resistance welding definition
History of welding technology
In ancient times, metal welding was done in the form of forge welding (metals heated up to melting point are pressed together) and brazing (weld using alloy of low melting point). With the advent of electricity, welding technology advanced remarkably; namely, resistance welding, arc welding and gas welding were invented in the end of 19th century. Thereafter, various welding technologies such as ultrasonic, friction, electron beam, plasma, laser welding have been invented.
Though we have very little chance to experience the welding technology, it is applied broadly in a variety of industries and contributed their growth.
Principle of resistance welding
Resistance welding is conducted as follows: Apply force and current through electrodes contacted metal parts to be welded; and resistance heat is generated at the interface of metal parts and makes a nugget, resulting in melt joint. Though a large current flows, there is no danger of an electric shock because only low voltage is impressed.
Features of resistance welding
Followings feature in resistance welding:
- No flux such as solder is necessary, so welded parts can be easily recycled. Spatter and ultraviolet ray are most unlikely to be generated; consequently, clean and neat worksite is realized.
- Easy operation as only pressing buttons facilitates process automation and does not require trained skills unlike arc welding and gas welding.
- As this welding is performed efficiently in a short period of time, it is suited for a high-volumes production of low-cost products.
- Since welding is done in short time duration, it gives less heat-affected area on workpieces, resulting in beautiful appearance with less indentation.
- Electric facility is required in some cases due to use of large current. Optimum welding parameters must be figured out before actual welding since those parameters depend on material and thickness of parts to be welded. welding condition setting must be prepared.
- Visual inspection is difficult because welded portion cannot be checked from the outside.
Source: AMANDA MIYACHI