How to correctly use thread screws self tapping screws?

One or three contour thread forming 1, make sure the connection complete; 2, overcome friction increased; 3, reduces driving torque. And complete the second thread the projection plane 1, product consistency; 2, improve connection. Third, reduce connectivity costs To reduce connectivity costs is to remove inefficient processes and unnecessary parts. When triangle self tapping screws into the object, the automatic thread suitable for the line, expensive automatic tapping device and tapping operations are no longer needed.