在微加工操作中，去除少量材料，产生非常小的切削力。直径小于1mm的微型立铣刀的刀具寿命短且不可预测。当这些工具失效时，它们的轴就断了。在加工操作过程中，操作员无法通过声音或目视检查来检测刀具破损。本文通过观察刀具尖端的扫描电镜（SEM）图像和声发射活动，评估了微立铣刀的推力特性，解释了微立铣刀的刀具破损机理，即磨损诱导应力（WIS）。

In micro-machining operations, a small amount of material is removed and very small cutting forces are created. Micro-end mills with less than 1-mm diameter have a short and unpredictable tool life. When these tools fail their shafts are broken. An operator cannot detect tool breakage from the sound or by a visual inspection during the machining operation. In this paper, the tool-breakage mechanism of micro-end mills, wear-induced stress (WIS), is explained by evaluating the thrust direction cutting force characteristics, by inspecting scanning electron microscope (SEM) images of tool tips and acoustic emission activity.