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Frequently Asked Questions About MIG Welding

Metal Inert Gas, or MIG welding, is generally the easiest welding method to learn and use. Even so, it is not foolproof and trouble may occur if the operator is inexperienced with their equipment, technique, and maintenance. Here, we address some frequently asked questions from our customers. Find the answers to your MIG welding questions here.

 

Q: When should I change my contact tip?

A: If you experience a burnback that fuses the filler wire to the tip, if the tip develops a “keyhole” shape in the front, if it becomes bent or deformed, or if excessive spatter accumulates.

 

Q: What Is stickout?

A: Stickout, also called contact tip to work distance (CTWD), is the distance the wire must travel between the leading edge of the contact tip and the workpiece. A longer stickout increases amperage. A shorter stickout reduces it.

 

Q: What materials can I MIG weld?

A: You can MIG weld carbon steel, stainless steel, and aluminum with the proper equipment, shielding gas, and filler wire.

 

Q: What shielding gas should I use for MIG welding?

A: The most common shielding gas for MIG welding is 75/25, which is 75% Argon and 25% Co2. Other various mixtures of Argon and Co2 are often used as well as straight Co2 and occasionally Helium.

 

Q: What do I need to start MIG welding?

A: At a minimum, you’ll need a machine, filler wire, shielding gas, a regulator with hose, a torch, consumables, a work lead, a source of appropriate power for the machine, and personal protective equipment (PPE) such as a helmet and gloves.

 

Q: Do I have to use shielding gas?

A: No. If you do not have shielding gas or your machine is not equipped with a gas solenoid, you may use flux core wire, which is self-shielded. This process is called FCAW, or Flux-Cored Arc Welding.

 

Q: Should I push or pull my weld?

A: There is a lot of debate on this, however it is generally recommended to push your weld where possible unless you are using flux core or dual shield wire or where more penetration is needed.

 

Q: Should I use a protruding (stickout), flush, or recessed nozzle?

A: This is largely a user preference decision and will vary depending on the amount of spatter generated by your process, but as a general rule you should transition from a protruding nozzle to a recessed nozzle as you go up in amperage. The goal is to maintain a consistent CTWD while keeping the contact tip protected from spatter and heat.

 

Q: What is the difference between MIG guns and why should I upgrade?

A: There are many choices of MIG guns on the market. They differ in cost, length, size, duty cycle, amperage rating, design, and functionality. Upgrading your MIG gun can offer benefits such as increased durability, higher duty cycle, improved shielding gas flow, better ergonomics, easier access to the weld joint, and more.

 

Q: Is MIG welding better than TIG welding?

A: That’s a loaded question! Both processes have their advantages and disadvantages. See our blog article on why MIG welding is better than TIG welding HERE (https://americantorchtip.com/blog/why-mig-welding-is-better-than-tig-welding).

 

If you have further questions about MIG welding, feel free to reach out to us, or read more of our resources on MIG welding.

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Case Study: How this Midwestern railroad manufacturer achieved $260,000+ in annual savings by switching welding consumables

Located in the sprawling great plains of the Midwest, this reputable rail manufacturer operates three high-volume railcar manufacturing facilities across Missouri and Arizona. In operation since 1988, this manufacturer has grown to employ a large workforce of 1,600 hardworking welders specializing in the construction of hopper and tank cars.

However, the welders frequently reported experiencing technical difficulties with their equipment that was leading to significant downtime and eating into their overall output month-over-month. In efforts to increase corporate efficiencies, the manufacturer looked for a solution.

Read Full Case Study

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Basics of MIG Welding: MIG Gun Liners

Basics of MIG Welding: MIG Gun Liners

Have you ever encountered feeding problems in MIG Welding? MIG Gun Liners can help.
Oftentimes, feeding problems can be prevented with the right equipment maintenance.
Welding MIG Gun Liners
Welding problems are a mild inconvenience at their least. At their worst, they contribute substantially to lost productivity and cause delays in the fabrication process.
MIG gun liners tend to have some kind of mysterious aura surrounding them and even some veteran MIG welders don’t fully understand the design, function, and replacement process of their liners.
However, we’re here to simplify the use of MIG gun liners and provide you with a more in-depth understanding of their role.

