Die-temperature management during the run: thermal profiling in plain English

A shift-by-shift trend on one defined point on the die, taken at a defined moment in the cycle, with the same tool, is more useful than a spot-check with three different tools that disagree by 80°C. The absolute temperature has known error bars from the measurement chain. The shift-over-shift change is real even if the absolute is wrong. A trace that has been reading 380°C at the back corner of the impression ten seconds after lubricant spray for three weeks, and now reads 430°C in the same spot at the same moment, is telling you the cooling is drifting or the lubricant is failing. Investigate the change. Do not investigate the absolute.

This is why one tool, one point, one moment in the cycle, logged every shift, is worth more than a thermal camera survey done once a quarter. The camera is a useful diagnostic when something is already wrong. The shift log catches the drift before something is wrong.

Heat-treat shops that audit to AIAG CQI-9 are running their pyrometry against AMS 2750G, the current edition of the SAE aerospace pyrometry standard. AMS 2750G specifies the calibration intervals, the system accuracy test (SAT) procedure, and the temperature uniformity survey (TUS) procedure that production heat-treat equipment is held to. A nitriding furnace running parts for an aerospace forge die operates under AMS 2750G discipline. A forge shop's die-side IR gun does not. The point is not that the gun on the production floor needs to meet aerospace pyrometry calibration. The point is that the gap between a heat-treat shop's calibrated thermocouples and the operator's handheld IR gun is large, and treating an IR reading as ground truth ignores the gap. The production-floor instruments still need a defined internal calibration interval, even if it is shop-internal. AMS 2750G is the reference document if your tooling engineer or quality team wants to know what good pyrometry looks like.