{"id":1513,"date":"2025-05-27T03:07:58","date_gmt":"2025-05-27T03:07:58","guid":{"rendered":"https:\/\/yuanfang.com\/?p=1513"},"modified":"2025-06-18T04:05:41","modified_gmt":"2025-06-18T04:05:41","slug":"hold-pressure-in-plastic-injection-molding","status":"publish","type":"post","link":"http:\/\/yuanfang.com\/it\/hold-pressure-in-plastic-injection-molding\/","title":{"rendered":"Hold Pressure in Plastic Injection Molding"},"content":{"rendered":"

Hold Pressure in Plastic Injection Molding<\/h1>\n\n\n\n

I. The Core Function and Impact of Hold Pressure<\/strong><\/h2>\n\n\n\n

1.1 Primary Objectives of Hold Pressure<\/strong><\/h3>\n\n\n\n

The hold pressure is set to prevent resin backflow and compensate for shrinkage during cooling, ensuring optimal molding results. If set too high, it may cause flash, overfilling, or stress concentration near the gate. Conversely, insufficient hold pressure leads to excessive shrinkage and dimensional instability. The initial injection pressure facilitates mold filling, while hold pressure is critical for maintaining part quality and minimizing shrinkage.<\/p>\n\n\n\n

1.2 Relationship with Back Pressure and Process Parameters<\/strong><\/h3>\n\n\n\n

Back pressure ensures consistent resin mixing, part quality, and control over the injection screw\u2019s movement. Hold pressure works in tandem with the pressure switchover point and holding time. Inadequate hold pressure results in dents, bubbles, increased shrinkage, dimensional deviations, and inner-layer orientation from melt backflow. Excessive pressure causes sprue stress, difficult mold release, and outer-layer tensile stress.<\/p>\n\n\n\n

II. Key Factors in Hold Pressure Optimization<\/strong><\/h2>\n\n\n\n

2.1 Multistage Hold Pressure Strategies<\/strong><\/h3>\n\n\n\n

Gradually decreasing hold pressure (multistage control) can:<\/p>\n\n\n\n