Helix angle 35° & 45° P6E-4 Flute of Square end mills basic HRC is 55 4 Flute Square End Mills Helix angle 45 degrees with more cutting surface, polished the surface. P6E-4 flute Square end mills with better hardness to be applicable for side milling process, end user choose helix angle 45° for speed molding which combine hardness、 side milling and easy chip deposal with common use.