What’s the Function of a MIG Gun Liner?

The basic function of a liner is to act as a guide for the wire electrode from the drive rolls to the contact tip. Sounds simple, right? Well, yes and no.
While the job of a liner is pretty straightforward, the dynamics of a MIG gun and wire feeding system present a unique set of challenges. When the wire encounters resistance on its journey from the spool to the pool, a myriad of problems may occur.
The most common symptoms of a wire feeding issue are erratic wire feeding, burn back, and bird nesting (this can occur at either end of the liner). Consequently, you should carefully choose liners to fit the application.
Most liners are manufactured from carbon steel wire (also called music wire or piano wire), which is tightly wound in a coil to allow for a balance of rigidity and flexibility. The profile of the wire can be round, oval-shaped, or flat, with each shape lending itself to the optimum function of its design.
Liners for use with stainless steel, flux-cored, or aluminum wire will often be coated with a polymer such as Teflon to reduce drag, wear, and contamination. Tightly fitted insulation wrapped around the base of the liner prevents shielding gas from seeping through where the gun cable exits the feeder. Additionally, the insulation is often bent at a more substantial angle as gravity pulls it downward.
Liners are typically sized to match both the diameter of the wire and the length of the gun cable. There is some margin of error on both accounts.
Typically, moving up one or two sizes on the diameter of a liner will not impede proper feeding (example: a .045” liner being used with .035” wire). The fit is more critical with smaller diameter wire than with larger sizes. A.023” wire may not feed properly through a .035” liner.
Where you are likely to run into problems is trying to squeeze a larger diameter wire through a liner that is not designed for it(such as .035” wire through a .030” liner).
Liners are typically a foot or so longer than the gun and cable assembly, which allows the operator to trim it to the proper length.

When should you change a MIG Gun Liner?

Liners don’t get the attention they deserve. They sit silent, ignored, and unmaintained until a problem happens. Truth be told, they don’t need a lot of attention, but a little bit of love goes a long way. The single most important measure a welder can take to prolong the service life of their liner is to keep contaminants out of it. This can be accomplished by keeping your wire feeder closed or off the floor and blowing out your liner with compressed air. It is generally recommended that the latter be done every time a new roll of wire is installed in the feeder. Simply remove all wire from the MIG gun, remove the contact tip, remove the MIG gun, and shoot a few blasts of clean compressed air from the power pin end. You should be able to feel the air pressure at the front end of the MIG gun. When the liner inevitably does reach the end of its life, you will likely encounter feeding issues. If a MIG gun cable is bent too sharply, the liner may become kinked. While the rest of the components inside the cable will return to shape, a coiled steel liner that has become kinked must be replaced immediately. If you take care to keep contaminants out of your liner and not abuse your MIG gun, you can expect an average of 6-12 months of service life.

How to Change a MIG Gun Liner

Proper installation is critical to the liner function. Liners may be damaged during installation and trimming a liner too short is a sure way to encounter feeding issues. Any burrs left from a poorly cut liner will catch your wire and may shave off metal or even cut through the wire entirely. To properly change a MIG gun liner, you will need the following: A new replacement liner of the appropriate diameter and length, a clean area long enough to lay your MIG gun out with the cable straight, a tool for clipping the liner, pliers, and a liner gauge or ruler. Some designs may also require a 5/64” hex key or a 10mm wrench. Here are a few key steps you need to take to change a MIG Gun Liner.
  1. Shut off the shielding gas and purge any remaining gas from your system. Turn off your machine and unplug it.
  2. Remove the MIG gun from the feeder and lay it out straight on a table or the floor. Remove the nozzle, contact tip, and diffuser.
  3. If the power pin has a guide cap or threaded nut, loosen it by turning it counter-clockwise. If the liner is retained with a set screw, loosen it with a hex key.
  4. Grip the liner from the rear with a pair of pliers and remove it from the MIG gun.
  5. Feed the new liner into the MIG gun from the rear, being careful to avoid kinking. Twist the liner clockwise if needed.
  6. If your power pin is threaded, tighten the liner collet with the 10mm wrench. If your power pin uses a guide cap, install it at this time. If your power pin uses a set screw, tighten while making sure that the o-ring is fully seated in the bore of the power pin.
  7. Trim the front end of the liner to the proper length according to the manufacturer’s guidelines. This distance may vary from 3/8” to ¾” depending on the design. Do not use helpers! A cutoff wheel or diagonal cutting pliers are the best choices. If there are any burrs, dress the end of the liner with a small round file.
  8. Reinstall the diffuser, contact tip, and nozzle. Reinstall the MIG gun on the feeder, making sure that the power pin is fully seated.
  9. Feed the wire into the MIG gun and set your drive roll tension.

