Push or Pull: Which Is Correct for MIG Welding?

After exploring how to MIG weld, part of the challenge is that there were two different methods for accomplishing the same task. You can implement either push or pull procedures in MIG welding, and deciphering which one is correct piques curiosity. After attempting both, it is clear that it takes a while to figure out which is correct.

Push or pull, and which is correct for MIG welding, depends on the equipment, material, process, and personal choice. With slag, pull is the most suitable method. The push welding technique is ideal for deep penetration and when there is more area.

If you are a rookie to MIG welding and push and pull methods, you want to go in-depth to understand precisely what the difference is. Then, when you pull out your equipment, you will not have to wonder whether to push or pull. Read on to find out how push and pull vary and how you can apply each of them to your welding projects.

MIG Welding and the Great Push or Pull Debate

Deciding whether to push or pull in MIG welding and which is the “right” way has been something that professional welders have discussed and debated over since the beginning of the trade. It is one of those situations that does not necessarily have a proper answer. You have to determine which is ideal for you.

The primary goal is to get the best welds possible, regardless of technique. Knowing what is required to accomplish that is what you have to take into consideration. The factors that must be put into your equation include:

  • The type of welding equipment you are using and the level of performance it produces
  • The material that will be welded, including composition and strength (steel, aluminum, alloys, etc.)
  • Which welding process you plan on implementing – pulsed, droplet, or short-circuiting
  • How much surface area will be welded
  • How deep the weld has to be

Of course, there is also the issue of which one you are personally most comfortable with. Personal comfort matters a lot with anything, MIG welding included.

The truth is, regardless of what you are welding, you can push or pull it and finish the weld. However, you could be dealing with not having a clear line of sight, a weld that will not hold, and welds that are not all that nice looking. Arm yourself with this useful information, and then you can make the most educated decision specific to your project.

What Does Slag in Welding Mean?

One constituent that all welders consider when deciding whether to push or pull for the most reliable results is if there will be slag. Slag is a nonmetallic byproduct that forms to safeguard the weld pool from environmental oxidation and the welding arc. Many times, the slag is removed when the welding project is complete.

There is no additional power created by leaving the slag on the weld, and it does not protect the metal. It is merely a waste material that comes from the process. If an additional weld pass has to be made, the slag must be ground off or otherwise removed before you can do so successfully.

You can remove slag that has been created using:

  • Flame-cleaning
  • Wire brush
  • Blast cleaning
  • Grinding

In some cases, the slag will embed in the metal. Other times it will float to the top. Both result in imperfections of the weld. Pulling is most suited for avoiding slag inclusions because if you push it, you are essentially forcing it into the weld puddle. With the need to remove it eventually, you are only creating more work for yourself.

The Pull Method in MIG Welding

Defining pulling in MIG welding is straightforward as long as you can visualize what you are doing with your weld gun. When utilizing the pull method, you are placing your machine in front of the weld and then pulling the puddle back.

The main benefit of using the pull method when MIG welding is that it gives you the ability to see the bead as it is being formed for the weld.

Advantages and Disadvantages of Pulling in MIG Welding

You will produce an excellent bead for welding with the pull method, but there are pros and cons to using it. After identifying what they are, you can decide with more clarity which is preferred for the task in front of you.

Advantages include:

  • A deeper penetration for a stronger attachment to the base metal
  • Pulls both pieces of the base being welded together for a more durable finish

Disadvantages of pulling:

  • Grinding is often required to smooth over the weld
  • Creates a more rounded appearance that is not as aesthetically pleasing in terms of what a “perfect” weld should look like

When you are not worried about the final appearance of your weld and the strength is your top concern, pulling a weld is almost always the safer option.

The Push Method in MIG Welding

The push method of MIG welding is when you put the gun at the back of the puddle, and you push the weld pool forward to make the workable bead. This method does not get nearly as deep a weld.

While the weld is not as deep, it is more aesthetically pleasing, making it a great choice when appearance matters or when depth is not an issue. Below are the advantages and disadvantages to keep in mind.

Advantages and Disadvantages of Pushing in MIG Welding

Just like pulling in MIG welding, there are advantages and disadvantages to pushing in MIG welding. Starting with the benefits, pushing a weld will produce:

  • A flat, wide, smooth puddle
  • A weld that binds more firmly to the base metal
  • An aesthetically-pleasing weld

The disadvantages include:

  • The weld is not as deep, so it is not as powerful
  • Push welds tend to fail in high-stress conditions, which could cause loss of investment or even safety issues, depending on what you are welding.

