Understanding Globular Transfer in MIG Welding

At its roots, MIG welding is a straightforward welding method prevalent among beginners, home welders, and hobby or DIY lovers. However, MIG welding today can do much more than home welding projects.

Like other methods, unlocking the full potential of MIG welding requires time, practice, and patience. One crucial step in mastering the art of MIG welding is becoming familiar with metal transfer modes. In this article, we will focus on globular MIG transfer.

Understanding globular transfer in MIG welding is essential in producing sound and high-quality MIG welds, so let's learn more about it.

Globular Transfer in MIG Welding
Source: https://www.youtube.com/watch?v=XkbgXQ7Wl-Y

What is the Metal Transfer Mode in MIG Welding?

If you are new to welding, or MIG in particular, you have likely heard the term metal transfer mode or MIG transfer. MIG transfer mode explains how the wire transfers across the arc and into the weld joint, but let's first explain the foundation of this process.

In MIG welding, the MIG wire serves as both filler metal and consumable electrode. The MIG gun with its wire is connected to the positive side of the cycle (EP), while the ground is negative (EN). Once you press the trigger, the wire becomes electrically live, and as it touches the negative base metal, it creates a welding arc that melts the pieces and wire.

Molten wire can transfer differently into the joint depending on the voltage and wire feed speed, or shielding gas. The voltage and amperage can pinch out droplets of wire, short-circuit itself, or spit into the weld joint. How the wire transfers into the joint can significantly impact productivity, appearance, or puddle control. So, achieving a suitable metal transfer for your welding project can be crucial.

What is the Metal Transfer Mode in MIG Welding
Source: https://www.researchgate.net/

Types of MIG Metal Transfer Modes

Depending on voltage, wire feed speed (amperage), or MIG welder settings, there are four MIG metal transfer modes:

• Short circuit transfer: This is the lowest current transfer mode. In this mode, the wire electrode touches the workpiece and creates a short circuit. Short-circuiting causes the wire to melt and transfer to the weld pool.

• Globular transfer: The molten metal forms large, irregular droplets that are transferred into the joint under the influence of gravity. The droplets are larger than the wire diameter, allowing you to fill the joint faster, but at the cost of excessive spatter.

• Spray transfer: This is the highest energy transfer in which the fine droplets of molten metal are continuously sprayed from the electrode to the workpiece. Spray transfer produces fast and clean welds, but occurs at high voltage and speed.

• Pulsed spray transfer: This is the advanced spray transfer in which welding power alternates between high and low current. Pulsed transfer is suitable for all positions, it provides excellent heat control but requires advanced equipment.

4 Types of MIG Metal Transfer Modes
Image credit: Mohamed Hamdy Abd El-Aziz (LinkedIn)

The first three transfer modes are considered base MIG transfers and primarily depend on the wire feed speed, voltage, and shielding gas. Therefore, entering one mode will require more or less heat or shielding gas, regardless of the welding machine.

Meanwhile, pulsed spray transfer requires proper welding equipment, so you'll need a pulsed MIG welder. Although often complex or expensive, machines such as YesWelder DP200 provide the best value and versatility for both beginners and professional welders.

Firstess DP200 Multi-Process MIG Welder

Quick Comparison of Three Base MIG Transfer Modes

Understanding the Globular MIG Transfer

The globular transfer is the medium-current transfer mode, which makes it widely popular among MIG welders across the globe. This transfer is positioned between low-current short-circuit transfer and high-current spray transfer, which makes it somewhat of a sweet spot for many MIG welding applications.

Instead of short-circuiting, the higher current melts the wire and forms large and irregular droplets or globs, ergo the name globular transfer. Meanwhile, the current is not high enough to cause the molten wire to further split into smaller droplets or spit into the joint.

Globular MIG Transfer
Source: https://www.youtube.com/watch?v=OljiaJc2kw8

The large droplets of molten wire transfer under the influence of gravity. This limits the applications of globular transfer to flat and horizontal positions. Globular transfer mode, also known as open arc welding, is done by a nonpulsed current source. 

