Pulsed MIG Welding Tips And Techniques

Table of Contents > 1. What Is Pulsed Welding? 2. What Is Pulsed MIG Welding And How Does It Work?     2.1 MIG Pulse Settings     2.2 Pulsed MIG Vs Other MIG Transfer Methods     2.3 Double Pulsed MIG (Pulse-on-pulse MIG) 3. Advantages Of Pulsed MIG Welding     3.1 Pulsed MIG Welding Equipment Tips     3.2 Pulsed MIG Welding Technique Tips 4. Conclusion 5. 🧐Pulsed MIG Welding Tips And Techniques FAQ

MIG welding is one of the most popular welding techniques among beginners and new welders due to its low skill requirements, low costs, and satisfying results. However, we are seeing technological improvements that bring out the best of MIG, increasing the weld quality, welding speed, and appearance. 

These improvements are possible by introducing pulsed options as a completely new transfer mode to MIG welding, which provides better arc control, lower heat, low spatter, and better weld aesthetics. If you are wondering how - we will discuss pulsed MIG welding tips and techniques for the best MIG results.

Pulsed MIG Welding Process

What Is Pulsed Welding?

Unlike constant voltage (CV) welding, in which the current is represented by a straight line, the current in pulsed welding oscillates between the high and low ends. The high end, or the peak amperage, is the initial current you selected on your welder, and it melts the pieces and filler metal (electrode or filler wire) and fuses them.

Next, the current goes to a lower end, or background amps, which cool down the pieces, lowering the spatter and heat input and allowing better control over the weld puddle. These background amps are high enough to maintain the arc, but the metal transfer does not occur.

Pulsed welding is primarily used in TIG welding, providing even better heat control when welding thin and delicate metals. However, we are seeing increased use in MIG welding, allowing welders to produce TIG-like results, so let's explore it more.

What Is Pulsed MIG Welding And How Does It Work?

In MIG welding (Gas Metal Arc Welding) pulse is a modification of spray transfer mode. This non-contact transfer method provides high-speed manipulation of the electrical output of the welding machine, producing less spatter, lower heat input, better arc control, and better weld appearance compared to other transfer methods. 

So, how does pulsed MIG welding work?

In MIG welding, the peak amperage (high amperage) produces just enough heat to pinch a single droplet of the molten wire per pulse. The heat is then used to transfer the molten metal drop through the arc and feed into the weld joint.

When the heat is not needed, the current moves to background amps. The heat is not high enough to form drops, so the metal transfer does not occur. However, the current is high enough to maintain the arc and stop it from extinguishing.

Source: https://www.weldclass.com.au/blog/94-what-is-a-pulse-mig-a-how-why-guide-to-pulse-mig-welding

You might be wondering why this is beneficial. Well, it is simple: the lower heat allows the weld joint to cool off, which prevents burn-through and spatter. This heat control is crucial when welding delicate and thin metals, allowing you to control distortion and run at lower wire feed speeds.

MIG Pulse Settings

The first pulsed MIG welding machines were developed in the 1980s, but they were rather complex units requiring much skill to set up and control. Welders had to manually adjust the voltage and wire feed speed to match the pulse, leading to many errors.

However, this has changed today, as machines with synergic pulse options are much easier to use. Synergic pulse operation adjusts the waveshape and frequency automatically according to the inputted wire feed speed, and you can also find that in the YesWelder Firstess DP200 Dual Pulse welder.

 YesWelder Firstess DP200 Dual Pulse Welder

These synergic pulse MIG options made machines more beginner-friendly and widely used in hobby and DIY MIG welding. Nevertheless, there are industrial machines that still allow welders to adjust the following properties of the pulse manually:

• Peak/Base Amps: The primary current that you select on your welder is the peak or base amperage. This current melts the MIG wire and transfers it through the arc into the welding joint.
• Background Amps: Background or secondary amperage is the lower end used to cool off the joint, but the metal transfer does not occur. Welders usually show the background amps as a percentage of the primary current.
• Frequency (Hz): Frequency in pulsed welding shows the number of pulses per second, expressed in Hertz (Hz). For example, 1 Hz means the current oscillates from base amps to background amps once a second. The frequency in modern welders ranges from 0.5-200 Hz, but it can reach 500 Hz in industrial welders.

