How to Change Liner in MIG Welder

A good MIG liner is a gem. Liners can break or make the MIG welder performance bad which is why it’s advisable to regularly clean your liner for better performance. Occasional cleaning gets rid of the drag or buildup. Remember, the liner is a consumable meaning that eventually you will have to replace it completely. Liners wear out with time, which explains the reason why they get replaced. 

Liners need good maintenance to maintain their rigidity and flexibility. Bending the cable causes problems and tight bends between these wires increase tension and friction between the edges which can bring your liner out of the MIG gun.

Accumulation of metal fragments in the liner results in unintentional wear and tear. If the situation persists for long, you start having large deposits of debris in your wire feed leading to blockage and causes a drop in performance rate. 

The guide below helps you understand how to do just that and get back to doing quality welds without problems. Before you do anything, remember to put the power supply off to avoid electrical shocks and disconnect your MIG gun from the wire feeder. 

how to change liner in mig welder

Understanding MIG Gun Liners

MIG gun liners are helically wound wire or tube.

MIG gun liners are an important component of the MIG gun. Mainly, the liner is responsible for guiding the welding wire via the wire feeder and through the MIG gun cable to the contact tip.

Any problem with the liner interferes with the smooth functioning of the gun. In short, if the wire is not properly fed results in low quality welds increasing your operating costs and downtime. 

Doing proactive maintenance helps eliminate MIG welder liner problems before they occur and ensures you never experience operator downtime. Maintenance prevents equipment failures, so buy quality liners that maintain consistent internal diameter. Any variation in the internal diameter causes wire feeding problems and will cost you serious downtime to replace.  

General wire feeding problems are responsible for poor weld quality and affect gun performance. These problems include erratic wire feeding, bird nesting, and wire-burn back. They are caused by incorrect drive rolls, improper wire liner installation, and clogged liners among others. 

How to Replace MIG Gun Liner

The first step is to get the right tools for the work. Get a wrench because it is useful in loosening various components and tightening them back after changing your MIG welder liner. You also need pliers. 

  • Remove your old liner together with the welding wire, contact tip, gas diffusor, and nozzle. Unscrew then remove the liner from your MIG gun. Lay the MIG gun down straight to help you unscrew the liner easily. 
  • Feed the new liner and screw the liner back into the MIG gun. Trim it to about 3/4 inch after it appears through the neck of your welding gun. Only the 3/4 inch should stick out. Cut the liner carefully and ensure you don’t leave any kinks because they can catch the inside of the MIG gun. 
  • Reattach your liner to the welder then put back the contact tip, welding wire, gas diffusor, and nozzle on your welding gun. Tighten them all in place using the wrench until all are secure and nice. 

The steps are simple and easy to manage. Your main concern should be finding the quality liner. Anyone can change a liner in MIG welder by following the above simple steps. 

However, it’s vital to know the reasons why you are changing your liner. Proper MIG gun liner replacement optimizes performance. Plus, it reduces operator downtime, wasted wire, and costly rework. 

MIG Gun Liner Sizes

MIG gun consumables like MIG welder liner play a significant role in weld quality and gun performance. The liner extends from the gun to the power pin and is the passage for the welding wire feeds. 

A proper liner installation is vital to quality welds and optimal gun performance. Improper line installation results in problems like bird nesting, more debris on your liner, and wire feeding problems. 

Pick the right liner size that maximizes your MIG gun performance. Small diameter welding wires ranging from 0.023 inches to 0.045 inches have low columnar strength.  Pairing them with oversized liners makes the wire drift or wander inside the liner. This causes poor wire feeding and leads to premature liner failure because of excessive wear. 

Larger diameter welding wires ranging from 1/16 inch to 1/8 inches have higher columnar strength. Ensure the liner size you pick is large enough to handle the welding wire and feed properly. 

If you intend to use oversized liners, then pay attention to its outer diameter in relation to your MIG gun’s inner tube diameter. An overly large outer liner diameter impedes gas flow in the torch resulting in poor welds. Use flat wound welder liners to fit the limited space in your MIG gun. This allows you to perfectly accommodate those large gauge welding wires. 

The best wire liner depends on your MIG gun liner size, and the filler metal you use to weld. The best way to ensure you enjoy optimal performance includes; 

  • Pairing the line size to the right welding wire size 
  • Examine the MIG welder liner material to ensure it’s high quality 
  • Blowing out the MIG welder liner when making spool changes to eliminate debris and ensure you have a smooth feed. 

Symptoms of Bad MIG Liner

How do you know you have a liner problem? You have liner issues when you see the symptoms mentioned below. Expect one of the causes to be MIG welder liner. Problems like this during welding are often frustrating but don’t be stressed up about it because you can change the liner in the MIG welder easily by yourself. 

