How do you troubleshoot hot runner system leakage and identify the root cause?

1 Check the nozzle tip

The nozzle tip is the part that connects the hot runner system to the mold cavity. It is exposed to high pressure and temperature, and can wear out or crack over time. If the nozzle tip is loose, damaged, or misaligned, it can allow molten plastic to leak out of the system. To check the nozzle tip, you can inspect it visually, measure its diameter, and test its alignment with the mold gate. You can also use a thermal imaging camera to detect any hot spots or temperature variations that indicate a leak.

2 Inspect the manifold

The manifold is the component that distributes the molten plastic from the injection unit to the nozzle tips. It consists of channels, heaters, thermocouples, and seals. If the manifold is poorly designed, poorly maintained, or poorly installed, it can cause leakage in the hot runner system. To inspect the manifold, you can look for signs of wear, corrosion, deformation, or contamination in the channels and seals. You can also check the electrical connections, the heater resistance, and the thermocouple accuracy. You can also use a pressure sensor to monitor the pressure drop across the manifold.

5 Test the mold

The mold is the tool that shapes the final product. It can contribute to the leakage in the hot runner system by affecting the alignment, the clamping, and the venting of the system. For example, if the mold is misaligned, unclamped, or poorly vented, it can create gaps, distortions, or back pressure in the system. To test the mold, you can measure its dimensions, its flatness, and its parallelism. You can also check its clamping force, its venting channels, and its ejector pins.

6 Analyze the data

The data is the information that you collect from the previous steps. It can help you troubleshoot the leakage in the hot runner system and identify the root cause. To analyze the data, you can use tools such as Pareto charts, fishbone diagrams, or 5 whys. These tools can help you prioritize the most significant factors, find the causal relationships, and determine the corrective actions. You can also use tools such as statistical process control (SPC), failure mode and effects analysis (FMEA), or root cause analysis (RCA). These tools can help you monitor the performance, assess the risks, and verify the results.