What Are the Key Differences Between Type J and Type K Thermocouples in Hot Runners?

Type J and Type K are the two most commonly used thermocouple types in the hot runner industry, and each has obvious advantages in application scenarios, temperature range, stability, and versatility. Type K thermocouple has a wide applicable temperature range, good oxidation resistance, small long-term drift, and strong versatility. It is suitable for almost all plastic materials, including engineering plastics with high processing temperatures such as PC, PA, PBT, and PPS. It has good mechanical properties and can be made into various structures such as spring-loaded, armored, threaded, and miniature. It is the most widely used type in the global hot runner industry. Type J thermocouple has higher accuracy and better stability in the medium and low temperature range, with faster response speed, but its temperature range is narrow and oxidation resistance is weak. It is more suitable for general plastics such as PP, PE, PS, and ABS, and precision molds with high requirements for medium and low temperature control. In terms of price and maturity, both are similar, but Type K has higher comprehensive adaptability. In terms of brand matching, most hot runner brands take Type K as the default standard, such as Mold-Masters, Husky, Synventive, YUDO, HASCO, INCOE, and DME. Type J is usually used in specific precision systems. Choosing the wrong type will lead to poor stability, easy drift, short service life, and unstable molding. For users, understanding the differences can help make more reasonable choices. In most cases, Type K is the more stable and universal choice, while Type J is suitable for specific medium and low-temperature precision scenarios.