• Pulse Balance: The balance setting adjusts the length of each pulse. The default setting of 50% means that the current spends equal time in peak and background amps. However, advanced machines allow you to increase this percentage, meaning the main pulse will be longer and the secondary pulse will be shorter.

While these settings are standard in TIG welding, they are only found in high-end and industrial pulsed MIG welders designed for highly skilled operators who like to fine-tune their welds. However, as a beginner welder or welding enthusiast, you can use synergic pulse MIG welders, as they will do the hard part of setting everything up for you.

Pulsed MIG Vs Other MIG Transfer Methods

In the past, MIG welding used three primary transfer methods to transfer the molten filler wire across the arc: short circuit, globular, and spray transfer.

• Short Circuit Transfer: In short circuit transfer, the wire touches the workpiece and shorts to itself. This creates a small, quick, solidifying puddle, allowing welders to weld various metal thicknesses in different positions, but at the cost of limited wire feed speed, deposition rates, and risk of cold lapping.
• Globular Transfer: The globular transfer is a fundamentally uncontrolled short circuit that deals with most of its drawbacks. Globular transfer is much hotter than a short circuit, and large droplets of molten wire give better penetration and higher wire feed speed. This also has drawbacks, as globular transfer can produce high amounts of spatter and is limited to flat and horizontal fillet welds.
• Spray Transfer: The spray transfer uses a pure CV source that produces enough current to spray the molten wire into the welding joint. This results in high welding speeds, high deposition rates, good penetration, and strong fusion with minor spatter. However, as it requires a high current for transfer to work, it can cause burn-through in thin pieces.

Soon enough, pulsed MIG welding transfer emerged to address the drawbacks of each transfer method. So, what are the differences?

• Compared to short-circuit transfer, pulsed MIG transfer is also suitable for all positions, but it eliminates the risk of cold lapping and provides higher wire feed speed and deposition rates.
• Compared to globular transfer, pulsed MIG also produces good penetration and high wire feed speed, but it is not limited to any welding position, and it creates significantly less spatter. 
• Finally, as a modification of spray transfer, pulsed MIG produces high speed, high deposition rates, and fusion. Still, the background amps provide better heat control, eliminating the risk of burn-through on thin materials.

Dual Pulse MIG (Pulse-on-pulse MIG)

Even though pulsed MIG transfer has various advantages that make it highly valuable in many applications, inventors went further and introduced a dual pulse MIG or pulse-on-pulse MIG. In this process, the first pulse is your standard pulse with a peak and base amp. The second pulse turns the first pulse on and off.

Turning the initial pulse transfer on and off produces even more downtime between the high amperage moments. This allows even better heat control and makes the signature weld bead appearance known as a dime. As a result, double pulse MIG will allow you to produce those stacked dimes welds, which is something you only see with TIG welding.

Dual Pulse MIG Welds

Although MIG welding produces solid, clean welds, a double pulse can achieve good-looking, shiny, and clean welds, especially on aluminum. If you MIG weld aluminum often, consider the dual pulse MIG welder.

Advantages Of Pulsed MIG Welding

Lower heat input: By switching to a background amp, pulsed MIG transfer significantly reduces the heat input, which is crucial when welding thin or delicate metals. Spray transfer lacks heat control, so eliminating the risk of distortion or burn-through with pulsed MIG means fewer costs on ruined metal pieces. 

Reduced Spatter: Pulsed MIG welding can use a wide range of wire feed speeds without entering the uncontrolled short-circuit or globular transfer. Globular transfer, while hot and fast, struggles with lots of spatter that requires more time post-weld grinding and cleanup. Pulsed MIG, therefore, reaches good deposition and welding speed without the cost of spatter flying around and sticking to the base metal.

All-position, Fast Welding: High welding speeds are usually related to lots of molten metal that takes time to solidify or spats around the workshop. This usually limits the applications to flat and horizontal positions, where molten metal sits in the welding joint. Meanwhile, pulsed MIG with its cooling intervals provides faster weld puddle solidification, similar to short-circuit, which allows you to use it in any welding position, including vertical or overhead, without a risk of molten metal dripping from the joint.

