High-viscosity engineering plastics such as PC, PMMA and PSU have high melting point, poor fluidity and strict requirements on temperature stability, which put forward higher comprehensive requirements for matching thermocouples.
First, choose ultra-low drift high-precision models. Such plastics require long-term constant temperature stay, and thermocouples must keep error within ±0.5℃ for a long time to avoid viscosity change caused by subtle temperature deviation affecting filling effect.
Second, adopt fast-response thickened probe structure. High-viscosity melt is sensitive to instantaneous temperature change, and fast-sensing thermocouples can timely complete temperature fine adjustment to ensure stable melt fluidity. Thickened probes can resist long-term static high-temperature erosion.
Third, prioritize high-temperature anti-oxidation alloy materials. The molding temperature of such materials is mostly above 300℃, which needs thermocouples with strong high-temperature stability to prevent core wire aging and performance attenuation under ultra-high temperature.
Fourth, select fully sealed anti-pollution structure. High-viscosity plastics are easy to decompose and produce sticky carbon deposits, and fully sealed probes are not easy to be adhered by dirt, keeping long-term accurate temperature measurement and reducing frequent cleaning work.
In layout, install thermocouples close to the front end of flow passages to grasp the real melt temperature in real time, provide accurate data support for process parameter adjustment, and effectively eliminate molding defects such as material flow marks and insufficient filling.
