Inspection cadence: what to look for at 1K, 10K, 50K, and 100K hits

A die that reaches 100K hits on H13 plus nitride is a sign the process is well-tuned. Most forge dies do not reach 100K without at least one repair cycle, and many do not reach it at all. The inspection at 100K is end-of-life accounting. The decision is no longer pull-or-run on this build. The decision is which repair cycle the die enters next, or whether it goes to scrap.

Normal at 100K. Cumulative wear in every critical feature: flash-land drift of 0.05-0.15 mm or more, internal-radii rounding of 0.10-0.20 mm, surface roughness materially higher than build. The heat-check network is deeper than at 50K and may show shallow spalling in the hottest regions, where the network has eroded into a textured surface rather than a crack pattern. Lube pattern may show drift from the engineered map because the impression geometry has changed enough that the spray is no longer hitting the original target.

Red flag at 100K. Anything new propagating fast. A crack that was 2 mm at the 75K inspection and is 4 mm at 100K is propagating, and on a die at end of life it is not going to slow down. A region of spalling that was not there at 75K means the diffusion zone is gone in that spot and the substrate is wearing directly. A part dimension drifting visibly out of tolerance across the last 5K hits means the die is done. Pull the die. Capture the failure mode photographically for the next die build, because the failure mode at 100K is the failure mode that will set the life of the next die unless something in the design or process changes.