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Home / How do plastic injection molding machines process various plastic raw materials?

How do plastic injection molding machines process various plastic raw materials?

2025/01/22 By Topstar

Plastic Injection Molding Machines 9-13

In 2024, Topstar launched special plastic injection molding machines for MIM injection molding to address the difficulties of metal injection molding. At the same time, it also launched two innovative solutions for the automotive lighting industry: automotive lighting silicone headlight dual-material and automotive PMMA thick-walled headlight injection molding unique solutions. In these two solutions, the plastic injection molding machines perfectly solved the requirements of different plastic raw materials for injection molding. Here, we will detail how plastic injection molding machines process raw plastic materials to achieve high cleanliness and high-quality product requirements, such as for various optical and medical products.

How does a plastic injection molding machine process PC raw materials?

Manufacturers widely use PC, a thermoplastic known for its strength, impact resistance, and optical transparency, to produce high-performance automotive, electronics, and optics parts. However, due to the high viscosity of PC and its easy degradation at high temperatures,

To efficiently process a PC, manufacturers equip the plastic injection molding machine with a special screw, such as a bimetallic screw.
The screw design is essential for uniformly melting the material and preventing degradation. In addition, manufacturers must carefully control the injection pressure (typically around 1800kgf/cm²) to ensure that the molten plastic properly fills the mold cavity without causing defects. For applications that require additional strength, such as automotive structural parts, adding glass fibers can further enhance the mechanical properties of polycarbonate. You must adjust plastic injection molding machine settings, including screw speed and injection pressure, based on the percentage of glass fiber added to the material to maintain optimal flow characteristics and prevent damage to the screw or mold.

plastic injection molding machine process PC raw materials

Processing ABS with Plastic Injection Molding Machine

ABS is commonly used in automotive parts, consumer goods, and electrical housings. Manufacturers process ABS in plastic injection molding machines using nitrided screws and barrels with moderate shear rates to ensure that the material fully melts. It has a relatively low melting point compared to other plastics, so the machine temperature must be between 200°C and 240°C. This ensures that the plastic reaches a viscosity suitable for molding. The injection pressure required to process ABS is generally lower than that of materials such as polycarbonate, generally around 1400kgf/cm² or more, allowing for better molding process control. In addition to temperature and pressure control, the cooling rate is essential when processing ABS, as rapid cooling can cause warping or stress inside the part. You should control the mold temperature to achieve optimal cooling without compromising the part’s integrity.

Processing ABS with Plastic Injection Molding Machine

Processing PP Raw Materials Injection Molding

PP is commonly used in packaging, automotive parts, and household goods due to its chemical resistance and high flexibility. Certain factors must be considered when processing PP using a plastic injection molding machine to ensure optimal flow and performance. A key factor to consider when processing PP is the need for higher injection speeds to overcome its low viscosity. You can achieve this by selecting an injection molding machine with high injection speed capabilities. Manufacturers often use specialized screws, such as nitrided screw barrels, to improve the melting efficiency and material flow of PP. The injection pressure of PP is also usually in the range of 1400kgf/cm², depending on the complexity of the part and the mold design.

Processing PP Raw Materials Injection Molding

Injection molding of PMMA raw materials

PMMA is a sensitive material, especially under pressure and temperature conditions during the injection molding. Injection molding machines typically use injection pressures above 1800 kg/cm², often requiring unique components to extend the machine’s life and maintain high-quality production. Manufacturers frequently use chrome-plated screws for PMMA injection molding because they are durable and wear-resistant due to the abrasive nature of the material. The chrome plating helps prevent the surface of the screw from wearing out due to friction and heat generated during the injection molding process.

In addition, chrome-plated screws have excellent resistance to the corrosive effects of PMMA heat and moisture absorption. This is particularly important to ensure that the screw maintains its smoothness and operating efficiency, thereby improving the overall performance of the plastic injection molding machine. Using chrome-plated screws also helps minimize the risk of contamination, ensuring that the final product maintains its optical clarity and surface finish.

Processing PE Raw Materials with Plastic Injection Molding Machines

When processing PE raw materials, injection pressures above 1400 kg/cm² are often used. These high pressures help to effectively fill the mold cavity, ensuring that the material flows into all the intricate details of the mold. Such high pressures also require careful attention to temperature control, as PE is sensitive to temperature changes during the injection molding process. To alleviate the challenges of processing PE under high pressure and high-temperature conditions, plastic injection molding machines often use nitrided screw barrels to improve the wear and corrosion resistance of metal parts. In addition, nitrided screw barrels have better thermal stability than standard steel barrels, which helps maintain consistent temperature conditions during processing. At the same time, it can also improve the mechanical properties of the barrel and help reduce the risk of material contamination during the molding process.

Use different screws and injection pressures for other materials.

For injection molding of different materials, it is necessary to select the appropriate screw design, adjust the injection pressure, and carefully control the mold and barrel temperature. At the same time, Topstar can also propose dedicated plastic injection molding machine solutions according to different application products to optimize the molding process to ensure high product quality and efficient production.

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