MIG Gun Liners

If you take care of your liner, it’ll take care of you!

If you want to learn more about welding equipment & maintenance, we have plenty of material just for you!

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Troubleshooting your MIG welder cable

MIG Cable Problems – Symptoms, Causes and Fixes

Trouble Brewing

Here are a few symptoms you might notice when using your welding equipment.
Erratic or sputtering arc
• Gradual need to increase voltage at the power source
• Discoloration of the liner
• Contact tip burn back
• Inconsistent weld appearance
All indicate poor MIG welding cable conductivity and excessive resistance that can lead to heat build-up.

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It’s just a cable, what’s the big deal?

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cross section of MIG Unicable which carries, power, shielding gas and welding wire.On good days, the cable does exactly what it was meant to do: deliver power, shielding gas and smoothly-fed welding wire to your gun. But on a typical day, a cable suffers as much wear and tear as any other part of a MIG system for one reason: It moves as you move. And that repetitive motion can take a real toll on your cable causing fraying, tearing and breaking that can be devastating to your productivity.

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Why MIG Welding is Better Than TIG Welding

Arc welding processes are as varied as the workpieces they create, and choosing the right one is vital to your project’s success. While MIG and TIG welding both form the weld using an electric arc, the techniques are quite different, and choosing the wrong one can lead to more than one headache. Read on for the reasons you may want to choose MIG welding vs. TIG welding. (Click here to learn why TIG is better than MIG.)

 

MIG and TIG welding both use an electric arc to create the weld. The difference between the two is the way the arc is used. MIG (metal inert gas) welding uses a feed wire that constantly moves through the gun to create the spark, then melts to form the weld. TIG (tungsten inert gas) welding uses long rods to fuse two metals directly together.

RELATED: Most Common Welding Equipment and Processes

Diversity

A number of reasons make MIG welding the superior choice for your job. First, it’s more diverse. While TIG welding can be used on more types of metals, it’s limited in its effectiveness on thicker jobs. MIG welding can be used on aluminum, stainless steel and steel, and on every thickness from 26-gauge sheet metal to heavy-duty structural plates.

MIG welding holds this big advantage over TIG because the wire feed acts not only as an electrode, but also as filler. As a result, thicker pieces can be fused together without having to heat them all the way through. And because it uses filler rather than fusing, MIG welding can be used to weld two different materials together.

Speed

Another reason for choosing MIG vs. TIG is speed. A MIG gun is designed to run continuously for long periods of time, making them more efficient and productive than its counterpart. For large, industrial operations that require high production rates, MIG is the go-to choice. (It also lends itself well to automation). Oppositely, TIG welding is much slower process that’s focused on detail.

Cost

As with any manufacturing job, time equals money. And because the MIG welding process is so much faster, it’s also more cost-effective. MIG parts are also more readily available and far less expensive than TIG.

Ease

Finally, MIG welding is easier to learn and can be perfected after just a few weeks of training. In fact, it’s even been referred to as the “hot glue gun” of welding — just pull the trigger to start or stop the weld. MIG welders can hold and operate the gun with only one hand, making it a better option for beginning welders. TIG welding, on the other hand, is a specialized technique that requires the use of both hands and one foot — all doing separate things.

RELATED: How to start a career in welding

For help with your MIG setup, download our free MIG Ultimate Troubleshooting Guide.

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