How To Judge Hot Runner Thermocouple Failure Without Disassembling The Mold

Frequent mould disassembly to inspect thermocouples will result in significant delay and production loss in actual manufacturing. Gaining proficiency in evaluating thermocouple failure using temperature controller data, moulding product flaws, and operational phenomena will enable speedy fault detection without disassembling the mould, enable quick repair, and shorten production halt times.

Check the temperature controller's display state first. If the temperature is constantly stuck at a particular value and does not rise with heating, it can be determined that the probe is ageing and insensitive or that the installation gap is too large; if the display shows an over-temperature alarm instantly or the temperature rises out of control, it is suspected of a short circuit; if the display shows a low temperature alarm and cannot be heated normally, it is primarily thermocouple open circuit or lead insulation damage.

Second, consider the flaws in the plastic section. Regular black spots and carbonisation on the product are primarily caused by thermocouple drift, which overheats the runner; persistent short shots, cold material lines, and poor weld lines are caused by false low temperature feedback and insufficient actual heating; and uneven weight and size of multi-cavity products are caused by the inconsistent ageing drift of each zone thermocouple.

Third, use the logic of heating operations. The controller either does not increase heating power when the set temperature is raised or the temperature continuously decreases after heating ceases, which is anomalous feedback brought on by thermocouple failure. Combining the aforementioned three techniques allows maintenance staff to precisely identify the location and type of faulty thermocouple without disassembling the mould, schedule targeted replacement and calibration, significantly reduce troubleshooting time, and minimise production loss from blind mould disassembly.