在本试验参数范围内选取切削参数时，切削速度、进给量取中值有利，切削深度取小值有利。

At the range of the testing parameters it is of advantage to select middle value of feedrate and cutting speed, and smaller value of cutting depth.

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此外，他们认为，对于攻丝存在一个临界切削厚度(螺纹深度)值，在临界切削厚度的范围内，攻丝能降低攻丝扭矩。

In addition, they believe, for tapping there exists a critical cutting thickness (thread depth) value of the critical cutting thickness within the tapping can reduce the tapping torque.

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