Thread Mill Helix Angle for HRC65 Steel: How Helix Angle Affects Thread Milling Performance
Last month, a precision stamping die client in Stuttgart, Germany reached out to us with an urgent production bottleneck. They were threading M3×0.5 holes in 1.2379/D2 cold-work die steel hardened to HRC 64–66. Using off-the-shelf 45° high-helix thread mills, their tools failed almost immediately. By the second hole, the neck suffered microscopic fatigue fractures or