Commonly used indexable insert blades are regular triangle, quadrilateral, pentagon, convex triangle, circle and rhombus. The diameter of the inscribed circle of the blade profile is the basic parameter of the blade, and its size (mm) series is 5.56, 6.35, 9.52, 12.70, 15.88, 19.05, 25.4…. Some have holes in the center and some have not; some have no or different relief angles; some have no chip breakers, and some have chip breakers on one or both sides.