US Patent 7832615 Joining method and joining apparatus

A metal plating applied on a joining portion of a first metal member is heated before a rotating tool under rotation being pressed against a second metal member. Herein, the rotating tool under rotation starts being pressed against the second metal member when the metal plating is heated at least up to a specified temperature that is high enough to make the metal plating in a softened solid state. Thereby, a properly-high joining strength can be provided in a frictional joining of a metal member with a metal plating thereon and another metal member.