Author: Bob Page
Eliminate High Resistance Areas
Poor arc quality can be caused by a high resistance which produces a “hot spot” due to undersized welding cables or even correctly sized cables that have cuts or splices. If you have a poor arc, double check that the weld cables are sized correctly, in length and diameter, for the amperage output and duty cycle required. If they are undersized, replace them. If the cables are correctly sized but arc quality is poor, weld for 10 or 20 minutes, stop, and feel or look for (with a Forward Looking Infrared camera) hot spots on the weld cable.
Any hot spot will cause a voltage drop and needs to be repaired or replaced, whatever the case may be.
High resistance hot spots are also frequently found at loose lug terminals or are hidden within the cover of Dinse and Tweeco connectors where the connection between the welding cable and connector has been compromised. Cheap spring loaded ground clamps often perform poorly (even when they aren’t broken) because of the small surface contact area with the workpiece. Also, when the ground cable inevitably becomes frayed at the clamp connection, high resistance and heat will result along with a degraded arc. And don’t forget to check for a tight weld cable connection to the wire feeder conductor block.
See the chart below for proper cable sizing.