During inspections in the injection molding workshop, if large temperature fluctuations or slow heating of the barrel are found, it is often necessary to check whether the electric heating ring is matched or aging. On-site maintenance personnel can first check the surface parameters of the old ring, and then troubleshoot and select according to the following Q&A.
The surface power density is usually 2.53 W/cm². This value is related to the heat dissipation conditions of the heating ring, the barrel material, and the insulation layer. If the power density is too high, the local temperature may exceed the material's tolerance range; if it is too low, the heating time will be prolonged. On site, the appropriate power can be selected based on the barrel diameter and required temperature, referring to this range.
This is a key step in operation and maintenance. The inner diameter of the heating ring must match the outer diameter of the original heating ring or barrel. Excessive clearance will reduce heat conduction efficiency and increase the temperature of the ring itself; interference fit will make assembly difficult. Before installation, the barrel outer diameter should be measured, and it should be confirmed that the inner surface of the ring is free of deformation and debris. After tightening, a feeler gauge can be used to check the clearance to ensure uniform contact.
It is recommended to regularly measure the cold resistance and insulation resistance of the heating ring. For three-phase heating rings, it is also necessary to check whether the current in each phase is balanced. If abnormal surface temperature, decreased insulation resistance, or oxidized wiring terminals are found, they should be dealt with promptly. When replacing, the original model, voltage, power, and dimensions should be recorded to avoid selecting based only on appearance.
