Improper twisting and stranding of thermocouple positive and negative wires during wiring arrangement is a common overlooked mistake in mold assembly. Random twisting angle, excessive winding turns and chaotic stranding will interfere with weak thermoelectric potential signals, induce electromagnetic self-induction, and cause irregular temperature fluctuation and signal drift even without external electromagnetic interference.
Thermocouple relies on the potential difference generated by two different alloy wires to transmit temperature signals. Excessive twisting changes the spatial magnetic field distribution of the wire loop, generates tiny induced current, superimposes clutter on normal temperature signals, and makes the controller unable to identify real temperature data. In severe cases, regular cyclic temperature jitter appears, leading to periodic changes in melt viscosity and periodic fluctuation of product weight in batch production.
In standardized wiring specifications, positive and negative wires should be arranged in parallel naturally with moderate loose binding, without excessive winding, random twisting or cross looping. The wiring loop area should be minimized to reduce self-induction interference. Separating thermocouple signal wires from high-current power lines and avoiding parallel winding with heater cables can further enhance signal stability. Regulating wire twisting habits is a simple but effective low-cost measure to eliminate invisible signal interference and maintain hot runner temperature control accuracy.
