Form Clearance (cF) is the radial depth of involute profile beyond the depth of engagement with the matingpart.
齿形裕度：齿形裕度(cF)是相互配合的内、外花键的渐开线齿廓超过结合部分的径向距离。
2
To make the part interchangeable, each individual part must be made to a size that will fit the matingpart in the correct way.
为了使零件能够互换，每个零件作出的大小必须能准确地适用于与其匹配的零件。
3
The thread length of the stud provides sufficient thread engagement with the matingpart while allowing maximum play along the axis of the sleeve, preventing jacking.