What makes this metal transfer unique is the fact that droplets are larger than the base wire diameter, allowing you to quickly fill the joint. Most importantly, these large globs show excellent performance and penetration on medium-thickness and thick metal, but at the cost of high spatter and weld puddle control.

MIG Welding Globular Transfer Process
Source: https://www.youtube.com/watch?v=d3WxSxJ_LtA

Applications of Globular MIG Transfer

Due to its nature, the globular transfer MIG has ups and downs. Thus, understanding its applications is crucial in making an informed MIG welding choice.

The globular transfer MIG is best suited for:

• Medium to thick sections of steel or other metals

• Flat or horizontal fillet welds

• When you want to cut costs by using cheaper shielding gas

• Applications requiring higher deposition rates

• Structural steel or construction work

Let's explain why.

Globular Transfer MIG Welding Process
Source: https://www.youtube.com/watch?v=NQYI95PBiUY&t=18s

Globular Transfer and Thick Steel

Compared to short-circuit, globular transfer requires higher voltage and wire feed speed. Although the heat is not as high as spray transfer, experts recommend globular transfer on metals 1/8 in. (3 mm) or thicker.

Large droplets and higher heat that produce higher penetration don't work well with thin pieces. So, if you are looking for a metal transfer mode for thin steel, you should tune the parameters down to a short circuit. Nevertheless, globular transfer is your go-to choice if you are looking for a metal transfer for thicker steel and large joints.

Globular Transfer MIG Welding on Thicker Steel 
Source: https://www.youtube.com/watch?v=Xc1cfcRtk4w

Globular Transfer in Flat and Horizontal Positions

In globular transfer, the wire electrode is fed to deposit using arc forces and gravity across the arc in globules. Since gravity pulls the globs downwards, the globular transfer is best used in horizontal or flat welding positions. In these positions, gravity pulls and evenly distributes the weld metal across the joint.

Trying to use globular transfer in overhead or vertical welding positions can create various issues. Most importantly, you will struggle to control your puddle. The globs can slide down the joint or drip onto your welding helmet.

Globular Transfer in Horizontal Positions
Photo by @millerweldersofficial (TikTok)

Globular Transfer and Shielding Gas

One of the most significant advantages of globular transfer is its ability to work well with pure (100%) CO2 shielding gas. CO2 is a semi-inert shielding gas, meaning it only partially reacts with the base metal. However, it is considered generally safe in MIG welding, particularly on medium and thick carbon steel. There is also a variant of MIG welding that uses 100% CO2, known as MAG (Metal Active Gas) welding.

Many turn to CO2 and globular transfer with it in applications where you need to finish the job quickly and cheaply. CO2 is much cheaper than inert gases such as Argon or Helium, and it will get the job done, at the cost of a worse weld appearance and more spatter.

MIG Welding with 100% CO2
Source: https://www.youtube.com/watch?v=pTsithkxj8U&t=151s

High Deposition of Globular Transfer

The globular transfer involves creating large, irregular droplets with a diameter higher than the base diameter of the MIG wire. Using larger droplets can be highly useful when your projects involve filling larger gaps or welding thick joints.

Compared to a short circuit, globular transfer uses a higher current, which yields higher deposition rates. Combined with its ability to fill larger gaps, high deposition of globular transfer makes it ideal for these applications. However, keep in mind that globular is not faster than high-energy spray transfer.

Globular MIG Welding Process
Source: https://www.youtube.com/watch?v=X6rQ88JejlM

MIG Globular Transfer Welding Structural Steel

All the applications and advantages noted above make globular transfer a highly logical choice when MIG welding structural steel. Construction work often includes welding medium-thickness or thick structural steel in horizontal or flat positions.

The penetration of globular transfer and pure CO2 shielding works well on most structural steel welding. The increased penetration and deposition speed are advantageous, even if the weld requires more post-processing to remove the spatter.

Stainless steel MIG welds using the globular transfer process with C2 gas.
Source: https://gowelding.org/welding/mig-gmaw/transfer-types/

Limitations of Globular Transfer in MIG Welding

Although advantageous in many applications, globular transfer has limitations that can break your welding project if you are not careful enough. Most drawbacks are linked directly to the very nature of the globular transfer mode, so understanding them is crucial in making an informed choice.

