What are the 4 stages of injection molding?

1. Overview

 When the factory starts injection molding production, it will purchase the corresponding raw materials according to the product requirements. Commonly used raw materials are ABS\PC\PP, etc. After the raw materials are ready, we start our first step: plasticization. The main purpose of the plasticization process is to heat and melt the raw materials (plastic particles) into a flowable liquid form.

2. Detailed process

Feeding: Feed the plastic particles into the barrel of the injection molding machine through the feeding port.

Heating: A heater inside the barrel heats the plastic pellets above the melting point, usually between 150°C and 350°C, depending on the type of plastic used.

Mixing and shearing: The screw rotates in the barrel, mixing and shearing the molten plastic to ensure that the material can be uniformly and consistently transferred to the next step.

3. Key Factors

Temperature control: ensures that the plastic is fully melted but not excessively degraded.

Screw speed: affects plasticization and mixing effects.

1. Overview

The injection stage is the process of injecting the molten liquid into the mold.

2. Detailed process

Mold Closure: The two halves of the mold are tightly closed to form a cavity.

Injection: The screw moves forward, injecting the molten plastic into the mold cavity through the nozzle.

Pressure Holding: During the cooling and solidification of the plastic, a certain pressure is maintained to ensure complete filling and dimensional stability.

3. Key Factors

Injection speed: affects filling time and filling quality.

Holding time: affects the dimensional stability and internal stress of the product.

1. Overview

The cooling phase is the process by which the plastic cools and solidifies within the mold.

2. Detailed process

Cooling time: Determine the appropriate cooling time based on product thickness and material properties.

Cooling medium: Use water or other cooling medium to exchange heat through the cooling channels in the mold.

3. Key Factors

Cooling rate: affects the crystallinity and internal stress of the product.

Mold temperature: affects the surface quality and dimensional accuracy of the product.

1. Overview

The demoulding stage is the process of removing the solidified plastic product from the mold.

2. Detailed process

Mold opening: The two halves of the mold separate.

Ejection: The ejection mechanism pushes the product out of the mold.

Removal: The product is removed from the mold manually or by a robot.

3. Key Factors

Ejection force: Ensure that the product is smoothly released from the mold without excessive deformation.

Ejection position: avoids scratches or damage to the product surface.

The four stages of the injection molding process - plasticization, injection, cooling and demolding - are each critical and affect the quality and performance of the final product. By deeply understanding and optimizing these stages, manufacturers can improve production efficiency, reduce scrap rates, and produce high-quality plastic products.

Hopefully this article will help you better understand the four key stages of the injection molding process. If you have any questions or need further advice, please feel free to contact us.