To reduce the outer diameter of injection-molded parts, the following methods can be used:
Adjusting Shrinkage Rate: Shrinkage rate refers to the dimensional change of an injection-molded part due to material shrinkage during cooling. Adjusting the shrinkage rate of the injection molding material can effectively control the outer diameter of the part. Specific methods include selecting materials with lower shrinkage rates or reducing shrinkage during injection molding by adjusting process parameters (such as cooling time and mold temperature).
Optimizing the Holding Pressure Process: Holding pressure refers to applying pressure to the molten material after it has filled the mold cavity during injection molding to maintain its fullness and density. Appropriately increasing the holding pressure and holding time can reduce the outer diameter of the injection-molded part. This is because during the holding pressure process, the molten material further fills the mold cavity under pressure, thus reducing the final product size.
Controlling Injection Speed and Temperature: Injection speed and temperature are important factors affecting the size of injection-molded parts. Reducing the injection speed reduces the kinetic energy of the molten material during filling, thereby reducing the expansion effect caused by impacting the mold wall and consequently reducing the outer diameter. Simultaneously, appropriately lowering the melt temperature and mold temperature can also reduce the thermal expansion of the material, helping to control the outer diameter of the injection-molded parts. However, it is important to note that when adjusting these parameters, their impact on the quality of the injection-molded parts and production efficiency should be comprehensively considered.
In summary, by adjusting the shrinkage rate, optimizing the holding pressure process, and controlling the injection speed and temperature, the outer diameter of injection-molded parts can be effectively reduced. In actual operation, adjustments should be made flexibly according to specific product requirements and process conditions.