The typical limitations of globular transfer in MIG welding are:

• Creates excessive spatter

• Poor weld appearance

• Limited to horizontal and flat positions

• Not suitable for all metal types and thicknesses

• Lack of control over the process

MIG Welding Globular Transfer 
Source: https://www.youtube.com/watch?v=Q_2-KZdU5n8

Globular Transfer - Spatter and Weld Appearance

While large droplets are good when filling larger gaps and joints, the transfer can be unpredictable and hard to control. The large globs often fall uncontrolled, causing a significant amount of spatter around the weld area.

Even though MIG welding produces some spatter at its base, excessive spatter can lead to poor weld appearance and additional cleanup after welding. Rework or post-welding cleaning increases the overall welding costs.

Due to the inconsistent droplet size and excessive spatter, globular transfer also affects the appearance. The produced weld bead is typically less smooth and aesthetically pleasing than other transfer modes like spray or pulsed-spray transfer. These disadvantages make globular transfer unsuitable for applications where the visual quality of the weld is crucial.

Spatter and Weld Bead Appearance in MIG Globular Transfer 
Source: https://www.youtube.com/watch?v=X6rQ88JejlM

Out-of-position Limitations

Globular transfer relies on gravity to transfer the large droplets to the weld pool. This mechanism makes it difficult to control in vertical or overhead positions.

As noted, using globular transfer in any position other than flat can cause highly inconsistent transfer and puddle control. The gravity displaces the molten metal from the joint, causing various defects, including a lack of fusion, improper penetration, or poor tie-in.

The solutions to the challenges of welding vertical or overhead include increasing the heat and welding speed to battle gravity. Nonetheless, as you increase the speed and heat, you reach spray transfer that is better suited for out-of-position welding.

Overhead MIG Welding with Pulse Spray Transfer
Source: https://www.youtube.com/watch?v=gxev0y16O2o&t=380s

Metal Thickness and Type Drawbacks of Globular Transfer

The high current (although not the highest) makes globular transfer best suited for metals thicker than 1/8". Higher penetration and heat can cause several defects in thinner metals, including burn-through, warping, or distortion. Large globs can overfill the joint, causing overheating and excessive reinforcement. So, you will want to tune the heat down and enter the short-circuit transfer.

An additional issue of globular transfer concerns its shielding gas choice. Since globular transfer works well with 100% CO2, this transfer mode is not ideal with non-ferrous or reactive metals such as aluminum or stainless steel. On both, the CO2 will affect the corrosion resistance, so the globular transfer is limited to carbon steel. If you are looking to weld aluminum, you will need pure argon shielding and pulsed-spray transfer for best results.

Pulse MIG Welding Aluminum 
Source: https://www.youtube.com/shorts/t7-UmzHhlhU

Lack of Control and Stability

The arc in globular transfer tends to be less stable and more challenging to control than in other transfer modes, especially spray transfer. The large globs are irregular and highly random, affecting your ability to control the deposition, penetration, or the weld's uniformity.

Firstly, inconsistent droplet transfer can make the weld quality less reliable, particularly regarding penetration and overall weld strength. Uneven penetration can weaken the joint and increase the risk of defects like a lack of fusion or incomplete fusion. Drawbacks are particularly notable on joints that require precise penetration control.

Poor arc stability can cause more frequent fluctuations in the weld pool. These fluctuations significantly increase the likelihood of welding defects. In addition, a lack of stability can create welds that are less smooth and aesthetically pleasing than other transfer modes like spray or pulsed-spray transfer.

Poor Arc Stability in Globular Transfer
Source: https://www.youtube.com/watch?v=Tq3ni6CNHF8

When is Globular Transfer the Best Choice?

All noted limitations and advantages make globular transfer less ideal for applications that require clean, precise, and visually appealing welds. Additionally, it is not a go-to choice for any out-of-position welding.

0It is mainly suited for situations where cost and material thickness are more critical than weld quality and appearance. Globular transfer is most suitable for flat-position welding on thick materials where high deposition rates and cost control (using CO2 gas) are important, but weld appearance and spatter control are secondary concerns.