Neck

The neck carries the electrical current from the welding cable to the consumables.

Loose connections at either end of it can cause poor electrical conductivity, which can lead to weld defects and further equipment failures due to the heat generated by electrical resistance. Check to ensure tight neck connections on a daily basis.

MIG gun necks also feature external insulators that protect the electrically live components from being exposed. Exposed electrical components near the handle can create a safety risk, and exposed components near the consumables could arc to the work piece and damage both the gun and the work piece. The insulators should be checked, at least, weekly and replaced as needed.

Consumables

Because of their exposure to heat, spatter and general abuse, consumables require frequent replacement. That doesn't mean, however, that you can't save time and money through simple maintenance.

In addition to providing gas flow to the weld pool, the gas diffuser connects to the neck and carries the electrical current to the contact tip. Loose connections between the diffuser and the neck or the diffuser and the contact tip can cause gas leaks or weld quality and equipment problems related to poor conductivity and built up electrical resistance.

These should be checked during nozzle changes and tightened to the manufacturer's specifications using the recommended tools.

Most diffusers also use O-rings to seal in the shielding gas, and like their counterparts at the back end of the gun, you should check these for cracks, cuts or other damage and replace them as necessary whenever you remove the nozzle.

The nozzle's main role is to focus the shielding gas around the weld pool. Spatter can build up inside the nozzle and obstruct the gas flow, resulting in porosity, excessive spatter and other problems related to inadequate shielding gas coverage.

The nozzle and nozzle insulator can also become damaged from cleaning out the built-up spatter.

Depending on the amount of spatter created while welding, you should check and clean the nozzle several times per day. A pair of welding pliers is the most common tool for cleaning nozzles, but there are other specialized tools designed specifically for reaming out spatter from the nozzles.

The nozzle insulator keeps the copper or brass nozzle body separate from the electrically live consumable components, so a damaged insulator could cause the nozzle to arc to the workpiece.

A visual inspection of the nozzle insulator is usually sufficient to determine proper condition, and damaged insulators require replacing the entire nozzle.

The contact tip is the final piece of the consumables set, and the last point of contact between the welding equipment and the welding wire. As the wire passes through the contact tip, it can erode the inside of the tip bore, leading to interruptions in the electrical current and poor arc control. The tip can also become covered with spatter and cause inadequate gas coverage.

Welding operators often wait to change the contact tip until a weld problem develops, however, the time it takes to correct a weld problem can be considerably greater than the time it takes to visually inspect and replace the contact tip on a regular basis as a standard maintenance procedure.

Industrial grade welding equipment is built with productivity in mind, but even the best equipment eventually will breakdown. Whether you catch the equipment malfunction in its early stages or after serious problems develop is up to you, however. Through the implementation of the simple, proactive maintenance steps outlined above, you can greatly extend the service life of your equipment and avoid the costly correction of weld defects in the event of equipment breakdown.