Differences Between Straight and Angled Hot Runner Thermocouples in Practical Use

Straight type and bent angle type are two mainstream appearance structures of hot runner thermocouples. They are different in installation mode, applicable space, temperature measurement effect and service life performance, and users need to select reasonably according to mold internal structure and reserved hole position design.

Straight rod thermocouple is the most traditional and common structure, featuring simple overall shape, convenient processing and low manufacturing cost. It is mainly applicable to hot runner nozzles and manifolds with open installation positions, straight reserved temperature measuring holes and sufficient operating space. During installation, it can be directly inserted along the linear hole position with simple operation and high assembly efficiency. After installation, the stress is uniform without bending torsion, the internal wire core layout is smooth, and it is not easy to produce structural fatigue damage in long-term high-temperature environment, owning longer average service life and more stable comprehensive performance. In daily maintenance, disassembly and cleaning are more convenient, which is the preferred conventional model for most standard hot runner molds.

Bent angle thermocouple is specially developed to solve the problem of limited installation space. Common bending specifications include ninety degrees, one hundred and twenty degrees and oblique bending shapes. Its biggest advantage is strong space obstacle avoidance ability, which can bypass mold reinforcing ribs, cooling water pipes and dense nozzle structures, smoothly reach hidden temperature measuring positions that straight thermocouples cannot enter. It is widely used in side gate, submarine gate and compact multi-cavity dense arrangement molds, which greatly reduces the difficulty of early mold hole position design.

However, bent thermocouples have inherent structural shortcomings. Bending forming will produce permanent structural stress inside the probe and internal wire core. Under long-term high-temperature heating and vibration environment, the bending position is prone to fatigue fracture, and the failure rate is higher than straight products. Meanwhile, the bending section is easy to be squeezed by surrounding mold parts, resulting in probe deformation and poor contact, which affects the accuracy of temperature measurement. In addition, the processing difficulty of bent products is higher, and the market sales price is also relatively higher.

In actual on-site selection, follow the principle of priority straight rod for sufficient space and prefer bent angle for blocked positions. For core temperature measuring points with high stability requirements, try to adopt straight thermocouples to ensure long-term stable operation. For auxiliary measuring points with narrow space and difficult construction, use bent products for matching. Correct selection and collocation can not only meet the installation and layout demands of different molds, but also control the failure rate of accessories, balance use cost and use effect, and create stable conditions for hot runner temperature control work.