Time spent maintaining a MIG gun can be considered downtime, but that doesn't mean it is time wasted.

Proper gun maintenance can substantially extend the service life of the equipment and reduce the even greater cost of weld rework. Diagnosing and correcting minor problems, such as loose connections, can avert more serious equipment failures and weld defects.

Below are recommended maintenance tips for most brands of MIG guns.

Always follow the gun manufacturers recommended safety precautions, including disconnecting the gun from the feeder and allowing it to cool before performing any maintenance that could expose live electrical circuits.

Feeder Connection

A loose or dirty wire feeder connection often causes electrical resistance and heat to build up at the point of the connection, leading to drops in voltage, an erratic arc and premature equipment failure.

You should manually check the connection on a weekly basis or whenever you install the gun to the feeder to ensure that it is clean and fits tightly to the wire feeder. If the connection is loose and cannot be tightened according to the manufacturer's specifications, it is best to replace the direct plug with one that fits securely.

Clean a dirty direct plug as needed with electrical contact cleaner.

Another area of the feeder connection that can fail are the O-rings that provide an airtight seal through which the shielding gas enters the cable hose.

These O-rings can become dry and crack over time, and they also can be cut or damaged when the gun is installed. Gas leaks caused by faulty O-rings can cause porosity, excessive spatter and create other defects that require rework and waste gas. They should be checked and coated with a silicone lubricant whenever the gun is removed from the feeder.

Cable

The cable is usually the only part of the MIG gun that requires full replacement when it becomes damaged.

For that reason, cable maintenance is very important to avoiding unnecessary equipment costs. Gun cables should be inspected visually daily for cuts, kinks and other damage. Cuts in the cable could expose the internal copper wiring and create a potential safety hazard.

The cable also should be routed from the feeder to the welding location as straight as possible. Severe bends in the cable can obstruct the gas flow and wire feeding, leading to porosity, an erratic arc and other weld deformities that take valuable time to remedy.

Liner

The liner is often both the most difficult part of the gun to inspect and maintain, and one of the most frequent sources of weld troubles. Fragments of the welding wire often chip off and accumulate as it travels through the liner. Over time, these accumulations can cause poor wire feeding, birdnesting and burnback. These problems can also occur if the liner becomes kinked or if the cable is bent at too much of an angle.

Removing the liner for full inspection and cleaning is time consuming and unnecessary if there aren't existing problems. Instead, to maintain an unclogged liner, use compressed air to clear any potential blockages during wire changeovers or whenever you remove the wire from the gun.

Spending an extra few minutes clearing out debris from the liner can save considerably more time than troubleshooting weld defects and equipment problems that can result from blockages.

Handle and trigger

The handle and trigger generally require little maintenance beyond visual inspection.

Check that there are no missing screws or damage to the handle and test the trigger to make sure it is not sticking or otherwise malfunctioning. These inspections take only seconds and should be done every time you use the gun.

A damaged handle runs the risk of causing electrical shock if there is any exposed copper from the weld cable. A dirty, damaged or simply worn out trigger can cause a number of weld problems and should be replaced with a new trigger.