Waste Not, Want Not

Planned downtime for preventive maintenance in the welding operation is not time wasted. Rather, it is a crucial part of keeping production flowing smoothly and avoiding unplanned downtime. Proper maintenance can extend the life of consumables and equipment, and help prevent issues such as birdnesting or burnback that can lead to costly and time-consuming troubleshooting and rework. Keep in mind a few simple maintenance tips and best practices to get the most from your MIG gun and consumables.

PROPER INSPECTION
Prior to welding, ensure all connections are tight and that consumables and equipment are in good condition and free from damage. Start with the front of the gun and work your way back to the feeder. A tight neck connection is essential to carry the electrical current from the welding cable to the front-end consumables. Loose connections at either end of the neck can cause poor electrical conductivity, leading to weld defects and, potentially, overheating of the gun. When using a rotatable neck — one that allows the gun neck to be rotated to the desired position for welding, for increased flexibility and operator comfort — make sure the hand nut on the neck is tight and that the neck is secure in the cable fitting.

Also, be sure to visually inspect the handle and trigger to check there are no missing screws or damage. The cable should be free of cuts, kinks and damage along the outer cover. Cuts in the cable can expose the internal copper wiring and create a potential safety hazard to the welding operator. In addition, these issues can lead to electrical resistance that causes heat buildup — and ultimately cable failure. In checking the feeder connection, make sure the power pin is fully inserted and tightly connected, otherwise it can cause birdnesting of the wire at the feeder. A loose connection can also cause electrical resistance at the joint, which could lead to an overheated gun.

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LINER
A clean liner that is the correct size is important in producing quality welds. 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. A liner that is cut too short can cause wire feeding problems. Follow the manufacturer’s instructions for proper trimming and installation of the wire for the best results. Also, take care to keep the liner off the floor during installation to avoid picking up dirt and debris that could enter the weld pool and cause defects. A dirty liner reduces shielding gas flow, which can lead to porosity in the weld. Fragments of welding wire can also chip off and accumulate in the liner. Over time, this buildup can cause poor wire feeding, birdnesting and burnback.

To maintain your liner, periodically blow clean compressed air through it to clear out dirt and debris. This task can be done in a few extra minutes during wire changeovers or when removing the wire from the gun — and helps save considerable time in troubleshooting problems later.

CONSUMABLES
MIG gun front-end consumables are exposed to heat and spatter and therefore often require frequent replacement. However, performing some simple maintenance can help extend consumable life and improve gun performance and weld quality. The gas diffuser provides gas flow to the weld pool and also connects to the neck and carries the electrical current to the contact tip. Make sure all connections are tight, and check the diffuser’s O-rings for cracks, cuts or damage. The nozzle’s main role is to focus the shielding gas around the weld pool. Watch for spatter buildup in the nozzle, which can obstruct gas flow and lead to problems due to inadequate shielding coverage. Use welper pliers to clean spatter from the nozzle.

The contact tip is the last point of contact between the welding equipment and the welding wire. Keyholing of the contact tip is a concern to watch for with this consumable. This occurs when the wire passing through the tip wears an oblong-shaped slot into the diameter of the tip. Keyholing can put the wire out of center and cause problems such as an erratic arc. If you are experiencing wire feeding issues, try changing the contact tip or switching to a larger-size contact tip. Tips that look worn should be replaced.

FINAL THOUGHTS
Taking the time for preventive maintenance can pay off in less downtime in the long run. Along with that, always remember to properly store your MIG gun consumables to help you achieve the best results and extend the life of your equipment. When not in use, the gun should be stored in a coiled position, either hanging or lying flat, such as on a shelf. Do not leave MIG guns on the floor of the shop, where there is a chance the cable could be run over, kinked or damaged. Ultimately, the better care you take care of this piece of equipment, the better results you can achieve in the weld cell.