Intro
33%
Die change-out timing: when to push, when to pull
A working die is always asking one question: keep running, or pull now. The answer lives in scrap-rate trend, wear-progression rate, and the asymmetry between a planned change-out and a catastrophic in-press failure.
A closed-die forge shop is running a connecting-rod job on H13 dies. The day-shift inspector flags a 2 mm crack propagating out of the heat-check network at 72K hits. Scrap rate over the last 5K hits has climbed from a steady 0.5% to 3.1%. The die is still producing parts inside the dimensional band on average. Production supervisor wants to push to the end of the week (two more shifts, about 4K more hits) and pull the die on the scheduled Saturday morning change. Maintenance supervisor wants to pull on the next shift change tonight. Both have an argument. Only one is right.
This lesson is about that argument and why it is almost always settled the same way.