Poor Wire Feeding

Erratic wire feeding happens when your MIG liner is worn out or incorrectly trimmed when replacing, leading to excessive buildup of debris. The best solution is to replace the liner and correctly trim the liner during installation. Alternatively, you can use consumables systems that lock your liner in place at the back and front when aligning it concentrically to the power pin and contact tip. 

Your Plugs are Dirty

When the plugs get too dirty, it means your liners are worn out. Remember, liners are consumables. Even as you clean the liners regularly, eventually they still wear out and will need to be changed. Liners pick up much metal dust causing a buildup affecting performance. When this happens, change the liner in the MIG welder. 

Frequent Contact Tip Burn-backs

This is a problem consistent with a bad MIG liner and happens when the wire feeder is behaving erratically. 

Birdnesting

This happens when the path of the welding wire via the MIG gun is blocked. The wire feeder push causes a mess of wire commonly referred to as bird nesting. Also, it can be caused when you trim the liner too short, the liner is clogged or you use the wrong liner size. 

Electrical Short

Liners are unable to carry welding current, so a dramatic loss of current at the welding arc makes it lose cable connections. This can degrade the cable making the path have less electrical resistance. You will see a discolored liner or excessive heat buildup on the power cable. This discoloration is mainly because of the heat passing through the liner instead of the MIG gun power cable. The best remedy is to replace the liner. 

Experience Kinks

Whenever your liners develop kinks, it’s never a good sign. You need to replace the liner immediately, once kinks are there, no cleaning can repair it meaning they are unfixable. Kinks cause bird nesting in the liner or lines which affects the smooth positioning of the liner at the tip of your MIG gun. 

As a consequence, you get low-quality welds, downtime problems, or overheating problems, all of which affect your welding work. Changing the MIG welder liner is a smart move to preserve optimal performance and get quality welds. 

Types of MIG Welder Liners

There are different MIG welder liner types used in both robotic and semi-automatic applications. Picking the right type depends on your welding operator or maintenance technicians. There are three liner types namely

Conventional liners 

Front-loading liners 

Front-loading lines with a spring-loaded module 

Conventional Liners

The most common liners and are installed via the back of the MIG gun. They are commonly used in MIG welding units for industrial uses. The changeover in these liners is tedious and lengthy. Every twist causes the cable to shrink and grow. The liners are often 25 feet long. Most welding machine operators are conversant with the liner and the installation process. 

Front-loading Liners

The liner installation happens from the front of the MIG gun. The liner saves time and the welder doesn’t need to leave the front of the welding Gun for a changeover. In short, you experience no downtime. 

However, like the convention liners, the free-loading liner doesn’t grow or shrink with every cable twist or movement. Standard front-loading liners come in full length while jump liners are shorter and a foot long. Jump liners only replace the worn-out section which in most cases is the neck of the MIG gun. 

Free-loading Liner with Spring-loaded Module

To install the liner insert the spring-loaded module into the power pin and give a maximum of one-inch allowance of motion as your cable twists and springs down and up. The liner works efficiently even when the liner is not trimmed correctly. Using the neck liner when it’s appropriate or beneficial.

Teflon liner for MIG welder

This is a fluorocarbon solid liner that is super slippy and feeds soft wires perfectly through your MIG torch. MIG braze and aluminum need a Teflon liner in the MIG torch to allow smooth wire feeding when welding. Aluminum has a rough surface making it easy for your drive rollers to grip because of the low tensile strength and easiness to spool. 

Drive rollers only grip a small area of the welding wire as it pushes it through the MIG torch. Pushing the welding wire through smaller areas is very difficult which is the reason welders use 4-roll wire feed units as opposed to 2-roll wire feed units. The latter grips and pushes your wire over a larger area reducing any likelihood of birdnesting. 

Teflon is popular and highly useful because it makes it easier for you to push the wires through the MIG torch. Teflon comes in different bore sizes all depending on the wire size you intend to use. Always ensure the Teflon MIG liner is fitted properly for better welding current transfer. 

Teflon is also known as PTFE or Polytetrafluoroethylene and has a higher melting point than polyethylene. Teflon is ideally used in high-temperature welding applications. 

Mostly, Teflon is used for applications with brass neck liners and a water-cooled MIG torch. PTFE is abrasion resistant making it suitable for a variety of wires. 

Final Thoughts

Knowing how to change a liner in a MIG welder is crucial and ensures you enjoy optimal performance and weld quality. Be on the lookout for the symptoms of bad MIG liner and take decisive action to prevent downtime and poor weld quality. 

Understand the operation of the MIG liner and the various types of liners you are using in your welding machine. Each type of liner has both advantages and disadvantages. 

Pick a type with the best compatibility. Welders have different preferences on liner type and check the manufacturer guidelines on trimming the MIG gun liner. 

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