The surface material under the condition of half melting is compelled to flow to the reverse direction, that is none restraint free surface. Thus, the grinding triturate is formed.

由于该区内材料产生了巨大的单向反弹力，迫使已处于半熔化状态的表面材料向压力相反方向即无约束的自由表面流动，从而使磨屑形成。