Forge die building: why this course exists

The cavity is where the failure mode is decided. Minimum internal radius, draft angle, flash land thickness and width, gutter depth, and gate placement set the stress field on every cycle. A sharp internal corner runs a stress concentration factor (Kt) of 3 to 5 in real geometry. Add a brittle compound layer at that corner and the die initiates a crack on the first thermal cycle. Lesson 3 covers the design rules that keep the geometry from sabotaging the rest of the build.