Guide to Install and Replace Conventional the MIG Welding Liner

Getting to know about the installation and replacement of MIG welding liner components without the need for years of experience of spending a lot of money to learn it might be amusing to many welders. This not only helps you get your welding unit to run throughout the year without any breakdowns or repairs, but it might also help you get some good amount of cash for doing such repairs and installation for other welders.

Here is a guide giving you the pre-requisite knowledge about the installation process, tips to optimize your repairs, and help you grow in your welding career. In this era, it is necessary to minimize downtime and operate in the most efficient way possible.

Description

MIG Welder Liner
Source: Daddys Pick
There are several reasons that cause downtime in the welding industry like grounding problems, gas leaks, contaminated material malfunction in the machine, and sometimes even broken-down internal components. Wire feed problems and MIG gun liner issues make the situation even worse.

Generally, when we talk about wire feed problems, there is a lot of issues that are comprised of like erratic wire feed, wire burning, and even bird-nesting. Incorrect drive rolls, incorrect tip size, improper installation of wire liner, and clogged liners are some of the causes of wire feed problems.

The MIG gun liner is one of the simplest components used in the MIG welding setup but has the most prominent effects on the fabrication downtime which we had mentioned at the very beginning.

Types

Conventional Liners

Conventional MIG Welder Liner
Source: https://www.bernardwelds.com
These gun liners are installed through the back of the gun. They are used in MIG welding units which have only industrial uses. The changeover is a lengthy and tedious process. The cable keeps growing and shrinking with more and more twisting.

Front-loading liners:

Front-loading MIG Welder liners
Source: https://www.tregaskiss.com
These MIG gun liners are installed in the front of the gun. It reduces downtime and helps provide more time-saving advantages. Here the wire does not grow or shrink as the cable begins twisting.

Front-loading liners with a spring-loaded module:

Allows more than 1 inch of the motion of the cable twists and more. If you can trim the liner properly, it can be more forgiving than being incorrect.

MIG Gun Liner Properties

A MIG gun liner is a device that has a tube or a helical wire that is wound and helps in passing the welding wire to the gun and on to the contact tip. You must be sure about the MIG gun liner you purchase as the type and size of the liner is essential to be a match with the type and diameter size of the wire feed used.

Diameter Size

Even if some do not like it, there are many welders who prefer using liners of larger diameters in a hope that the wire feed does not get damaged because of the accumulation of a large about of debris.

On the other hand, liners with smaller diameter have lower column strength and stay inside the MIG gun liner. It leads to premature wear and tears due to the continuous rubbing of their surfaces and other serious feeding problems too. This causes ‘birdnesting’, which is the tangling of the welding wire between the drive roll and end of the torch and wastes some wire feed.

Drive roll Birdnesting
Source: https://weldingproductivity.com
Hence, large-diameter wire feed has a larger column feed strength and it should be accompanied by a limited liner’s outer diameter that must be used. If you use a compressed airliner, it can help you blow out the debris from the liner and increase its lifetime.

Installation Process:

Conventional MIG Welding Liner:

Step 1
  • MIG welding is a versatile welding process and hence the workpiece must be as clean as possible before working.
  • Do make sure the power supply is ‘OFF’ and the MIG gun is completely removed from the feeder before processing.
  • Make sure you remove the nozzle and gas diffuser before doing any process.
  • If your MIG gun has a liner-set screw, then loosen all the set screw using a 5/64-inch Allen wrench.
  • Whereas if the MIG gun is a thread-in liner type screw, then use a 10mm wrench, turn the thread-in liner collet counter-clockwise until the liner is free from the power pin.
  • Straighten the gun and try to remove the conduit liners with the help of some cutting pliers.
Step 2
  • Feed the new/ replacement liner through the gun using slow and small strokes to avoid any distortions. Twist the liner clockwise.
  • If the power pin uses a liner set screw:
  • Seat the liner retainer with an o-type ring inside the bore of the power pin properly.
  • Now tighten the liner set screw to keep it stored properly.
  • If the power pin used by you is of thread-type:
  • Use a 10-mm wrench to turn the liner collet in a clockwise direction.
  • Make sure you tighten it.
Step 3
  • Push the liner back into the MIG gun and let it stay there for some time.
  • Using the Liner Gauge, you can trim the conduit liner with ½ inches or 3/4 inches stick out.
  • Now you can replace the nozzle, contact tip, and the gas diffuser on the neck of the gun as they are highly imperative.

Jump Liners:

  • Remove the nozzle and the gas diffuser. Remove used Jump Liner from the rear end of the neck. Remove the neck of the gun also.
  • Once done, place a new ‘Jump Liner’ and the liner stop must be properly sealed at the rear end of the neck.
  • Now take the tapered end of the neck and insert it into the end fitting of the gun handle. Install the neck.
  • Trim Jump Liner to the dimensions shown here.
  • Trim the liner at the nozzle of the neck as the following guidelines:
    • S-1 and D-1 Centerfire™ Gas Diffusers
    • 4335 and 4435 gas diffusers
    • D118Q Gas Diffusers
    • D114Q Gas Diffusers
  • Finally, install the gas diffuser, contact tips, and nozzle.

Optimize Liner Performance:

The quality and maintenance of the MIG gun liner make a huge impact on weld quality. The proper installation and regular maintenance of these gun liners can help reduce downtime and unwanted expensive work.Follow these guidelines, to maintain a good-quality liner performance:

  • It is recommended to wear a new pair of gloves to keep the MIG gun liner clean and debris-free.
  • Please do not drag the liner on the floor during the changeover.
  • Make sure the liners have their seats securely kept in the retainer in the power pin.
  • Remove any excess burr present on the liner surface using wire cutters once you have installed the gun liner. This prevents the liner to catch fire, burn-back, or any kind of an unstable arc in its front.

Tips to Install Conventional Liners:

  • Make sure you take the wire and liner out from the back of the welding gun by cutting the wire and removing the power pin.
  • Always push and feed the liner via the back of the MIG gun and also make sure it passes through the power pin.
  • When you refit the gun liner from conventional to a front-loading liner, the liner must be fitted to the back of the MIG gun and this is because it needs a receiver on the back-end of the gun for the proper accommodation of the liner.

Tips to Install Front-loading Liners:

  • Make sure the gun is straight and the cable has a flattened feed before you remove the front-end consumables. This provides more penetration for the liner feed to pass through the power pin.
  • Removing the beads of the molten wire can help in proper welding profiles after the welding process by trimming out the wire at the front of the welding gun.
  • You can avoid kinks in the liner by using short strokes to feed the liner at the front.
  • Once you find out that the front-loading liner clicks in place in the MIG gun end and once you hit the receiver in the power-pin, make sure you place the liner gauge at the top of the liner and trim it as required later on.
  • Remove the coiled liner and put it on the brass end. This goes to the receiver at the back-end of the MIG gun through its neck.