Extrusion
Extrusion is a process in engineering, which involves forcing a metal through a die at high pressure in order to acquire a desired profile. The high pressure is developed by hydraulic or mechanical presses.
The material to be extruded is usually heated to a higher temperature. Extrusion can also be carried out at normal temperature. The heated material is pushed through a die. A ram is used to forcibly push the material through the die.
Many materials such as Metal, plastic, food stuffs, glass, etc. can be extruded. Squeezing a tube of tooth paste is an example of extrusion.
Extrusion is advantageous over other forms of manufacturing as the material extruded is subject to very limited tensile stress.
Hot Extrusion
If the extrusion is carried out above the recrystallization temperature, the process is known as hot extrusion.
Cold Extrusion
If the extrusion is carried out below the recrystallization temperature, it is known as cold extrusion.
The products of extrusion may not have the desired finishing. The surfaces may have to be smoothened separately.