| Resistance or Friction welding are two welding | | | | When you have metals that are under a lot of |
| processes that fit into a category of processes | | | | pressure and heat you will be working with |
| that works with a workpiece that is moving and | | | | thermoplastics. You can join metal and plastic |
| another piece that remains stationary. In the | | | | together. A good example of this is when they |
| process heat is generated through friction as the | | | | use friction welding to join the pins of eyeglass |
| two pieces come together and an "upset" (a | | | | frames to the rest of the frame. |
| lateral force) displaces and fuses these materials. | | | | There are several welding techniques that use |
| Friction welding is generally used with | | | | friction welding. Spin or inertia welding has two |
| thermoplastics and other metals and is used a lot | | | | "chucks" that hold the metal with one stationary |
| in the aviation and automotive industries. In friction | | | | and the other that rotates. The piece that the |
| welding there is no melting and the heat is | | | | welder wants to weld is put on the rotating chuck |
| directed to the weld interface. This creates a | | | | and a flywheel is added so that it will have a |
| small heat zone. Also, as the friction is happening it | | | | specific weight. They then spin the piece they |
| cleans the surface of the materials to be welded | | | | want to weld at a high speed, then remove the |
| so the welder does not have to prepare the | | | | motor and the pieces are put under pressure and |
| surfaces before welding. | | | | forced together. The pieces "set" once the |
| This method of welding also has several | | | | spinning has stopped and the pieces have cooled |
| advantages. The metal that is used has small | | | | down from the friction. |
| pieces of "plastic" metal that is forced out of the | | | | Linear friction welding is like spin welding but |
| area where the friction is happening. This metal | | | | instead of spinning it oscillates in a lateral motion. |
| called "flash" comes out in ripples and seems to | | | | The speed that the welder uses is lower and the |
| carry away the dirt or the debris that would | | | | pieces are kept under pressure throughout the |
| normally occur when doing welding. | | | | entire process. In order to do this type of welding |
| Two different types of metals can also be joined | | | | the industry needs a more complex machine |
| using this method. An example of this is in the | | | | which is a bit more expensive, but it also allows |
| aerospace industry where they use friction | | | | any two shapes to be joined. |
| welding to bring together aluminum and | | | | Thermoplastics have other methods that they |
| high-strength steel. This can only be done in | | | | use for friction welding. In Orbital friction welding |
| friction welding because they are two different | | | | an orbital motion is made by the moving part |
| types of metal. The nuclear industry also uses this | | | | (similar to the spinning friction process) and it |
| method to do cooper and steel joints that are | | | | rotates in line with a smaller circle than the joint. |
| used in the reactor's cooling systems. | | | | |