CANADA'S LEADING INFORMATION SOURCE FOR THE METALWORKING INDUSTRY

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CANADA'S LEADING INFORMATION SOURCE FOR THE METALWORKING INDUSTRY

CANADA'S LEADING INFORMATION SOURCE FOR THE METALWORKING INDUSTRY

Troubleshooting MIG guns

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By Andy Monk

Overcoming common problems and consumables issues

 

Making a high quality MIG weld depends in part on having a gun and consumables that are functioning properly. When something isn’t right with these components, problems can occur. Here are some tips for solving common consumables and gun-related problems associated with MIG welding.

Contact tip burn back can simply occur from time to time, but it can also be caused by improper equipment set-up. Check for improper contact tip recess or improper wire stick out. Adjusting the distance between the gun and work piece can resolve the problem, as can replacing cables to prevent a faulty work lead/ground that may lead to burn back.

Erratic wire feeding can be caused, in part, by a worn or kinked liner, dirt in the liner or the wrong size of liner. Trimming the MIG gun liner according to the manufacturer’s recommendations is key, as is using the proper tools to cut it. Some manufacturers offer a liner gauge to determine proper length and/or a spring-loaded module that combines with a front-load liner to minimize issues of an incorrect liner length. The modules, housed in the power pin, put forward pressure on the liner and allow up to 1-in. forgiveness if the liner is too short.

Short contact tip life can stem from the wrong size contact tip, exposure to excessive heat or erosion caused by the wire. If the contact tip is melting, it’s likely a result of exceeding the rated amperage or duty cycle. If the wire is prematurely wearing out the contact tip, the drive rolls may be creating small burrs on the wire that can erode the inside of the tip. Setting the drive roll tension too high also can create deformities in the wire. Rectifying these issues can help lengthen the contact tip life.

A gun running hot is likely caused by exceeding the rated amperage or duty cycle, or loose power connections or a degraded power cable, which can cause excessive resistance in the weld power circuit. Make sure to keep parameters within the gun’s range or use a higher-rated gun. Clean and tighten connections and replace those that are worn out. A discoloured liner is a sign of loose power connections or a degraded power cable. Also, check to make sure the work lead connection is tight and free of obstruction. SMT

Andy Monk is product manager for Bernard, Beecher, IL.

 

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