1、 Method for testing the insulation of mold heating tubes
Insulation resistance test
The most common method is to use an insulation resistance tester. Before testing, it is necessary to ensure that the heating tube is in a power-off state and the surface is clean and dry, as moisture and dirt may affect the test results. Connect the two test wires of the tester to the wiring terminals of the heating tube and the housing of the heating tube, respectively. For mold heating tubes with lower rated voltages (such as 220V or 380V), their insulation resistance should generally not be less than 1M Ω. If the insulation resistance value is too low, it indicates that there may be a problem with the insulation performance of the heating tube.
For example, in the testing of a heating tube for a small injection mold, when the ambient temperature is 25 ℃ and the humidity is 50%, a 500V insulation resistance tester is used for testing. The normal insulation resistance value of the heating tube reaches 2M Ω, which meets the requirements for safe use.
Voltage withstand test
This is a more rigorous testing method. Using a voltage tester, apply a test voltage to the heating tube that is a certain multiple higher than its rated voltage for a period of time (usually 1-5 minutes). For example, for a heating tube with a rated voltage of 220V, a test voltage of 1000V-1500V may be applied. If the heating tube does not experience breakdown or flashover during the withstand voltage test, it indicates that its insulation performance is good. However, voltage withstand testing has a certain degree of destructiveness and may cause damage to heating tubes that already have potential insulation problems. Therefore, it is generally used for the acceptance of new heating tubes or for testing heating tubes suspected of having serious insulation problems.
2、 Measures to maintain the insulation of mold heating tubes
Prevent moisture
The humidity in the environment where the mold heating tube is located should be controlled as low as possible. If the working environment has high humidity, it may be considered to seal and protect the heating tube, or install dehumidification equipment. For example, in some mold workshops in coastal areas, dehumidifiers are used during the rainy season to control the humidity in the workshop below 60% to reduce the possibility of heating tubes getting damp.
Avoid mechanical damage
During installation and use, it is necessary to prevent the outer shell of the heating tube from being scratched or bumped. Because once the shell is damaged, it may damage its internal insulation structure. For example, when handling molds, attention should be paid to protecting the heating tube to avoid contact with other hard objects.
Regular cleaning
Impurities such as dust and oil on the surface of the heating tube may reduce its insulation performance. It is necessary to regularly clean the surface of the heating tube with a clean cloth or appropriate cleaning agent. However, during the cleaning process, it is important to avoid the entry of cleaning agents into the wiring terminals and other parts of the heating tube to prevent short circuits.
Reasonable use and selection
Ensure that the working voltage, current, and other parameters of the heating tube are within the rated range. If overloaded for a long time, it may accelerate the aging of the insulation material inside the heating tube. At the same time, when selecting, it is necessary to choose heating tube products with reliable quality and good insulation performance. For example, choosing a heating tube with a high-quality magnesium oxide powder insulation layer, which has good insulation performance and thermal conductivity, can effectively improve the insulation and heating effect of the heating tube.
