How Mold Cooling System Interacts With Hot Runner Thermocouple Reading

The arrangement of the cooling water channels will immediately impact the ambient temperature surrounding the thermocouple probe, causing a variance in the temperature measurement reading. The hot runner heating system and the mould cooling water channel system are mutually restricted and related. The distance between the water channel and the thermocouple mounting hole is often overlooked by mould designers in favour of quick cavity cooling. This leads to long-term low false temperature feedback, which significantly disrupts the hot runner's regular temperature management.

Typically, cooling water channels with low circulating water temperature and quick heat dissipation are positioned around the mould plate and cavity. The low-temperature cold radiation will continually remove the probe's heat if the thermocouple embedding hole is too close to the water channel, resulting in a feedback temperature that is much lower than the melt runner's actual temperature. While the reported temperature is consistently within the typical set range, the temperature controller misjudges that the heating is insufficient and repeatedly increases power, leading to actual overheating of the runner, material degradation, and carbonisation.

The cooling medium is nearer the nozzle tip runner in water-cooled hot runner nozzles. The accuracy of the cold junction compensation will be destroyed if the thermocouple is installed in an inappropriate position because water cooling will affect the cold end and create additional temperature difference interference. The product quality will vary in the winter and summer because to the regular drift of thermocouple readings caused by seasonal cooling water temperature changes.

A reasonable mould design must prevent direct cold radiation, isolate heat transfer with heat insulation gaskets where needed, and maintain a safe distance between cooling water channels and thermocouple attachment holes. Optimise the thermocouple's embedding location, place it in the core heating region away from the cooling zone, and make sure the probe actually detects the melt runner temperature rather than the cooling-affected ambient temperature. It is possible to optimise mould design from the ground up and remove temperature measurement variance brought on by cooling interference by comprehending the interaction law between the cooling system and thermocouple reading.