Welding in the joining process
Welding is the permanent joining of structures or devices made of plastic or metal. The metal parts are brought to a plastic, i.e. dough-like, state by heating. They are then joined by applying sufficient force without the use of a bonding agent. A small volume is plasticised only at the plastic/metal interface. Heat sources can vary. The most common is electric resistance welding, i.e. resistance welding.
Types of welding:
- water gas,
- electric resistance,
- spark butt,
Depending on the method, pressure is applied first, followed by heating or in reverse order. Metals and ceramics can also be joined.
Electrical resistance welding involves joining metals based on their natural properties, i.e. electrical resistance. Heat is released by means of current and pressure from the electrodes. The metal is melted and the parts are joined. No third metal, i.e. a filler metal, is needed for welding. Electric resistance welding is, among other things, used to join sections or sheets. The quality of the joint depends on the clamping force as well as the amount of heat. In electric resistance welding, the most commonly used methods are spot, hump, butt and line welding. Many materials can be joined by electric resistance welding. Welding is widely used in industry. The following materials are welded: nickel, aluminium, titanium, copper, ferrous and non-ferrous metals.
Friction welding is also quite popular. In this method, the temperature is generated by surface friction. One component is immobilised while the other is set in motion. The phenomenon of particle diffusion and also creep is important. Energy is transformed into heat. A corresponding plasticity is created and the objects become immobile. Friction welding is a relatively new method compared to other welding methods. This method is used in high-volume productions, i.e. aluminium wheels, tools, automotive parts.