Standardized installation procedure directly decides thermocouple measuring accuracy and long-term service stability; improper assembly including insufficient preload, wrong insertion depth and disordered wiring accounts for nearly 65% of early-stage thermocouple abnormal faults during hot runner trial run and mass production. Before formal installation, maintenance operators firstly need to clean reserved mounting holes on hot runner nozzle and manifold thoroughly to remove residual plastic carbon, rust and metal burr; leftover dirt blocks tight contact between probe tip and measured metal surface and causes large measuring error after heating up. For mainstream spring bayonet thermocouple matching Husky, YUDO and domestic hot runner brands, reserved hole depth reserves 1–2mm compression allowance for built-in spring; excessive insertion compresses spring into permanent deformation while shallow assembly leaves loose clearance leading to intermittent separation under thermal expansion and cold contraction.
When installing manifold embedded grounded thermocouple, operators push armored probe horizontally into preprocessed manifold holes until sheath outer wall fully fits inner hole surface without vacant gap; excessive knocking during installation easily deforms seamless sheath and damages inner compacted magnesia insulation layer to trigger hidden short-circuit risk. Clip-on buckle thermocouple fixed outside nozzle heating rings requires uniform clamping force to avoid slipping under long-time mold vibration; over-tightened metal buckle squeezes outer wire coating and causes insulation cracking under high ambient temperature.
Wiring specification is another core installation control point. Thermocouple positive and negative core wires cannot be reversed when connecting with controller terminal blocks; wrong polarity leads to continuously falling displayed temperature value while hot runner keeps uninterrupted heating and causes melt overflow burr defects. Double-layer shielded cable needs single-end grounding at controller terminal side instead of double-side grounding on both equipment and control box; double grounding forms ground loop and induces new alternating current signal interference resulting in random temperature fluctuation. All connecting wires inside mold wiring grooves are fixed by high-temperature plastic wire clips to prevent being extruded and cut during repeated mold clamping movement.
After finishing all assembly work, cold-state inspection and segmented temperature rising test become necessary final verification steps. Operators switch on temperature controller under cold mold status and check whether displayed temperature matches ambient room temperature roughly; obvious deviation indicates installation defect needing secondary disassembly and readjustment. Then implement segmented step heating instead of one-time rapid temperature rise to reduce instantaneous thermal shock damage to newly installed probes; observe real-time temperature change curve continuously during heating process, stable and smooth data proves qualified installation while irregular jumping points need targeted troubleshooting of contact tightness and wiring status.
