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Chengdu Hot Runner Analyzes the Reasons for Leakage of Hot Runners for Customers of Plastic Mold Hot Runners
Chengdu Hot Runner Analyzes the Causes of Hot Runner Leaks for Plastic Molding Customers
Text by Thermal Hot Runner
Hot runner system leaks have always been a headache for most injection molders, and whenever people talk about hot runners, they worry about potential leaks. How can hot runner suppliers prevent such issues? Today, we’d like to discuss the reasons behind hot runner leaks with Mr. Zhu Guodong, a senior engineer at Chengdu Hot Runner Thermal Constant Flow Runner. With over a decade of experience in the hot runner industry, Mr. Zhu has been dedicated to resolving problems for tens of thousands of hot runners during after-sales services, accumulating extensive practical experience in troubleshooting hot runner issues.
Hot runner systems may leak due to various reasons, and while these leaks might not always seem serious, they can still impact the customer's delivery schedules. In severe cases, they could even damage the heat rings or compromise the entire system. To address this issue, hot runner suppliers must first identify the root cause of the leak and then develop an appropriate maintenance plan. Let’s explore some common reasons for hot runner leaks:
1. The support pads are too low. Under the influence of injection pressure, the runner plate and the hot nozzles separate, creating gaps that lead to leaks.
2. The support pads are too high. The support blocks enter the front mold baseplate, preventing glue from leaking between the flow plate and the hot nozzles. However, under injection and clamping pressures, the flow channel plate is pushed aside, causing leaks.
3. The center pads are too high. The runner plate is unsupported on the center pad, leading to separation from the hot nozzles and subsequent leaks.
4. The center pads are too low. Under the injection pressure of the molding machine, the center pads collapse, resulting in leaks.
5. Uneven nozzle heights. Lower hot nozzles are prone to leaks.
6. The distance between the fixing screws and the flow plates or nozzles is too large. This leads to insufficient sealing between the runner plate and the hot nozzles, causing leaks.
7. Positioning pins are too high. The flow channel plate sits unevenly on the positioning pins, separating from the hot nozzles and creating gaps that result in leaks.
8. The hot nozzles are too long. Without enough room for expansion, pressure builds up, compromising the sealing rings on the hot nozzles and causing leaks.
9. Seals are either too high or too low. A proper pre-compression of about 0.3 mm is needed on the hot nozzle surface. If the seals are too high, the flow channel plate can deform easily, leading to leaks. If they’re too low, there’s no initial compression force, and the system leaks upon heating.
10. Incorrect nozzle positioning. If the hot nozzle head is positioned on the front mold or the front mold insert instead of the actual mold, the injection pressure or clamping pressure can misdirect forces onto the front mold core, causing leaks.
By addressing these specific issues, hot runner suppliers can significantly reduce the occurrence of leaks and ensure smoother operations for their customers. This attention to detail is crucial for maintaining trust and reliability in the plastic molding industry.