During the process of spinning triangular heteroclite dacron fibres from polyester garbage, there are factors that may affect the hetercliteness of the intersecting surface of the fibres thus spun.

It is proved that the intersecting line of the two curved surface is space curve, and the equation is quartic implicit function with one unknown.

The method for manufacturing this surface-coated cutting insert includes: forming a cutting edge at the intersecting edge line region;