Unavoidable mechanical collision during mold disassembly, grinding maintenance, transportation and daily workshop handling is one of top physical damage causes for bayonet and embedded thermocouple equipped on all mainstream brand hot runner including Männer medical customized series and domestic packaging multi-cavity hot runner; invisible internal damage formed by instantaneous impact often does not break outer sheath immediately but gradually evolves into insulation degradation and intermittent signal failure after short-term production startup. Direct hard collision on exposed thermocouple probe bends mineral-insulated seamless sheath and squeezes internal compact magnesia insulation powder to generate inner gap and cavity; air entering inside destroys original tight insulation structure, high-temperature steam and corrosive plastic volatile gas permeate into gap after installation and gradually erode core alloy wire, triggering irregular insulation resistance drop and occasional short-circuit alarm after one to two months continuous production.
Bayonet head collision deformation damages original dimensional tolerance, deformed bayonet cannot keep tight compression after inserting mounting hole and forms persistent loose contact gap between sensing tip and hot runner metal surface, bringing long-term slow measurement drift. Outer connecting wire suffers extrusion and pulling impact during mold hoisting maintenance, internal core wire partially fractures inside insulation coating to form hidden semi-open circuit; such latent fault displays normal reading under static cold mold state but appears sudden temperature loss or sharp jumping after hot runner heating expansion and wire thermal stretching.
Standardized mold maintenance workshop sets fixed thermocouple protection regulation: before mold split overhaul, exposed external thermocouple is wrapped with high-temperature resistant foam protective sleeve to avoid direct collision from tool and mold component; customized protruding probe thermocouple is temporarily detached and stored in special anti-collision storage box during long-distance mold transport. Once collision accident happens on-site, maintenance personnel implement full appearance inspection and multimeter continuity test for impacted thermocouple, discard products with invisible inner damage risk directly instead of continuing installation on production hot runner. Effective anti-collision management greatly reduces abnormal thermocouple scrap rate induced by careless mechanical impact in injection workshop.
