Yuav Ua Li Cas Xaiv Cov Thermocouples rau Cov Cuab Yeej Kub Ua Haujlwm Ua Haujlwm Siab -Tsuas Kub Engineering Plastics?

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% theoretical ntom) los tiv thaiv hluav taws xob. Qhov thib tsib txheej txheem yog qhov txias kawg sealing. Thaum qhov kub thiab txias, qhov kawg txias yuav tsum tau ntim nrog lub siab - kub epoxy los yog iav - mus rau - hlau foob uas tuaj yeem tiv taus 250℃ntawm thaj chaw txuas. Qhov thib rau kev ntsuas yog cov nyiaj them poob haujlwm. Lub rwb thaiv tsev cable yuav tsum tau ntsuas rau qhov ntsuas kub ntawm qhov pwm. Fiberglass- insulated cables nrog stainless hlau overbraid yog pom zoo, raws li silicone rwb thaiv tsev yuav degrade tshaj 300 degree. Lub xya txheej txheem yog calibration. Siab-kub thermocouples yuav tsum tau ntsuas ntawm qhov ua tau zoo, tsis yog ntawm cov ntsiab lus qis xwb. Thov daim ntawv pov thawj calibration nrog cov ntsiab lus ntawm 350℃thiab 400℃. Qhov thib yim txheej txheem yog lub sijhawm hloov pauv. Muab qhov nrawm nrawm, hloov siab -kub thermocouples ntau zaus-feem ntau txhua txhua 3,000-5,000 teev ua haujlwm, lossis txhua xyoo. Los ntawm kev ua tib zoo xaiv cov thermocouples raws li cov qauv no, cov txheej txheem ntawm high -kub engineering plastics tuaj yeem ua tiav qhov ntsuas kub ruaj khov, txo qis degradation, thiab txuas ntxiv lub neej sensor, ua kom cov khoom ua tau zoo nrog cov khoom zoo ib yam.