Class 10000 and Class 1000 cleanroom medical injection molding workshops for syringes, test cartridges and implant parts impose strict dust-free, non-pollution and corrosion-proof requirements on hot runner thermocouples, requiring exclusive multi-layer protection measures covering material selection, structural sealing, wiring shielding and daily maintenance to avoid particulate contamination and metal ion precipitation that fail medical product biocompatibility tests.
Material protection is the first barrier of cleanroom thermocouple design. Ordinary 304 stainless steel sheaths are replaced with mirror-polished 316L medical-grade stainless steel or Inconel 600 alloy, which have extremely low heavy metal precipitation rate and smooth surfaces that do not absorb tiny plastic dust particles. Internal thermo wires adopt high-purity K-type chromel-alumel alloy without impurity elements; low-purity J-type iron wires are prohibited to prevent iron ion dissolution into molten medical PP and PEEK at high temperature. The magnesium oxide filling powder inside sealed sheaths must be medical high-purity grade without volatile organic compounds, avoiding toxic gas release if tiny pinholes form on the sheath surface. All raw materials must provide ISO10993 biocompatibility test reports before thermocouple production.
Integral seamless structural sealing protection eliminates dirt retention dead corners, the core cleanroom mandatory standard. Low-cost welded probes with tiny joint gaps are completely banned; medical dedicated thermocouples adopt one-piece seamless drawing molding technology, with all surface joints fully compacted and polished to Ra≤0.8μm mirror finish. No hidden gaps exist for plastic residue, dust or bacteria to accumulate, meeting daily cleanroom disinfection requirements. Unsealed bare wire thermocouples are forbidden, as exposed wires shed metal debris and absorb workshop dust, which will mix into disposable medical consumables and trigger safety hazards and product recalls.
Dust-free wiring protection targets extension cables and connectors. Fiberglass braided insulation that sheds micro fiber fragments is replaced with integrated seamless PTFE insulation without particle shedding. The outer shielding copper braid is wrapped with thin PTFE film to prevent copper powder from falling into the cleanroom air during wire bending. All multi-pin mold connectors adopt fully enclosed dust-proof and waterproof medical plastic shells with silicone sealing rings, blocking cleanroom dust and disinfection alcohol vapor from corroding internal signal pins. Thermocouple wiring channels inside molds are fully polished without burrs to avoid scraping cable insulation and generating tiny plastic debris.
Workshop operation and maintenance protection rules strictly limit contamination sources. Silicone-based mold release agents are prohibited entirely; only alcohol-based non-silicone release coatings are allowed to prevent silicone film contamination on thermocouple sensing heads. Before disassembling thermocouples for cleaning, technicians wear dust-free latex gloves and non-shedding cleanroom cloths to avoid hand oil and skin dander adhering to probe surfaces. Weekly cleaning uses lint-free dust-free cloth and medical-grade anhydrous alcohol to wipe sensing heads and cable surfaces, with high-purity dry nitrogen blowing to clear micro dust in manifold deep measuring holes. Spare medical thermocouples are stored in independent sealed dust-free boxes with desiccant, separated from ordinary industrial sensors to avoid cross-contamination.
Regular third-party protection performance inspection is required every six months, testing metal ion precipitation, particle shedding and corrosion resistance of thermocouple assemblies. Any probe with scratched sheath surface or broken seamless sealing must be replaced immediately instead of temporary repair. Complete multi-layer protection measures for cleanroom medical thermocouples eliminate product contamination risks, ensure all molded medical components pass biocompatibility and hygiene audits, and maintain long-term production qualification of medical mold manufacturers.
