A multi-cavity tool may form uniformly but cool unevenly. Cavities nearest the coolant inlet, manifold, fan, or heavy tool mass can follow a different thermal cycle from remote cavities. One global mold-temperature reading hides the difference.
Cavity surface temperatures and part temperatures should be compared at the same cycle point. Cooling flow, channel routing, tool contact, insert fit, and local wall thickness must be considered. A cavity that starts hotter every cycle may have a hydraulic problem; a cavity that becomes hotter only during a run may have insufficient local capacity.
Circuits should be balanced or separated where independent control is necessary. Release timing should not be set by the fastest cavity if another remains too soft. Cavity-specific data should be retained when dimensional capability is evaluated.