Common defects in motor injection molding and their preventive measures

In the motor manufacturing process, injection molding technology plays a vital role. It not only determines the shape and structure of the motor housing and parts, but also directly affects the quality and performance of the final product. However, in the injection molding process, defects such as bubbles, shrinkage marks, and deformation often trouble producers. These defects not only affect the appearance of the product, but may also weaken its structural strength, reduce its service life, and even cause functional failure. Therefore, mastering effective preventive measures is crucial to improving the quality of motor injection molding.

1. Bubble formation and avoidance strategy
Bubbles are one of the most intuitive and difficult to avoid defects in injection molding. Its existence not only destroys the aesthetics of the product, but also may become a stress concentration point and reduce the overall strength of the product.

Raw material drying: Moisture and volatiles in the raw materials are one of the main reasons for bubble formation. Therefore, before injection molding, the raw materials must be fully dried. This usually involves using a hot air dryer or a dehumidifying dryer to set the appropriate temperature and time according to the characteristics of the raw materials to ensure that moisture and volatiles are completely removed.

Injection molding process adjustment: The optimization of process parameters is also critical. Excessive screw temperature and feed port temperature can cause the melt to overheat and decompose, generating gas. Therefore, appropriately lowering these temperatures can effectively reduce the generation of bubbles. At the same time, increasing the back pressure of the storage material helps to compact the melt and reduce the mixing of air and residual glue; while reducing the screw ejection position can prevent the melt from inhaling air due to excessive retreat before injection.

Mold exhaust: Mold design also needs to consider exhaust performance. Reasonable exhaust groove design can ensure that the gas can be discharged smoothly when the melt fills the mold, avoiding being trapped inside the finished product to form bubbles. Regular inspection and maintenance of the mold exhaust system to ensure that it is unobstructed is an important measure to prevent bubbles.

2. Prevention of shrinkage marks
Shrinkage marks are depressions formed by the volume shrinkage of the melt during the cooling and solidification process, and the failure of the mold surface to obtain sufficient melt replenishment. It not only affects the appearance, but may also affect the assembly accuracy and sealing of the product.

Adjust injection pressure and speed: Increasing injection pressure and speed can speed up the flow rate of the melt, allowing the melt to better fill the mold and reduce the occurrence of shrinkage marks. However, it should be noted that excessive pressure and speed may cause overflow or mold damage, so it is necessary to adjust according to the actual situation.

Optimize mold temperature: Appropriately increasing the mold temperature can extend the cooling time of the molten material, giving the molten material more time to flow and replenish, thereby reducing shrinkage marks. At the same time, ensure that the temperature of each part of the mold is uniform to avoid shrinkage marks caused by excessive local cooling.

3. Control of deformation
Deformation is mainly caused by excessive temperature difference between the inside and outside of the injection molded part during the cooling process, or stress concentration caused by unreasonable mold design.

Uniform cooling: Optimizing the design of the cooling system to ensure that the cooling speed of each part of the injection molded part is consistent is the key to reducing deformation. Using a multi-circuit cooling system and reasonably arranging cooling water channels can effectively control the cooling rate and reduce deformation.

Mold design optimization: When designing the mold, the structural characteristics of the product should be considered, the demoulding slope should be reasonably set, and too deep side walls or sharp angles should be avoided to reduce stress concentration and deformation.

In short, defects such as bubbles, shrinkage marks, and deformation in motor injection molding can be effectively prevented and controlled through meticulous raw material processing, precise process adjustment, reasonable mold design, and effective cooling control. Manufacturers should continue to explore and practice, combine the characteristics and needs of specific products, and formulate the most appropriate preventive measures to continuously improve the quality and efficiency of motor injection molding.