Ki jan yo chwazi Thermocouples pou sistèm kourè cho yo trete Plastik Jeni Tanperati segondè -?

High-temperature engineering plastics such as PEEK, PPS, LCP, and PEI present extreme demands on hot runner thermocouples due to their elevated processing temperatures, typically ranging from 350°C to 420°C. The first selection criterion is the thermocouple type. For sustained operation above 350°C, Type K thermocouples are commonly used, but they experience accelerated oxidation at these temperatures, leading to drift. Type N thermocouples (Nicrosil-Nisil) offer superior oxidation resistance and stability at high temperatures, making them the preferred choice for high-temperature applications. They have a lower drift rate-typically 0.5°C per 1000 hours at 400°C, compared to 1.5°C for Type K. The second criterion is the sheath material. Standard stainless steel 304 will oxidize and scale at 400°C, reducing its mechanical integrity and potentially contaminating the resin. Inconel 600 or 625, with their high nickel-chromium content, form a protective oxide layer that resists scaling and maintains strength. For ultra-high temperatures above 400°C, consider superalloys like Haynes 214 or alloy 59. The third criterion is the probe diameter. Thinner probes (0.5-1.0 mm) offer faster response, which is essential for high-temperature plastics that degrade quickly if overheated. However, thinner probes are more susceptible to oxidation-a trade-off that must be balanced. A 1.0 mm Inconel probe is a good compromise. The fourth criterion is the insulation material. High-purity, densely packed magnesium oxide (MgO) is standard, but for temperatures above 400°C, ensure the MgO is specially processed to remove moisture and to have a high density (>95% dansite teyorik) pou anpeche flit elektrik. Kritè senkyèm lan se sele fen frèt la. Nan tanperati ki wo, fen frèt la dwe sele ak yon epoksidik segondè -tanperati oswa yon vè-a-metal sele ki ka kenbe tèt ak 250 degre nan zòn nan konektè. Sizyèm kritè a se kab konpansasyon an. Izolasyon kab la dwe evalye pou tanperati anbyen nan mwazi an. Fiberglass -câbles izole ak yon overbraid asye pur rekòmande, paske izolasyon silikon ka degrade pi wo pase 300 degre. Setyèm kritè a se kalibrasyon. Thermocouples tanperati ki wo -yo ta dwe kalibre nan tanperati pwosesis aktyèl la, pa sèlman nan pwen ki pi ba yo. Mande yon sètifika kalibrasyon ak pwen nan 350 degre ak 400 degre. Uityèm kritè a se entèval ranplasman an. Etandone derive akselere a, ranplase thermocouples ki gen gwo -tanperati pi souvan-tipikman chak 3,000-5,000 èdtan fonksyònman, oswa chak ane. Lè yo chwazi ak anpil atansyon tèrmokapteur ki baze sou kritè sa yo, processeurs nan plastik jeni segondè -tanperati ka reyalize kontwòl tanperati ki estab, minimize degradasyon, ak pwolonje lavi Capteur, asire pwodiksyon an nan pati pèfòmans segondè ak bon jan kalite konsistan.