What Is Difference Between Straight and Bent Hot Runner Thermocouples

Hot runner thermocouples are classified into two common structural types: straight type and bent type, depending on the installation area and mold internal wire configuration. They differ significantly in terms of installation angle, space occupation, application position, and ease of maintenance afterward, but they are similar in terms of temperature measuring principle, core material, and temperature resistance grade.

The most widely used standard model is the straight thermocouple, which has a linear integrated structure, easy processing, and inexpensive production. It is appropriate for both horizontal and vertical straight line installation locations with enough internal mold space, such as open nozzle vertical temperature measuring holes and mainstream manifold main temperature measuring points. It is easy to disassemble, calibrate, and replace on a daily basis. It has smooth probe penetration, close fitting, quick heat conduction, and stable temperature collecting.

Bent thermocouples are specifically made for small installation spaces, obstructed straight line channels, and side-hidden temperature measurement locations inside intricate molds. They have a right-angle or special-angle bending structure. It can accomplish temperature monitoring tasks that straight sensors cannot by avoiding internal sliding blocks, thimble mechanisms, and reinforced structural elements of molds. It is frequently utilized in compact multi-cavity dense arrangement molds, inclined top molds, and deep cavity molds.

When it comes to long-term, frequent mold opening vibration, straight thermocouples perform better in terms of overall structural rigidity, anti-vibration performance, and service life. The failure rate of bent thermocouples is marginally greater than that of straight models because of the stress concentration at the bending position and the ease with which internal core wire fatigue fracture can be caused by repeated vibration and thermal expansion after extended operation.

Bent thermocouples can be used in wiring arrangements to provide hidden steering wiring inside molds, improve the internal harness architecture, successfully prevent wire extrusion friction, and shorten the length of exterior exposed wiring. For ordinary standard molds, pick straight thermocouples to control costs and stable performance; for specific structure molds with limited space, consider bespoke bent thermocouples to suit installation layout requirements. Straight thermocouples cannot be artificially bent for forced placement since this would directly harm the internal sensing mechanism and result in permanent failure.