This standard specifies the shape, size, screw end and bottom hole diameter of plastic (nylon) before tapping for self-tapping screws with thread specifications of NST 3 to NST 7. This standard applies to self-tapping screw threads screwed into plastic (nylon) bottom holes.
QC/T 713-2004 history
2004QC/T 713-2004 Tapping screws thread for plastic(nylon)