Maintenance personnel often encounter localized redness on the outer surface of electric heating coils and large fluctuations in barrel temperature. This is usually not a problem with the temperature controller, but rather uneven distribution of the internal resistance wire or improper installation clearance. First cut off the power, use an infrared thermometer to scan the coil surface. If the temperature difference exceeds 15°C, it needs to be removed for inspection.
The DJR-680 electric heating coil has a rated voltage of 220V or 380V, which must be specified when ordering. If a 220V coil is mistakenly connected to 380V on site, the resistance wire will quickly burn out. The working voltage must not exceed 10% of the rated value; for a 380V system, it should be controlled within 418V. Wiring terminals should use high-temperature resistant wires, crimped securely to avoid loose connections and arcing.
This heating coil adopts an annular structure, with the inner wall being stainless steel or a ceramic insulation layer. The resistance wire is wound and then sintered at high temperature. It is covered with a metal protective shell and can be equipped with a K-type thermocouple. It is suitable for barrel heating of injection molding machines, extruders, and blow molding machines, and can also be used for pelletizer die heads. During installation, it is necessary to ensure that the inner wall of the coil fits closely with the outer wall of the barrel. Excessive clearance will lead to reduced heat conduction efficiency.
Excessively high power density will shorten the service life of the resistance wire. Under normal operating conditions, the recommended power density for the DJR-680 should not exceed 4W/cm². If the barrel has poor heat dissipation or frequent cold starts, a low power density model should be selected. When the surface temperature exceeds 400°C for an extended period, the temperature resistance grade of the insulation material must be confirmed.
Before removing the heating coil, the power must be cut off and the coil allowed to cool. When installing a new coil, avoid striking or bending with force to prevent breakage of the internal resistance wire. Regularly check whether the terminals are oxidized and whether the fastening screws are loose. If deformation of the coil body is found or the insulation resistance is below 5MΩ, it should be replaced.