Pushing a weld is what many trained welders use because it looks nicer and covers a larger area. Again, it will depend on how deep you want the weld to go and how strong it must be to hold up. If your metal material being welded will put in extreme pressure conditions, pushing may not be the most suitable choice.

Can You Push and Pull the Same Weld in MIG Welding?

There is no absolute situation for pulling or pushing in MIG welding. You have to incorporate all factors to determine which to use or if you can utilize both. 

Pushing a WeldPulling a WeldImplementing both techniques
Excellent for when welding a vertical down directionIdeal for welding things like I beams or when deep penetration is requiredUsed when welding a half-inch rod to a flat weld
Results a flat, smooth finishResults in superior structure and strengthStart on one side, pulling and push it back across the opposite side or vice versa

Practice makes perfect, and you have to use your creativity to determine which method is best for you. A good rule of thumb to remember is if you want a clean, good looking weld, you should push. If you want a strong, deep, reliable weld, pulling tends to be the way a professional would accomplish it.

Knowing Your Material Type in MIG Welding

Some of the most experienced MIG welders say that the strength and type of material you are welding has a significant impact on the decision between pushing or pulling your weld beads. If you were in a welding class, most teachers would tell you that aluminum should always be pushed while steel should be pulled.

Take a look at some of the most popular metals welded and familiarize yourself with each. It will help later on when working with different material types.


Types of Welding Materials
AdvantagesCompositionWelding ProcessNotesDisadvantages
SteelStrongIron and 2% other elements
High, medium, and low alloy
High carbon equals stronger steel
Used with any welding processClean welding areas firstRust and oxidation flaking
Stainless SteelHygienic and resistant to corrosion10% – 30% chromium with other elementsTIG, MIG, or Stick WeldingHigher cost
AluminumNot as corrosiveAlloys:ZincManganeseCopper/AluminumTIG, GMAW (Gas metal arc welding)Stick for smaller projects
CopperHigh heat and electrical conductivity
Resistant to corrosion
Wear-resistant
Appearance
99.3% copper content minimum
Alloys:Nickel silverHigh copper (5% alloy)Brass (copper-zinc)Copper-tinCopper-nickelSilicon bronzeAluminum bronze
TIG, GMAWCleaned with a wire brush and degreased before welding. Oxides must also be removed after welding
Cast IronHigher carbon and silicon contentOxyacetylene weldingSurface cleaned prior to welding to remove oil and grease. Cracks need to be filed or ground down.

Getting used to working with the different types of materials handled in welding will significantly help planning whether to push or pull. You decide what works for you, but knowing what the material is when starting the project will help cut out some of the guesswork.

Following the Proper MIG Welding Processes

In MIG welding or metal inert gas welding, you use a process that requires:

  • A MIG welding machine
  • A solid wire electrode
  • Shielding gas

The MIG welding gun sends the shielding gas through next to the wire electrode. The arc that comes out of the wire melts the workpiece to form the weld material pool that you will either push or pull into position before it hardens. The combination of shielding gas helps to protect the weld pool from being contaminated by airborne particles.

As part of deciding whether to push or pull, you have to determine what kind of MIG welding process you plan to utilize. For example, if you are welding a thin material, you will more likely use the short-circuiting process, and that is best combined with the better looking, not quite as intense, push method.

There are three primary processes for MIG welding.

Pulsed

In the pulsed MIG welding process, the power is switched back and forth between a low background current and a high peak current at a rate of 30 to 400 times every second. The higher peak current switch results in a droplet of the wire being pinched off and forced into the joint of the weld.

Pulsed MIG welding is excellent for beginner welders because it gives you the ability to learn how welding works and leaves a nice bead appearance. There is more control of the profile of the bead, and there are greater arc stopping and starting capabilities.

Droplet or Spray

Droplet or spray MIG welding involves a wire coating material, powder, or rod that is melted and forced towards the material. The consumable gets melted using a source of energy like:

  • Fuel
  • Ionized gas
  • Pressured gas
  • A mixture of gas oxygen and powder
  • Preheated gas

The spray process is superior when you need to coat the material at varying thicknesses. Other names for spray or droplet welding include flame and arc welding, plasma transferred arc welding, High-Velocity Oxygen Fuel (HVOF), detonation gun spraying, or cold spray.

Short-Circuiting or Dip

This method is mainly used when welding thinner sections or materials together. It is the lowest range of current, and the wire electrode contacts the weld pool 20 to 200 times each second.

Short-circuiting is also a useful process for positional welding when you have to be very precise.

