Replacing hot runner temperature sensing cables is a crucial operation for ensuring stable injection molding temperatures. It requires combining equipment power-off, precise disassembly and assembly, and subsequent calibration. The core steps include: power-off and cable removal → removing the old temperature sensing cable → installing the new temperature sensing cable → resetting the wiring → verifying resistance and temperature control. The detailed operating procedure is as follows:
I. Preparation Before Operation
Safe Power-Off Turn off the hot runner controller and main power supply to prevent electric shock or short circuit risks from live work.
Tool Preparation Prepare a digital multimeter, an Allen wrench, insulating tape, a heat gun (if heating is required for disassembly), and labels (for marking the wiring).
Model Compatibility Confirmation The new temperature sensing cable should be the same model as the original, commonly a PT100 three-wire platinum resistance thermometer. Ensure the resistance characteristics (100Ω at 0℃) and connector specifications are compatible.
II. Removing the Old Temperature Sensing Cables
Marking the Wiring Before disconnecting the cables, use labels to mark the corresponding channel for each signal wire to avoid incorrect connections. Disconnection: Disconnect the temperature sensing wire from the control box terminals or junction box, taking care to protect the terminals from damage.
Remove Fixing Structure: Loosen the fixing clamps, pressure blocks, or screws on the temperature sensing wire in the mold or nozzle, and slowly pull out the old wire, avoiding pulling on surrounding wiring.
III. Installing the New Temperature Sensing Wire
Check the Condition of the New Wire: Use a multimeter to measure the resistance of the new temperature sensing wire. At room temperature (25℃), it should be approximately 109.6Ω. Confirm there are no open circuits or short circuits.
Wiring Guidelines
Run the wire along the original path, avoiding contact with heating coils and moving parts.
Bending radius should be no less than 6 times the wire diameter to prevent internal wire breakage.
Use cable ties or special clamps for securing; spacing should be ≤30cm.
Connection Treatment
For soldered connections, use low-temperature solder. After soldering, double-wrap with insulating tape and waterproof adhesive.
For plug-in connections, ensure the plug is securely locked and makes reliable contact.
IV. Wiring and System Restoration
Connect according to markings
Connect the new temperature sensing wire to the corresponding original channel, ensuring the compensating wire is correctly positioned in the three-wire connection method.
Restore Power
Restart the controller and observe for alarms such as "E1" or "Sensor Open". If no abnormalities occur, proceed to the next step.
V. Function Verification
Resistance Retest
Measure the resistance again at the control terminal to confirm that the resistance value is normal and stable after installation.
Temperature Calibration: Start the heating program and observe whether the temperature rise is smooth.
Use an infrared thermometer to compare the actual temperature on the nozzle surface with the value displayed on the controller; the deviation should be ≤ ±3℃.
Trial Production: Conduct trial production and monitor temperature fluctuations in this area to ensure that the control accuracy meets process requirements.
Precautions:
Avoid covering the temperature sensing wire with heavy objects or performing secondary processing such as drilling.
Do not use high-pressure water to clean; wipe with a dry, soft cloth.
For long-term shutdown, disconnect the power and allow it to cool before storing.
