Cooling performance can decline even when measured flow remains acceptable. Scale and deposits add thermal resistance between the mold and coolant, while corrosion debris can migrate and restrict smaller passages or valves.
A gradual increase in mold temperature, outlet temperature, pump pressure, or cycle time may indicate fouling. Water chemistry, filter condition, deposit samples, and maintenance history should be reviewed. Comparing a cleaned circuit with an unchanged circuit can reveal heat-transfer loss that flow readings alone miss.
Water treatment and cleaning must be compatible with aluminum, steel, copper alloys, seals, and connected equipment. Aggressive chemicals can remove deposits while attacking the tool. Closed-loop quality, filtration, corrosion control, and scheduled inspection should be managed as part of process stability.