly during the welding process. It’s different with gasless MIG welding, in which you have to maintain the same position throughout the process. In this scenario, the recommended distance between the contact top to the weld is at least a half inch.
Pros and Cons of Gasless MIG Welding
Now that you know their differences (and similarities), you’re probably wondering which MIG welder to use. To help you arrive at an informed decision, let’s go over the pros and cons of each MIG welder type.
Here are the advantages of using a gasless MIG welder.
It’s more convenient
When picking a welder, it only follows that you pick the one that is most convenient to use. In terms of convenience, the gasless MIG welder has the advantage over the gas MIG welder. Firstly, gasless MIG welders are much more compact and lightweight, making them easy to carry. It doesn’t hurt that you don’t need to clean the welding material prior to welding.
Moreover, self-shielded flux-cored wire is better suited for welding surfaces that are rusted or painted over. Why? Because the flux used in such welders allow the tool to weld through rust and paint easily. It’s for this reason why gasless MIG welders are becoming the tools of choice in industrial settings.
It’s great for welding outdoors
You might want to go for the gasless MIG welder if the bulk of your welding jobs will be done outdoors. Why is it better than “with gas” MIG welders? Firstly, gas welders use a shielded gas, which tends to lose gas easily when exposed to windy weather. This causes the bead to become porous, which can compromise the quality of the weld. With self-shielded MIG welders, you can weld to your heart’s content in windy weather and not have to worry about your welding material getting contaminated or oxidized. If you’re a welder who’s always on the move, using a gasless MIG welder is the way to go.
It’s got better arc control
Gasless MIG welders, if paired with voltage sensing wire feeders, can give you increased control of the welding arc, allowing for cleaner, smoother, and more precise welds. Given the proper filling materials, MIG welding that uses self-shielded flux-cored wire can be an “all-position” method.
It’s easier to use
Training with gasless MIG welding is relatively easy. Because you don’t have to rely on high-strength pipes, you don’t have to keep monitoring a wide range of welding parameters.
Welding is faster
Unlike with stick electrodes used in gas mig welding, gasless welding has much greater deposition efficiency, which means less filler material needed to complete the job. If speed is of the essence (and given that you can maintain the quality), using a gasless MIG welder can help you get the job done in less time.
There are also some disadvantages to using a gasless MIG welder. If any of these disadvantages are a deal breaker for you, then you’re better off using another type of MIG welder.
Positioning is limited
To do gasless MIG welding right, you are relegated to limited positions. This makes welding overhead or vertically very challenging. While welding at these positions can be done, it takes some getting used to.
Production of fumes
Gasless MIG welders don’t have flux coating that can cause the welding material to solidify faster. In other words, they don’t have a covering that holds the molten pool, which is important when you’re welding at an overhead or a vertical position. As a result, toxic fumes are more likely to escape, which can compromise your health upon exposure. No surprise there. After all, welding fumes contain Argon, nitrogen, carbon monoxide,carbon dioxide, and hydrogen fluoride. According to OSHA, short-term exposure can result in nausea, dizziness, eye irritation, and kidney damage. Long-term exposure to such fumes can also result in cancer.
Switching to Gasless MIG Welding? Mull on these
Have you decided to switch to self-shielded MIG welding? Great! But not too fast. While switching to gasless MIG welding is often a good choice, there are specific considerations you need to think over and measures you need to take to ensure that the transition goes smoothly. Here they are.
Compliance to welding codes
Before you switch to gasless MIG welding, you need to be aware of the structural welding codes by the D1 committee of the American Welding Society (AWS). More importantly, you need to make sure that you’re complying with those codes.
Furthermore, you need to check if there are additional certifications you need to complete for specific welding tasks. If you already have certifications, it’s important that you get them requalified with the new welding procedures in mind. With that said, it’s ideal that you undergo requalification on a regular basis to ensure that the process is fast and efficient.
Choosing the right equipment
Choosing the right flux core welder or the best MIG welder is critical to gasless MIG welding. Considering that self-shielded FCAW requires a constant-voltage power source, you need to maintain the recommended voltage throughout the welding process. If your equipment isn’t able to maintain a steady voltage, welding mistakes or irregularities (porosity for instance) are to be expected.
Selecting the correct wire
For self-shielding welding to work, you need to use the correct wire, particularly the self-shielded flux-cored wire. MIG welding has different seismic requirements and requires the appropriate strengths, not to mention that the wire you’re using needs to have the chemical and mechanical properties that can accommodate the structural applications required for the welding job.
Best practices in Gasless MIG Welding
While gasless MIG welding is easier than most welding processes, it has its attendant challenges that need to be addressed. Here are the key practices that will bolster your success in self-shielded flux-cored welding.
Maintain the right travel speed and angle
When performing gasless MIG welding in the vertical position, aim your gun at an angle of 5 to 15 degrees. When welding in a flat or horizontal position, make sure that the drag angle is 15 to 40 degrees. Maintain your speed as slowing down can cause the piece to puddle, which can result in the production of slag.
Maintain correct heat input
You need to maintain proper heat input to ensure that the metals fuse well.To pull this off, use the voltage recommended by the manufacturer relative to the wire diameter. Slag inclusions are likely to occur if you don’t provide enough heat.
Clean the welding material thoroughly in between passes
By cleaning the surface of the base metal thoroughly between passes, you can remove contaminants that may cause fusion issues. You can remove any slag by using a chipping hammer or a wire brush.
Maintain the right penetration
Maintain the right penetration by monitoring closely much weld metal is being deposited to the joint within a given time period. You need to ensure that there’s enough space between the weld bead and the weld joint for the weld metal, especially when you’re making root passes and maneuvering through wide openings.
If you go too deep, the weld metal will penetrate through the base metal and hang from the underside of the weld. To prevent excessive penetration, reduce the voltage range to the recommended settings and slow down the wire feeding. If it’s the other way around (lack of penetration), turn up the wire feed speed and increase the voltage range. It’s also a good idea to set up the joint so as to make the groove’s bottom more accessible without losing your hold on the welding wire extension and the arc.
Prevent porosity and wormtracking
Porosity in weld metal is not pretty too look at, and you’d do well to do the proper measures to minimize it. One good way to prevent porosity is to use filler meals that contain deoxidizers. Also, double check that the wire stick-out (the wire’s extension length from the gun’s nozzle) is not 1.¼ inch apart from the contact tip.
Another common issue with MIG welding is the incidence of wormtracking, which are marks made on the weld bead’s surface due to the fumes released by the wire once the flux has melted off. You can prevent this from happening by maintaining the recommended voltage settings for the wire feed. If you spot signs of wormtracking, the best course of action is to turn down the voltage by increments of 12 volts until the issue is fixed.