Hot runner manifold keeps continuous high-temperature state between 280~380℃ during full-day mass production of Husky and domestic multi-cavity packaging molds, far-infrared thermal radiation spreads outward continuously and easily deteriorates nearby exposed unprotected thermocouple terminal block without heat insulation shielding, triggering terminal oxidation, plastic base aging and gradual measuring instability hidden trouble. Plastic terminal seat made of ordinary ABS or low-grade nylon material gradually softens, deforms and generates tiny crack under long-time continuous thermal radiation from manifold; cracked terminal base cannot fix metal wiring terminal firmly, positive-negative terminals shift position randomly under slight workshop vibration and produce intermittent poor contact fault. High ambient temperature around terminal block accelerates copper terminal oxidation speed remarkably, thick oxide layer accumulated on contact surface raises loop resistance and brings slow cumulative zero drift of thermocouple measuring data, which seriously disturbs closed-loop temperature adjustment accuracy of hot runner controller.
Standard protection solution installs high-temperature resistant mica insulation baffle and stainless steel heat shield between manifold high-temperature area and external terminal wiring region to block direct thermal radiation transmission; terminal block uniformly upgrades high-temperature resistant PBT or bakelite plastic base material capable of enduring long-term ambient temperature above 150℃. For terminal unavoidably arranged within short distance from high-temperature manifold, customize short-distance high-temperature extension wire to move terminal block outward away from radiation influence area. Many small mold manufacturers omit heat shielding configuration during early mold design to save accessory cost, resulting in terminal centralized aging failure within half a year after mold put into formal production and frequent monthly maintenance workload increase.
Quarterly fixed maintenance inspects aging deformation status of all terminal blocks near high-temperature manifold, replacing cracked and seriously oxidized components in advance before complete circuit breakdown occurs, reasonably extending average service cycle of external wiring terminal and reducing unplanned production halt loss induced by sudden terminal failure.
