Check out this guide for troubleshooting common GMAW gun and consumable problems. Here's how to keep your MIG equipment at its best.
Aug 1, 2009 12:00 PM, BY ANDY MONK Product Manager Bernard
MAKING a high-quality MIG weld is no easy task. But making a high-quality MIG weld when your gun and consumables aren't functioning properly is just about impossible.
Porosity, excessive spatter, undercut and burn back are just a few of the problems that can occur when something's not right with these components. Troubleshooting weld defects can be a difficult task, since any single problem can be caused by a variety of factors.
It is often easier to avoid weld defects from occurring by conducting a thorough check of your MIG gun and consumables prior to welding than it is to troubleshoot an existing issue. Problems will inevitably occur, however, and being able to quickly and accurately identify their source will save you both money and frustration.
The following is a guide to solving many of the most common consumables and gun-related problems associated with MIG welding.
Wire does not feed — There are a number of problems that could cause the wire to not feed, including issues related to the feeder relay, control lead, adapter connection, liner or the trigger switch.
Begin troubleshooting this problem by checking whether the drive rolls are turning when the gun trigger is pulled. If they are not turning, an electrical continuity failure is occurring. Check the terminals and connector contact pins to ensure the gun is properly connected to the wire feeder. The wire can also fail to feed if the trigger switch is broken, or control leads in the gun cable are damaged. If this is the case, they will need to be replaced.
If the drive rolls are turning but the wire is not feeding, it is usually caused by inadequate drive roll pressure or a blockage in the contact tip or liner. Check the drive rolls and contact tip before moving on to the liner, which takes more time and effort to check and replace.
If a faulty feeder relay is the cause, consult the feeder manufacturer for information on correcting the problem. A broken control lead or a poor adapter connection will require you to test and replace the leads and/or contact pins. Some guns feature a spare set of control leads that can be used to correct the problem. With others, it may be necessary to replace the entire cable.
Contact tip burnback — While burnback (see photo) will occur from time to time even when there isn't anything wrong with your gun and consumables, it could also be caused by improper equipment set-up. Be sure to check the following factors if you experience an increase in your contact tip burn back rates.
Improper tip recess and improper wire stick out can cause increased burnback frequency. In the case of incorrect tip recess (or stick out), you will need to install a nozzle and tip combination with a different recess. Similarly, adjusting the distance between the gun and the work piece (tip-to-work distance) will resolve burnback problems associated with wire stick out.
A faulty work lead/ground is another possible cause of burnback. Check and possibly replace the electrical connections and cables to ensure a faulty work lead/ground will not cause any further burnback.
Erratic wire feeding, a problem with several possible causes, is a frequent source of burnback. See the section below for information on correcting erratic wire feeding.
Erratic wire feeding — Erratic wire feeding simply means that the wire is not feeding from the gun at a consistent rate. This problem is usually caused by the liner, the drive rolls or the contact tip.
A worn out or kinked liner, or build-up of debris, filings, dirt and other foreign material inside the liner, the wrong size liner and gaps at the liner junctions caused by an improperly trimmed liner can all cause the wire to feed erratically. In each case, the liner will likely need to be replaced and properly trimmed so that it fits as tight as possible to the other components.
Improper drive roll size, worn out drive rolls and improper drive roll tension are also potential causes of erratic wire feeding. Replace worn out drive rolls or those of the wrong size with correctly sized and tensioned drive rolls.
Another common cause of erratic wire feeding is a contact tip that is worn out or the wrong size for the wire being used. If you suspect the contact tip is causing the wire to feed erratically, it is best to replace the tip.
