for mechanical engineering: Welding Processes

Friday, February 8, 2013

Welding Processes

The manufacture of virtually all sophisticated modern products involves joining together many individual components. Where a permanent join is required, welding is often a good option. Other possible processes such as brazing, soldering, and use of adhesives will are considered in the Design module.

Welding processes can be split into two broad categories:

Fusion processes

The surfaces of two components to be joined are cleaned, placed close together and heated while being protected from oxidation. A pool of molten metal forms and connects the components, a filler rod may be used to add metal to the joint.
This category covers a very wide range of processes, some of which are considered in more detail later

Solid phase processes

The metals to be joined do not melt, they are heated, usually by friction heating generated by sliding the parts together under a normal load, this softens the metals and removes surface contamination. The sliding is then stopped, the normal load is increased and the two surfaces join together.
Friction welding is the main process in this class and is widely used to join axisymmetric components in two different types of steels. Examples include engine valves where a heat resistant alloy head is required, but a steel that will slide well in the guide is needed for the stem.