Analysis of the injection molding process of automotive electric strut bushing injection molding accessories

The key position of injection molding process
The performance requirements of automotive electric Strut Bushing Injection Molding Accessories are extremely stringent. It not only has to withstand various mechanical stresses during vehicle driving, but also has to have good shock absorption and noise reduction effects to ensure driving comfort. The injection molding process gives the accessories precise shape and dimensional accuracy by accurately injecting the molten material into the mold cavity, meeting its complex design requirements. It can be said that without advanced and stable injection molding technology, it is difficult to produce high-quality automotive electric strut bushing injection molding accessories, which in turn affects the overall performance of the vehicle.
Detailed process of injection molding process
Mold design and manufacturing
The mold is the soul of the injection molding process. When designing an injection mold for an automotive electric strut bushing, engineers need to consider many factors comprehensively. The first is the geometry of the bushing, which often has a complex profile to adapt to the installation and functional requirements of the electric strut system. Some bushings may have special slots or protrusions for close fit with other components. Secondly, the dimensional accuracy requirements are extremely high. Any slight deviation may cause problems in the actual use of the bushing, such as improper assembly clearance with the electric support, affecting the support and shock absorption effect. The tolerance requirements also need to be set accurately to ensure the consistency of mass production. Injection molding process parameters, such as injection pressure, temperature, speed, etc., will also have an impact on mold design. When manufacturing the mold, high-quality mold steel materials are selected, and advanced processing technologies such as CNC machining and EDM are used to ensure the high precision and high surface quality of the mold. After the mold is manufactured, strict debugging and inspection are required. The mold trial is used to check whether the opening and closing of the mold is smooth and whether the cavity is filled evenly. Only when all performance indicators meet the requirements can the mold be put into formal production. ​
Raw material preparation​
Different materials have different properties and perform differently during the injection molding process. Taking commonly used rubber materials as an example, natural rubber needs to be plasticized before molding to reduce its molecular weight, improve plasticity, and facilitate subsequent mixing and molding. During mixing, various compounding agents, such as vulcanizers, accelerators, fillers, etc., need to be added to improve the properties of rubber. After mixing, the rubber needs to be preheated to reach a suitable processing temperature and improve fluidity. For polyurethane materials and engineering plastics, the drying process is particularly important. Polyurethane materials are easy to absorb moisture, and moisture will cause hydrolysis of the material during the injection molding process, reducing the performance of the product, so the moisture content must be reduced to the specified range by vacuum drying and other methods. Engineering plastics such as polyamide (PA) need to control the temperature and time during drying to prevent overheating and degradation of the material. Only raw materials that have been fully pretreated can be smoothly molded during the injection molding process to ensure product quality. ​
Injection molding​
Injection molding is the core step of the entire process. After the pretreated raw materials are added to the barrel of the injection molding machine, the barrel gradually heats the material to a molten state through a heating device. The screw of the injection molding machine rotates under the drive of the motor to push the molten material forward. When a certain injection volume is reached, the screw moves forward quickly under the action of the hydraulic system, injecting the molten plastic into the mold cavity at extremely high pressure and speed. The size of the injection pressure directly affects the filling effect of the material in the cavity. Too low pressure may lead to insufficient filling of the cavity and material shortage; too high pressure may cause defects such as flash and deformation of the product. The injection speed is also critical. Too fast speed will prevent the air in the cavity from being discharged in time, forming bubbles; too slow speed will cause uneven flow of the material in the cavity, affecting the appearance and performance of the product. The mold temperature also has an important influence on injection molding. The appropriate mold temperature can promote the flow and solidification of the material and ensure the dimensional accuracy and surface quality of the product. The cooling time determines the degree of solidification of the product in the mold. If the cooling time is insufficient, the product may have problems such as demolding deformation. During the injection molding process, the operator needs to accurately adjust the process parameters such as injection pressure, injection speed, mold temperature and cooling time according to factors such as material characteristics and product requirements to ensure the stable quality of the bushing. ​
Post-processing​
After injection molding, there are often some burrs on the surface of the bushing. These burrs not only affect the appearance of the product, but also may cause damage to other parts during assembly. Therefore, they need to be removed manually or mechanically. Polishing is to further improve the surface finish of the bushing to meet higher quality standards. The cleaning process can remove impurities such as mold release agent and oil stains remaining on the surface of the bushing to ensure the cleanliness of the product. Inspection is the top priority in the post-processing process. Through various testing methods, such as appearance inspection, dimensional accuracy inspection, performance inspection, etc., the bushing is comprehensively evaluated. Only products that meet the quality standards can enter the next stage. ​
Factors affecting the injection molding process ​
Material properties ​
Different materials have different characteristics such as melting temperature, fluidity, shrinkage rate, etc., which have a significant impact on the setting of injection molding process parameters. For example, the fluidity of rubber materials is relatively poor, and higher injection pressure and temperature are required to smoothly fill the cavity; while the shrinkage rate of polyurethane materials is large. When designing the mold and controlling the injection molding process, shrinkage compensation needs to be fully considered to ensure the dimensional accuracy of the product. ​
Injection molding equipment performance ​
Parameters such as the screw diameter, injection rate, and clamping force of the injection molding machine will affect the stability of the injection molding process and product quality. An injection molding machine with excellent performance can more accurately control parameters such as injection pressure and speed, providing guarantee for the production of high-quality automotive electric strut bushing injection molding accessories. ​
Environmental factors​
The temperature, humidity and other environmental factors in the production workshop should not be ignored. Excessive humidity may cause raw materials to absorb moisture and affect the molding quality; temperature fluctuations may interfere with mold temperature and injection molding process, thereby affecting product performance. ​
Quality control of injection molding process​
Process monitoring​
During the injection molding production process, sensors and other equipment are used to monitor key parameters such as injection pressure, temperature, and screw position in real time. Once abnormal parameters are found, they are adjusted in time to avoid batch quality problems. ​
First piece inspection​
At the beginning of each batch of production, the first molded bushing is fully inspected, including appearance, dimensional accuracy, performance, etc. Only after the first piece inspection is qualified can batch production be carried out. ​
Sampling inspection​
During the production process, samples are inspected according to a certain proportion of products to timely discover possible quality fluctuations in the production process and take corresponding corrective measures.