Definition
A direct current (DC) arc welding setup in which the workpiece is connected to the negative terminal and the electrode is connected to the positive terminal of the welding power source, causing electrons to flow from the work to the electrode. This arrangement concentrates more heat at the electrode than at the work, producing shallower penetration but a wider, smoother weld bead, and is well suited to thin materials and certain aluminum and magnesium alloys.
Plain English
A way of wiring up a DC welder so the metal being welded is on the negative side and the welding rod is on the positive side. This puts more heat into the rod and less into the metal, which works better for thinner sheet and certain non-ferrous metals.
Context Anchor
Seen in aircraft maintenance welding procedures, especially when selecting welding machine settings for metal repair.
Derivation
Polarity comes from the Latin polus meaning end or pole, referring here to the two terminals of the DC power source. Reverse simply indicates the wiring is opposite to the older standard arrangement (straight polarity), where the electrode was negative and the work was positive.
Why Pilots Care
Aircraft structures often involve thin-gauge sheet and aluminum components where burn-through is a real risk. Choosing the correct polarity is part of producing an airworthy weld, and using the wrong setup can lead to weak joints, excessive penetration, or contaminated welds that fail inspection.
Analogy
It is like connecting a battery-powered device with the positive and negative leads in a specific way. The connections matter because the electrical flow affects how the equipment behaves.
Intuition Check
Reverse does not mean the weld is made backward or in the opposite travel direction. It means the positive and negative electrical connections are arranged opposite to straight polarity.
Example Sentence 1
The technician switched the machine to reverse polarity welding before joining the thin aluminum panels to reduce the chance of burn-through.
Example Sentence 2
Reverse polarity welding produced a narrower bead suitable for joining the thicker spar sections.