Ensure Proper Install of Consumables

When installing consumables, ensure proper tightness. This does not mean only hand-tightening. Most often in the field poor consumables life is caused by loose tips. A loose connection causes electrical resistance, resulting in heat. This will cause melting of the diffuser and tip, and cause issues with the welding torch. Over time, torch tips will loosen due to heat cycling and the vibration of welding. Check tip tightness periodically to ensure that the tip stays tight, creating less chance of issues.

Check for tightness on cable connections to the welding-gun neck. And, don’t pull on the gun as a means to move feeders around, whether boom- or cart-mounted. The gun and cable are not designed to be a leash. Doing so may pull the copper out of its connection point and ruin the welding torch, leading either to a torch repair or replacement. 

Mind the Liner

GMAW gun liners guide welding wire through the gun to the contact tip. The liner serves as the backbone of a GMAW gun. This makes liner installation and care critically important. Any problems in the wire-feeding process almost certainly relate to the liner. The liner essentially supports welding wire across 15, 20 or 25 ft. With the liner tasked with so much work, there’s plenty to keep an eye on. First, let’s discuss the cut. Welders on occasion use welding pliers to cut the liner. This is not ideal, as these pliers usually lack hardened blades and proper cutting geometry of the blades. The blades, not very robust, typically won’t last when used to cut through the thick, hardened wire in a liner. Use hardened blades with more obtuse cutting edges. They’ll stay sharp longer and provide nice, clean cuts. Such burr-free cuts deliver clean liners. Using a poor cutting tool will bend the coil and potentially block the wire-feeding path. As the wire passes through the liner, it then will rub on the bent edge and the welder will feel the chatter. Burnbacks and bird-nesting result—aggravating and time-consuming problems to address. 

We recommend laying the gun perfectly straight, with no liner helix twists or coils. Why? The liner and cable move independently when bending and manipulating the cable, and the liner may float. Better to cut the liner with the liner and cable in alignment, and relaxed in their natural positions.

When to Change Consumables

When is it time to change consumables? Prematurely changing consumables wastes time and money, whereas too late affects weld quality and productivity. One common issue related to consumable life is burnback—when the wire melts in the contact tip. Grinding the end of the tip off is not a quick fix. Instead, replace the tip. Grinding, particularly in industrial applications, likely will consume more time compared to replacement. Operating a grinder requires careful attention to safety protocols and the use of appropriate personal protective gear, and altering the distance between the tool tip and the workpiece can impact weld parameters. 

When reaching the end of a tip lifecycle, keyholing or vaporization of the melt will occur. That’s a primary failure point. Wandering arc and other problems also indicate the need for tip replacement. Eventual tip failure is just the nature of the beast in welding. Premature tip failure, however, demands a closer look. Such failure may be caused by bad cast (diameter of the welding wire as it unspools), improper setup  parameters on the welding machine or improper wire-drive-reel tension. Addressing these problems will add life to the welding tip. MF

Jason Bonnell is a product manager for Miller Electric Mfg.’s Industrial Equipment division, and Roger Robey is a technical support specialist with Bernard and Tregaskiss, all ITW Welding companies. For additional information, watch Miller Electric Mfg.’s “Optimize Your MIG Gun Consumables” video.

See also: Bernard Welding, Tregaskiss, Miller Electric Mfg. Co.

Technologies: Welding and Joining

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