According to installation space and mold internal wiring layout, hot runner thermocouples are divided into straight type and bent type two mainstream structural forms. They are consistent in temperature measuring principle, core material and temperature resistance grade, but differ greatly in installation angle, space occupation, application position and later maintenance convenience.
Straight thermocouple is the most universal standard model, with linear integrated structure, simple processing and low manufacturing cost. It is suitable for vertical and horizontal straight line installation positions with sufficient internal space of molds, such as mainstream manifold main temperature measuring points and open nozzle vertical temperature measuring holes. It features smooth probe penetration, close fitting, fast heat conduction and stable temperature collection, and is convenient for disassembly, calibration and daily replacement.
Bent thermocouple is designed with right-angle or special-angle bending structure, specially developed for narrow installation space, blocked straight line channels and side hidden temperature measuring positions inside complex molds. It can bypass internal sliding blocks, thimble mechanisms and reinforced structural parts of molds to complete temperature monitoring work that straight sensors cannot realize. It is widely used in deep cavity molds, inclined top molds and compact multi-cavity dense arrangement molds.
In use performance, straight thermocouples have stronger overall structural rigidity, better anti-vibration performance and longer service life under long-term frequent mold opening vibration. Bent thermocouples have stress concentration at the bending position, and repeated vibration and thermal expansion are easy to cause internal core wire fatigue fracture after long-term use, so the failure rate is slightly higher than straight models.
In wiring arrangement, bent thermocouples can realize hidden steering wiring inside molds, make internal harness layout neater, effectively avoid wire extrusion friction, and reduce external exposed wiring length. In actual selection, choose straight thermocouples preferentially for conventional standard molds to control cost and stabilize performance; select customized bent thermocouples for special structure molds with limited space to meet installation layout demands. It is forbidden to bend straight thermocouples artificially for forced installation, which will directly damage internal sensing structure and cause permanent failure.
