It is obvious that the machining marks in both cases take the form of a spiral.

很明显在这两种情况下机加工痕迹都是螺线形式。

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Firstly, it produces a superior surface finish with all machining marks being removed from the surface.

首先，它通过去除所有机加工痕迹能产生较好的表面光洁度。

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The resulting machining marks are, therefore, a helix having a very small pitch, which is equal to the feed. Consequently, the machined surface is always cylindrical.

所以，由此产生的机加工痕迹是一条具有很小节距的螺旋线，该节距等于进给。因此机加工表面始终是圆柱形的。

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