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Selecting the right MIG gun for your welding application, and maintaining it properly, is just as important to your overall productivity as any other part of the welding operation.

Unfortunately, MIG guns are very often an overlooked part of the welding system. The reality is, however, that in addition to being responsible for delivering the current, wire and shielding gas to the weld puddle, your MIG gun can also have a significant impact on your weld quality and your bottom line.

Similar to selecting your power source or wire feeder, the goal is to find the most cost-effective MIG gun that is capable of providing you with the performance that you need for your welding application. Regularly executing preventive maintenance can then help you protect that investment.

Here are some tips to help you select the right MIG gun for your application and maintain it properly.

Choose the Right MIG Gun for Your Application

We all have the tendency to fall victim to the "bigger is better” philosophy. When it comes to purchasing a MIG gun, however, that thinking may cost you more money than is necessary for this equipment. It can also lead to costly downtime.

It is a common misconception that a welding procedure requiring 400 amps, for example, also requires a 400-amp MIG gun capable of operating at those amperage levels 100 percent of the time (i.e., 100 percent duty cycle). The fact is you spend time moving parts, grinding, tacking and completing other such tasks as opposed to welding nonstop. That means that you can often purchase a smaller amperage MIG gun - a 300-amp model would suffice - for applications in which duty cycle is less than 100 percent (e.g., 60 percent) for less money and still have it operate at the appropriate capacity.

A smaller, lower-amperage MIG gun also weighs less and can help reduce wrist fatigue that could lead to downtime. It offers the added benefit of being easier to maneuver, which can help improve weld quality, too, and lessen rework.

When possible, using shorter power cables on your MIG gun can further minimize costs and downtime. As a general rule, shorter power cables are less expensive and, like a smaller MIG gun, offer better maneuverability. Shorter power cables also help minimize wire-feeding problems associated with kinking and coiling, so you can spend more time welding and less time resolving these issues.

Other factors you should consider when selecting your MIG gun:

  1. Select guns with a rigid strain relief (the connection between the power cable and power pin). A good strain relief helps minimize kinking that can lead to poor wire feeding, an unstable arc and poor weld quality.
  2. Select a trigger that is comfortable and easy to service. MIG guns are available with a variety of trigger options (e.g., standard, locking, dual schedule, etc.) and you may find that you prefer one over the others. Also, look for sturdy triggers that will withstand work site abuse and that can be easily replaced should one of the mechanics fail. Doing so can minimize downtime for maintenance and repairs.
  3. Find the right neck for your application. Typically, MIG gun manufacturers offer fixed, rotating and flexible necks in various lengths and angles. Having the right one for your application makes it easier to reach the joints that you need to weld and can help you get your repairs done more quickly and easily. Look for a neck with good armor to protect it against damage that could lead to electrical shorts or premature failure.
  4. Consider using the smallest handle that can still meet your amperage needs. As with a smaller gun, smaller handles are easier to maneuver and can lessen fatigue. Some manufacturers also offer ventilated handles that help reduce heat and make it more comfortable to use for longer periods of time.

Maintaining Your MIG Gun

Regularly inspecting your MIG gun can be an important part of reducing costs and gaining good welding performance. Fortunately, preventive maintenance (PM) for a MIG gun doesn't have to be time consuming or difficult. Consider these key factors.

Check the feeder connection: Regularly check the wire feeder connection (where the power pin plugs into the feeder) to be certain it is tightened properly and that there is no dirt or debris on it. Loose or dirty wire feeder connections can cause heat to build up, leading to voltage drops that adversely affect the welding arc and may cause premature gun failure. Tighten the connection according to the manufacturer's specifications or replace the direct plug if necessary to obtain a secure fit. Also inspect the O-rings for cracks that could lead to gas leaks, and replace them as necessary. Gas leaks often cause spatter and porosity, which increases downtime for cleanup and rework.

Properly care for your MIG gun liner: It is not uncommon during the course of welding for the MIG gun liner to become clogged with debris, particularly from the welding wire. Over time, however, this accumulation of debris can lead to poor wire feeding, bird-nesting and burnbacks that require downtime to rectify. To maintain your liner, you can use compressed air to clear out potential blockages when you change wires. Also, tracking the length of time it takes for your liner to wear can help you better know when to replace the next one before you encounter problems. Always follow the manufacturer's recommendation for trimming and installing the liner to prevent kinking and wire-feeding problems.

Inspect the handle and trigger: Typically these components require little maintenance beyond visual inspection. Regularly look for cracks on the handle or missing screws. Check that your MIG gun trigger is not sticking or otherwise malfunctioning. Replace these components as necessary.

Check the MIG gun neck: Loose connections at either end of the neck can cause electrical resistance that leads to poor weld quality and/or consumable failures. Check regularly to ensure tight neck connections. Also, visually inspect the insulators on your MIG gun neck and replace if damaged. These insulators prevent electrically live components from exposure, ensuring your safety and the longevity of your equipment.

Visually inspect the power cable: Power cable maintenance is a very important part of eliminating uncessary equipment costs. Regularly inspect the power cable for damage, including cuts or kinks, and replace it as necessary. Cuts in the cable can expose copper wire and lead to a potential shock hazard, while kinking obstructs gas flow and wire feeding. The latter can lead to weld defects and arc instability that require downtime to remedy.

Be mindful of your consumables: Frequently inspect your MIG gun nozzle and contact tip for signs of spatter build-up, which can obstruct shielding gas flow and cause weld defects that will need to be reworked. Spatter build-up can also cause your consumables to fail prematurely. Replace both consumables if spatter build-up appears or clean according to the manufacturer's recommendation. Also, be certain that these components (and the gas diffuser) are securely connected. Loose connections can increase electrical resistance, which in turn leads to poor welding performance and can shorten the life of your consumables, adding to your overall costs.

Remember, just like the power source and wire feeder, your MIG gun can impact your weld quality, productivity and costs. Taking the time to select the proper MIG gun and maintain it regularly, however, can help this equipment last longer and ensure that you spend more time welding instead of resolving problems.

Top image: The nozzle and contact tip (as shown in this cut-away) are designed to fit securely together. Check the connections regularly to ensure they are snug, as this will help prevent electrical resistance that can lead to premature failure.

Grant Peppers is an industrial solutions manager for ITW Welding North America, which is composed of Bernard, Hobart Brothers, Miller Electric Mfg. Co., Tregaskiss and Weldcraft.




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