What is automotive injection molding?

1, Definition of Automotive Injection Molding
Automotive injection molding, in short, is the production process of injecting plastic raw materials into a mold under high temperature and pressure conditions, allowing them to cool and solidify inside the mold, thereby obtaining automotive parts with complex shapes. This technology is widely used in the automotive manufacturing industry, covering almost every corner of the car. From the body shell, headlight lenses, interior parts to engine components, injection molding processes can produce both beautiful and practical parts.
2, The principle of automotive injection molding
The basic principle of automotive injection molding is based on the fluidity and plasticity of plastics. Plastic raw materials are heated to a molten state at high temperatures and have good fluidity. Subsequently, the molten plastic is high-pressure injected into the mold cavity through the injection system of the injection molding machine. The design of the mold determines the shape and size of the injection molded parts. In the mold, molten plastic comes into contact with the mold surface, and heat transfer gradually cools and solidifies the plastic. After the plastic is completely cured, the mold is opened and the injection molded product is removed. After necessary post-processing such as deburring, polishing, spraying, etc., it finally becomes a qualified automotive component.
3, The process flow of automotive injection molding
The process flow of automotive injection molding mainly includes the following steps:
Raw material preparation: Select suitable plastic raw materials according to product requirements, such as polypropylene (PP), polyethylene (PE), polycarbonate (PC), etc., and perform pre-treatment such as drying, mixing, etc.
Plastic melting: Heating the pre treated plastic raw material to a molten state to give it good fluidity. This step is usually carried out in the barrel of the injection molding machine.
Injection molding: Molten plastic is high-pressure injected into the mold cavity under the action of an injection molding machine to form the desired shape. Strict control of injection pressure, speed, and time is required during the injection molding process to ensure the quality and accuracy of the injection molded parts.
Cooling solidification: In the mold, the molten plastic gradually cools and solidifies. The temperature and cooling system of the mold have a significant impact on the dimensional accuracy and internal stress of injection molded parts.
Mold opening and component retrieval: After the plastic is completely cured, the mold is opened and the injection molded product is retrieved.
Post processing: Necessary post-processing of injection molded products, such as deburring, polishing, spraying, etc., to improve their appearance quality and performance.
4, Key parameters of automotive injection molding
In the process of automotive injection molding, process parameters such as injection temperature, pressure, and speed play a crucial role, directly affecting the dimensional accuracy, internal stress, and mechanical properties of the injection molded parts.
Injection molding temperature: Injection molding temperature mainly affects the dimensional accuracy of automotive injection molded parts by affecting the flowability and shrinkage rate of plastic melt. The appropriate injection molding temperature can fully stretch the plastic molecular chains, which is beneficial for improving the tensile strength and impact toughness of injection molded parts. However, excessively high or low temperatures can lead to a decrease in the quality of injection molded parts, such as dimensional deviations and increased internal stress.
Injection pressure: Injection pressure directly affects the filling of the melt in the mold cavity and the compaction degree of the plastic. A higher injection pressure can ensure that the melt completely fills the mold cavity, but excessive injection pressure can cause elastic deformation of the mold cavity, resulting in dimensional deviations of the injection molded parts. Meanwhile, injection pressure is also one of the important factors that generate internal stress.
Injection speed: The injection speed determines the speed at which the melt enters the mold cavity. A faster injection molding speed can allow the melt to fill the mold cavity in a short period of time, reducing the heat loss of the melt during the flow process. However, if the injection molding speed is too fast, the melt will form turbulent flow in the mold cavity, which is prone to air entrainment and the generation of bubbles, affecting the dimensional accuracy and surface quality of the injection molded parts.
5, Application of Automotive Injection Molding in the Automotive Industry
The automotive injection molding process is widely used in the manufacturing of automotive components, covering almost every corner of the car. From the body shell, headlight lenses, interior parts to engine components, injection molding technology can produce both beautiful and practical parts. For example, components such as the dashboard, center console, door handles, bumper, and seats not only need to have good mechanical performance, but also meet strict appearance requirements. Injection molding technology, with its unique advantages, has occupied a place in this field. In addition, with the rise of new energy vehicles, injection molded parts also play an important role in the manufacturing of key components such as battery packs and motor casings.