我查了一下維京百科 (From wikipedia) 發現了英文版本的說明更可以貼切的讓大家清楚。
Friction drilling is a method of making holes in metal in which the material is pushed out of the way with the aid of heat from friction. The process is also called thermal drilling, flow drilling, form drilling, or friction stir drilling.
Friction drilling is commonly used on bicycle frames, heat exchangers, and to create holes for mounting bearings.
(above information from wikipedia )