How To Match Thermocouple Wire Length With Hot Runner Mold Structure

When configuring and maintaining hot runners, a crucial feature that is frequently overlooked is the reasonable matching of thermocouple lead length. Too long lead will be twisted and squeezed in the mould wiring groove, easily worn, burnt at high temperatures, and interfere with mould closing; too short lead will be pushed firmly during mould opening and closing, causing internal wire breakage and terminal coming off. The service life of thermocouples can be successfully extended and mechanical damage can be prevented by carefully choosing the lead length based on mould size, runner layout, and wire path.

The wire path is short and the mould opening stroke is minimal for tiny single-cavity hot runner moulds. Standard short leads can be set up to prevent unnecessary wire wrapping and mould gap occupancy. In order to ensure that the lead is smoothly folded without extrusion when the mould is closed and naturally stretched without tension when the mould is fully opened, medium-sized multi-cavity moulds with middle layout manifolds must reserve enough margin based on the maximum mould opening distance.

massive automobile moulds and stacked hot runner moulds include intricate multi-layer wiring pathways and massive mould opening strokes. To compensate for the displacement caused by mould movement, reserved bending loops are placed at the corner of the wire groove and the thermocouple lead must be extended in segments. Lead cannot be arranged in a straight tension state because the long-term tensile stress will result in insulation layer cracking and internal alloy wire fatigue fracture.

The arrangement of the temperature control cabinet's distance should also be taken into account. Excessively short leads cannot reach the terminal row if the mould is distant from the electrical cabinet, and forced docking will result in poor contact and signal attenuation. When combined with external electromagnetic interference, too lengthy leads might increase the sensing signal transmission distance and cause temperature hopping. In order to ensure that the lead length is precisely matched with the mould structure, wiring path, and cabinet layout, professional hot runner manufacturers will reserve standard length specifications based on mould tonnage and structural type and customise non-standard length for special moulds. This eliminates hidden dangers from the source.