Definition
A direct-current arc welding configuration in which the electrode is connected to the positive terminal of the power source and the workpiece to the negative terminal. Electrons flow from the workpiece to the electrode, concentrating heat at the electrode tip and producing a shallower, wider weld penetration with strong cleaning action on the metal surface. Also called DCEP (direct current electrode positive).
Plain English
A type of arc welding where the welding rod is hooked up as the positive side and the metal being welded is the negative side. This puts more heat into the rod and less into the metal, which gives a wide, shallow weld and helps clean the surface as it welds.
Context Anchor
Seen in aircraft maintenance welding instructions and welder setup procedures when selecting the correct lead connections for a repair.
Derivation
The term reverses the older convention. In early DC welding, 'straight polarity' was defined as electrode-negative. 'Reverse polarity' simply meant flipping the leads so the electrode became positive. The names stuck even after modern terminology (DCEP/DCEN) replaced them.
Why Pilots Care
Produces stronger, deeper welds on load-bearing aircraft parts when performed correctly.
Intuition Check
Reverse-polarity welding does not mean welding in the opposite direction. It means the electrical connections are set with the electrode positive and the work negative.
Example Sentence 1
The mechanic switched the machine to reverse-polarity welding before starting work on the aluminum fuel tank repair.
Example Sentence 2
Using reverse polarity on the thin fuselage patch helped prevent burn-through while achieving full penetration.