Suitable For Beginners And Skilled Welders: Advancement in pulsed MIG technology brought out synergic machines that automatically adjust the voltage, frequency, and pulse length according to base amps, making this process highly beginner-friendly. However, industrial and high-end machines provide welders with waveform control, allowing them to fine-tune each parameter to the given application, preferences, and needs.

In advanced Dual Pulse MIG mode, the parameters can be adjusted.

Improved Productivity: Pulsed MIG welding is a fast metal transfer method with high deposition rates, good arc control, and adaptive machines, which is crucial in increasing productivity and cutting costs. Synergic machines make weld preparation faster, while good weld aesthetics and less spatter cut the post-weld cleaning and rework costs.

Aesthetic Welds: Pulsed MIG can produce highly aesthetically clean welds due to excellent heat and arc control. By adding an additional pulse to it, you can even get TIG-like results on aluminum, but with much lower skill requirement and complexity compared to TIG.

Pulsed MIG Welding Equipment Tips

Now that you understand the fundamentals, applications, and advantages of pulsed MIG, it is time for some tips and tricks that will help you choose the right equipment and make the most of it. Since it is still a technology in development, a single mistake can render it useless, so let's see how to overcome those issues.

• Reduce cable length to minimize inductance: As a rule of thumb, don't use cables longer than 50 ft with a pulsed MIG transfer. Coiling, big loops, or looping around conductive objects can create inductance that flattens the pulses, reducing their effectiveness.
• Provide good ground: MIG welding with higher pulse settings requires an excellent electrical path. That's why you ensure your ground is durable and well connected to a base piece.
• Check the connections: Before welding, always check the connections. All grounding and connections should be tight and secure, with clean clamps to the worktable or fixturing.

Before welding, always check the connections.

Pulsed MIG Welding Technique Tips

Besides the equipment, there are specific things about the technique you should consider before using the pulsed MIG welding. There are many similarities to a spray transfer variant, but there are still some that you should consider.

• Choose the suitable shielding gas: Pulsed MIG welding typically requires at least 80% argon shielding. Therefore, pulsed MIG welding carbon steels require 80-90%, and welders often mix it with 10-20% Carbon dioxide (CO2). Pulsed MIG welding aluminum requires inert shielding, typically 100% argon or a mixture of argon and helium. Pulsed MIG welding on stainless steel is generally carried out with 98% Argon and 2% CO2. 
• Watch For Travel And Work Angle: Like regular MIG, pulsed MIG welding requires a 45-degree work angle and a 10 to 15-degree travel angle. Most welders recommend pushing with pulsed MIG while short-circuiting is better with pulling (drag technique).

• Limit The Stickout: Similar to spray transfer, pulsed MIG transfer requires a stickout of 5/8 to 3/4 inch. Too long or too short stick-outs will affect the weld quality and appearance.
• Adjust Arc Length: You must adjust the arc length as you travel in welding, and that also includes pulsed MIG welding. While consistency is crucial, increasing the length will create less shorting while decreasing the length produces a tighter arc and increases puddle control. You don't want to be extreme, as a too-short arc will be very 'crackly' and create a lot of spatter, while a too-long arc can create black welds and cause porosity.

The Basics of Arc Length
Source: https://www.megmeet-welding.com/en/news/How-Does-Arc-Length-Affect-a-Weld

• Advanced Synergic Machines: If you are just learning how to weld and have started with pulsed MIG welding, you could look for advanced Synergic machines. Besides matching the pulse settings to the inputted current, these sophisticated machines can sense and adapt to variations in stickout, voltage drops, gap, or torch angle, making welding much more accessible for new welders.

Conclusion

Pulsed MIG welding truly is a complex but very beneficial technology that deals with most of the drawbacks of the other transfer methods. Its ability to control heat makes welding delicate and exotic metals much more manageable.

Additionally, high welding speeds, high deposition, and better wire consumption efficiency increase productivity and cut costs. Many desire less spatter, clean and aesthetically pleasing welds, which are easily obtained using an MIG welder with a pulse transfer mode.

The best part is that you don't have to spend a fortune on pulsed MIG welders as long as you choose YesWelder machines as your companions on a fascinating journey of welding.

 

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