Causes of Water Leakage in Injection Molds and Mold Jetting

Causes of Water Leakage in Injection Molds

During use, injection molds often experience water leakage problems. The main causes include the following:

Mold design or manufacturing defects: Improper water channel design, insufficient machining accuracy, or aging sealing rings may all lead to water leakage. In particular, when components such as ejector pins, sleeves, or lifter holes are improperly dimensioned, they can easily damage the water channels.

Sealing ring issues: Sealing rings are prone to aging, deformation, or cracking under long-term high-temperature and high-pressure working conditions, which causes them to lose their sealing function. In addition, if the selected sealing ring is not heat-resistant, it may fail in high-temperature environments.

Water channel problems: Residues or blockages inside the water channels may also cause leakage. This is especially common when channels are interconnected or when there are gaps at the bottom of plugged copper holes.

Preventive and corrective measures: Regularly inspect mold water channels and sealing rings, clean water channel residues in time, and replace aged or damaged components.

The Role of the Injection Molding Machine in Mold Water Leakage

Equipment issues: Problems within the injection molding machine itself may also lead to mold water leakage. For example, poor lubrication, excessively high oil temperature, or aging of certain components may result in leakage risks.

Operational issues: Improper operation of the injection molding machine can also be a cause. For instance, insufficient heating, poor cooling water circulation, or excessively fast injection speed may reduce the bonding strength between the machine and mold, thereby causing water leakage.

How to Prevent Mold Water Leakage?

Optimize mold structure to ensure flat mold surfaces, tight contact with the machine, and proper gate design.

Select high-quality mold materials and maintain the mold in good condition.

Strengthen operator training to ensure standardized injection molding operations.

Perform regular maintenance and servicing of injection molding machines to keep equipment in proper working condition.

Continuously monitor the operating status of the injection molding machine during production, and promptly address any water leakage issues once detected.

Characteristics of Mold Jetting (Flow Marks)

Mold jetting, also known as jetting marks or jet flow lines, is one of the common defects in injection molding. It mainly appears as snake-like flow lines near the gate, severely affecting the appearance of the product. The characteristics are as follows:

• Thread-like flow lines: Jetting appears as fine, elongated lines on the product surface, usually curved and continuous, resembling snake-like patterns.
• Specific location: Jetting typically occurs near the gate, especially in molds with side gates. This happens because the melt passes through a narrow gate at high speed and suddenly enters a wider area, leading to unstable melt flow.
• Difficult to fuse: Since the jetted melt rapidly cools upon contacting the mold surface, it cannot fully fuse with the subsequent melt entering the cavity, resulting in visible jetting marks.
• Solutions: Improvements can be made in processing conditions, raw material handling, and mold design. For example, lowering nozzle and melt temperature, reducing nozzle orifice diameter, pre-drying materials, and applying optimized mold designs.

Understanding the causes and characteristics of injection mold water leakage and mold jetting is crucial for improving product quality. By adopting appropriate preventive and corrective measures, manufacturers can effectively reduce the occurrence of these problems, thereby enhancing overall product quality and production efficiency.