How to Prevent Screw Leakage in Hot Runner
Hot runner is an important tool used in plastic injection molding. A hot runner system usually consists of a heated manifold and hot tips, at the end of which the thermoplastic is injected into the mold cavity. The requirement of the system is very strict so that the plastic parts can get good shapes and sizes.
However, due to improper operation and design, issues such as screw leakage can occur. Screw leakage refers to the plastic resin leaking out of the nozzle around the plastic material screw. This leakage affects not only the quality of the plastic parts, but it also has a negative impact on the performance and life of the injection molding machine.
The following are several tips for preventing screw leakage in the hot runner system:
1. Ensure that the injection molding machine is properly maintained. The injection molding machine needs to be regularly checked and serviced to identify any defects. It is important to repair any minor problems quickly to avoid serious damage to the machine.
2. Ensure that the hot runner system is properly designed. The hot runner system needs to be designed correctly in order to ensure optimal performance. The control temperature of the nozzle should be as close to the optimal plasticating temperature as possible. In addition, the length of the nozzle should be short enough to ensure that the plastic material can reach the mold cavity quickly.
3. Ensure that the screw is designed properly. The screw needs to be designed to be able to work with the hot runner system. The proper design will reduce the temperature difference between the nozzle and the mold cavity, allowing for more consistent plasticating temperatures.
4. Configure the injection pressure according to the plastic material. The plastic material being used needs to be taken into account before configuring the injection pressure. For example, if using rigid plastic materials, a higher injection pressure may be required in order to prevent screw leakage.
5. Ensure that the nozzle is properly maintained. The nozzle should be cleaned regularly to remove any build-up of plastic material on it. In addition, the nozzle should be checked for signs of wear and tear on a regular basis.
6. Monitor the plastic injection speed. The plastic injection speed should be monitored on a regular basis to ensure that it is not too high. High injection speeds can cause material breakdown and cause screw leakage.
7. Utilize proper material flow channels. The material flow channels should be designed properly to ensure that the plastic material flows smoothly through the system. This will reduce the chances of screw leakage.
8. Utilize proper cooling times. Cooling times should be discussed with the plastic injection molder, as this will affect the flow of the plastic material. If the cooling times are too long, the plastic will become too cold, resulting in increased screw leakage.
By following these tips, screw leakage in the hot runner system can be prevented. It is important to ensure that the hot runner system is properly designed and maintained, as this will reduce the likelihood of any sort of screw leakage. Additionally, it is important to properly configure the machine parameters, as this will reduce the risks of screw leakage occurring.
