Posted by Robert Hernandez on Sep 8th 2026
| Term | Definition |
|---|---|
| Radiograph | An image on film produced by X rays. |
| Range switch | The coarse adjustment lever on a welding machine. |
| Rated Load | The specifications of a power source in regards to amperage and voltage. |
| Rated output current | The maximum current flow a welding machine can produce. |
| Reading the bead | The process of visually inspecting the weld bead to determine whether the weld was made properly. |
| Regulator | A mechanical device for accurately controlling the pressure and flow of gases employed in welding or cutting. |
| Rectified current | Alternating current that has been made to flow in one direction only through use of a rectifier. |
| Rectifier | An electronic device (such as a diode) that acts like a one-way valve as current flows through it. It converts AC current to DC current. |
| Reducing gas | A gas that removes oxygen from the atmosphere by combining with oxygen. |
| Reference line | The horizontal line drawn on a welding symbol. All information about the weld is positioned above or below this line. |
| Reinforcement of weld | Weld metal on the face of the weld in excess of that required for the size of the weld, for the purposes of adding strength. |
| Remote contactor control | A receptacle on the welding machine where the wire feed control mechanism is plugged in. |
| Repeatability | The term used to describe a robot’s ability to make welds in the same place, and of the same quality, on part after part in production. |
| Residual stress | The stress that remains in a body (such as a weldment) after the external forces or thermal gradients have been removed. |
| Resistance | The property of a material that causes the flow of current in a circuit to be retarded. |
| Resistance seam welding | (RSEW) A process that usually uses a round, rotating (wheel) electrode to make a continuous seam. A seam can also be formed with overlapping spot welds. |
| Resistance Spot Welding (RSW) |
A process joining two pieces of metal by passing current between electrodes placed on opposite sides of the pieces to be welded. There is no arc; rather it is the resistance of the metal to the current flow that causes the fusion. |
| Resistance welding | A process that uses the resistance of metals to electrical flow as a source of heat for welding. |
| Restarting the arc | Establishing a new arc after changing electrodes, or after losing the arc due to faulty welding technique. |
| Restricted nozzle | In plasma arc welding (PAW) the nozzle through which orifice gas flows to form the plasma. |
| Reverse polarity | An electrode positive anode. Referring to DC current and causing electrons to flow from the base metal to the electrode. |
| Robot | A device that uses a computer program to direct its movement as it completes a series of welds or other operations. |
| Robot cell | A three-dimensional space enclosing the robot and its working area, usually fenced off for safety of employees. |
| Robot controller | The computer and associated devices that direct a robot in carrying out the program developed for it. |
| Robotic welding system | An industrial production operation using one or more robots, controllers, positioners, and other equipment to make a programmed series of welds on a weldment. |
| Robotic welding work station | The location where a single robotic welder makes a specific set of welds. |
| Rockwell C hardness test | A hardness test generally used for hard materials. The test utilizes a special piece of equipment to force a pointed diamond into the metal surface. |
| Rod ID | Patented device used to identify the contents of a Rod Guard welding wire and rod storage container. Rod ID caps simply snap onto a Rod Guard container, and the handy printed label allows operators to mark the cap with date, wire size, and type for easy reference. Rod caps also have a leash chain that allows you to hang the welding rod’s heat numbers, mil specs, manufacturer certs, and SDS documents. |
| Root bend | A test performed by bending a weld sample with the root of the weld on the outside of the bend. |
| Root face | The distance from the root of the joint to the point where the bevel angle begins. |
| Root of weld | That part of a weld farthest from the application of weld heat and/or filler metal side. |
| Root opening | The distance between the two pieces at the root of the weld. |
| Root pass | The first weld pass made into the root of the joint. |
| Root penetration | The depth to which weld metal extends into the root of a weld joint. |
| Root reinforcement | The distance that the penetration projects from the root side of the joint. |
| Rosin | A substance used as a welding flux. It is derived from the sap of pine trees. |
| Rosin fluxes | Those fluxes that are noncorrosive, and are recommended on electrical and electronic parts. |
| Running a bead | The process of making a weld bead. |
| RMS | Root Mean Square; the “effective” values of measured amperage. |
| RWMA | The Resistance Welder Manufacturers Association. |
