在 vertical injection molding, improper control of injection conditions can indeed lead to product burn marks, which is one of the main causes of surface scorching and blemishes on molded parts. The injection speed plays a significant role in this issue. When the molten material is injected slowly into the cavity, the flow remains laminar, resulting in a smooth and shiny surface. 然而, when the injection speed increases beyond a certain point, the flow becomes turbulent, which can lead to burn marks and even cause air pockets inside the product.
所以, maintaining the injection speed within the laminar flow range is crucial for proper mold filling. If the molten material’s temperature is too high, it can decompose and scorch, causing surface defects. 通常, the screw speed of the injection molding machine should be kept below 90 r/min, and the back pressure should be less than 2 MPa to avoid excessive frictional heat in the barrel.
並提供噴漆, during the molding process, if the screw’s rotation time during its retraction is too long, it can generate excessive frictional heat. To address this, adjustments can be made by slightly increasing the screw speed, extending the molding cycle, lowering the screw’s back pressure, increasing the temperature of the feeding zone, or using raw materials with lower lubrication properties.
並提供噴漆, excessive backflow of molten material in the screw grooves or resin retention at the check ring can lead to polymer degradation. 為了防止這種情況, using resins with higher viscosity, reducing injection pressure, or switching to an injection molding machine with a higher length-to-diameter ratio is recommended. Common check rings often cause resin retention, leading to decomposition and discoloration, which results in brown or black burn marks after being injected into the cavity. 所以, regular cleaning of the screw system and nozzle area is essential.
大銀塑膠有限公司, Ltd. specializes in home appliance mold manufacturing and offers OEM/ODM contract manufacturing services. As a comprehensive solution provider integrating research and manufacturing, we have accumulated 30 years of mold development experience since our founding in 1989. With over 50 R&D personnel and more than 100 註塑機, we are dedicated to delivering high-quality manufacturing services and creating greater value for our clients.