As the "nerve endings" of temperature control in the hot runner system, the stability of the temperature sensing wire directly affects the precision and continuity of the injection molding process. Preventing damage to the temperature sensing wires hinges on standardized installation, regular maintenance, environmental protection, and scientific management. Systematic protective measures can significantly extend service life and reduce downtime due to sudden malfunctions.
I. Preventive Measures During Installation
Correct Insertion Direction and Depth
The temperature probe must be inserted facing the melt flow direction to ensure rapid response to temperature changes.
The insertion depth should allow the probe tip to extend 5-10mm beyond the runner centerline to avoid contact with metal surfaces, which could cause temperature measurement lag.
Avoid Mechanical Stress
The bending radius must not be less than [percentage missing] of the wire diameter. 6 times the normal value; sharp-angle bending or forced pulling is prohibited.
Wiring paths should avoid moving parts of the mold and ejector pin areas to prevent squeezing or friction.
Reliable fixing and sealing:
Use original factory clamps or high-temperature resistant pressure blocks for fixing, ensuring a tight fit between the probe and the mounting hole.
Use heat shrink tubing and insulating tape for double wrapping at the joints to prevent oil and moisture intrusion.
Single-point grounding of the shielding layer:
The shielding wire is grounded only at a single point on the controller end to avoid multi-point grounding and ground loop interference.
Signal lines and power lines should be routed in separate cable trays, with a recommended spacing of ≥20cm.
II. Operation and Maintenance Prevention Strategies
Regular electrical testing:
Measure the resistance every 3 months using a multimeter (it should be 109.6Ω±1Ω at 25℃).
Test the insulation resistance to ground every 6 months using a megohmmeter; the normal value should be ≥ 500MΩ
Cleaning and Protection
When shutting down, clean the surface of the temperature sensing wire to remove oil and carbon deposits. Wipe with a dry, soft cloth.
Do not use a high-pressure water gun to rinse, as water may seep into the connector and cause a short circuit.
Temperature Monitoring and Early Warning
Set a temperature fluctuation alarm threshold (e.g., ±3℃) to promptly detect abnormal trends.
Record historical temperature curves and analyze for slow response or drift phenomena.
Preventive Replacement Mechanism
The recommended replacement cycle is generally 3–5 years. For temperature sensing wires operating in high temperature, high humidity, or vibration environments, this should be shortened to 2–3 years.
If multiple wires in the same batch are damaged, it is recommended to perform batch testing on the remaining undamaged wires.
III. Environment and Operating Procedures
Table: Risk Factors, Preventive Measures
High Temperature Aging: Avoid direct contact between the temperature sensing wire and the heating coil; maintain a safe distance.
Humid Environment: Ensure the junction box is properly sealed and moisture-proof; add a desiccant if necessary.
Electromagnetic Interference: Use shielded twisted-pair cable; keep away from frequency converters and high-current cables.
Human Errors Establish Standard Operating Procedures (SOPs); new employees must be trained before starting work.
IV. Management Optimization Suggestions
Establish Inspection Records: Record the time, resistance, insulation value, and operator for each inspection for easy traceability.
Label Management: Attach labels to the temperature sensing wire connectors, indicating the installation date, model, and channel number.
Tool Standardization: Equip with dedicated calibrators and infrared thermometers to improve inspection accuracy.
Training and Assessment: Regularly organize training for maintenance personnel on fault diagnosis and replacement skills.
Best Practices: Integrate "Installation → Inspection → Early Warning → Replacement" into a closed-loop management system to shift from reactive maintenance to proactive prevention, ensuring continuous and stable production.