Common MIG Welding Mistakes to Avoid

Even the most experienced MIG welders will tell you that mistakes happen. The only thing that you can do to perfect your skill is practice. The more time you spend welding, regardless of material type, process, and whether you push or pull, the better you will get, and the easier it will be.

With both pushing and pulling, you will find that errors tend to happen time and time again. You can avoid these right from the start by identifying what they are and how to watch for them.

Failing to Prepare Your Material

Regardless of what you are welding and what technique you use, it is vital that you properly clean the area you will be welding. If you skip over this essential step, you are more likely to see imperfections from contaminants.

Not only will your weld not look pleasing, but you will also have a weld that is not as strong as it could be. Make sure to grind off certain things, such as:

  • Rust
  • Dirt
  • Paint
  • Cracks

Grind until they are totally gone. If you do not, your material will continue to crack right along the same line.

Not Applying Enough Passes for Thicker Materials

Any material over 1/4″ thick is going to require more than one pass. Speeding up the current and moving more slowly is a mistake many make. Trying to do this will result in a less durable weld.

Ensure that you take your time and apply the right weld for the job at hand, making sure you do it right the first time to avoid future problems.

Implementing the Incorrect Technique for the Job

The technique goes back to push and pull for starters and includes the angle of your electrode, how fast you are working, and the length of the arc. If you are not familiar with what technique to use for the project, you are more likely to run across problems.

An example of this would be moving too slowly on a weld. If you are not traveling fast enough, you will get an excess pile of weld metal in the pool. Another example is if you are welding on a tight angle and try to pull instead of push, you could run out of room with the space constrictions.

Trying to Weld Worn-Out Metal

Take a close look at the metal you are expecting to weld. If it has been broken more than once, and the damage is in the same area, welding it might not be the right solution.

If you notice something wrong, you might have to reinforce the space being welded before trying and implementing any push or pull method.

Choosing the Proper Consumables & Taking Care of Your MIG Welding Machine

Different types of welding machines work better with various electrodes and wire choices. In MIG welding, a .035 S6 is an outstanding all-around solid wire. Other consumables you will have to purchase or have on hand to be fully prepared for interrupted MIG welding include:

  • Gun consumables, or the front end part of the gun
  • Nozzle
  • Retaining head
  • Contact tip
  • Liner

You must also take care of the wire and MIG welder while being stored to avoid rust formation. The devices should be left in dry spaces, and some must be kept in sealed containers. To prevent a fire, never place a hot welding gun on or near anything flammable.

Always talk with your supplier and check the manufacturer’s directions for details associated with your specific materials.

Survey the job you are MIG welding thoroughly before jumping in with your MIG welder. Take the time required to make sure that you have the steps laid out to arrange the most effective results.

Conclusion

The only time you get a definite answer on whether to push or pull in MIG welding is when you consider the space you have. For some projects, you will not be able to get your weld gun in the proper positioning to pull, and other times you can not fit it correctly to push. It is situational, and you have to evaluate that piece before starting.

There is no right or wrong answer. You have to input all the variables of equipment, process, material type, and what you are most comfortable with. That is when you will know whether push or pull is correct in your MIG welding job.

Sources:

https://www.weldingsuppliesfromioc.com/blog/push-or-pull-which-is-right/

https://galvanizeit.org/knowledgebase/article/weld-slag-clean-up-requirements-for-galvanizing#:~:text=Therefore%2C%20weld%20slag%20must%20be,deposit%20onto%20the%20weld%20area.

https://www.millerwelds.com/resources/article-library/pulsed-mig-welding-on-aluminum-the-details-and-advantages#:~:text=Pulsed%20MIG%20welding%20is%20a,it%20to%20the%20weld%20joint.

https://www.sciencedirect.com/topics/engineering/short-circuiting-transfer#:~:text=Short%20circuiting%20transfer%20occurs%20in,for%20bridging%20large%20root%20openings.

https://www.agriculture.com/machinery/tools/welding/5-most-common-welding-mistakes_245-ar22700

https://weldingheadquarters.com/what-is-slag-in-welding/

Alexander Berk

A bit about myself: I am a certified international welding engineer (IWE) who worked in different welding projects for TIG, MIG, MAG, and Resistance Spot welding. Most recently as a Process Engineer for Laser and TIG welding processes. To address some of the questions I frequently got asked or was wondering myself during my job, I started this blog. It has become a bit of a pet project, as I want to learn more about the details about welding. I sincerely hope it will help you to improve your welding results as much as it did improve mine.

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