What is the process of plastic injection?

Injection molding is one of the important plastic molding processes in modern manufacturing industry, and is widely used in the production of various plastic products. From the selection of raw materials to the inspection of the final product, every step is crucial to ensure the quality and performance of the product. This article will detail the key steps of injection molding, revealing the whole process from raw material to finished product. Jiangzhi is a full-service contract manufacturer based in China, providing high-end customized manufacturing solutions for international brands and OEM in all walks of life.


1. Preparation of raw materials

  • Raw Material Selection: Select the appropriate plastic material according to the product requirements, such as ABS, polypropylene (PP), polyethylene (PE), nylon, etc.
  • Raw material drying: Some plastics (such as nylon and ABS) are highly hygroscopic and must be dried to remove moisture to ensure that no bubbles or defects are produced during molding.

2. Mold Preparation

  • Mold Design and Manufacturing: Molds are made according to the product design. Molds are usually made of steel or aluminum and have the negative shape of the product. The mold usually consists of two parts: the fixed mold and the moving mold.
  • