| A | B |
|---|
| Weld | a localized coalescence |
| Forged Welding | Also known as hammer welding, A forge was used to heat metal, and the ends of the iron were hammered together |
| Resistance Welding | Faster, more reliable |
| Fusion Welding | replaced riveting |
| Coalescence | the fusion of the grain structure of the materials being welded |
| Early metal-joining methods | Sand molds for casting and Pouring molten metal between two pieces of metal |
| Manual | the welder manipulates the process |
| Semiautomatic | filler is added automatically |
| Machine | done mechanically under observation |
| Automatic | no interaction with the operator |
| Automated | performed repeatedly by a robot programmed for multiple tasks |
