Nc reduces the amount of non - chip - producing time by selecting speeds and feeds , making rapid moves between surfaces to be cut , using automatic fixtures , automatic tool changing , controlling the coolant , in - process gauging , and loading and unloading the part Nc (產(chǎn)品簡稱)通過選擇速率,高速轉(zhuǎn)變切割面,自動改變工具,控制冷卻劑,減少了這些不必要的非工作時間,工作中劃定規(guī)格,和裝卸降低了這些不必要的非制造時間。