What is external force?

What is external force? What types of external forces are metals subjected to during deformation? The metal placed on the hammer anvil was hit by the chain head, causing a change in its original shape. We call the hammering force an external force. There are three types of external forces that metal undergoes during deformation: (1) Force: The force is the impact force (impact force or static pressure) transmitted to the metal billet by forging equipment or with the help of tools or molds. The force is the fundamental reason for the deformation of gold shavings. (2) Reaction force: When forging metal, tools or molds will generate pressure on the metal, which is the force that prevents the flow of metal, known as reaction force. (3) Friction: When a metal undergoes deformation under external forces, the force generated by the friction between the metal and the surface of the mold is called friction. Its size is related to the surface roughness of the anvil surface and the mold. The rougher the surface roughness of the anvil, the greater the frictional force.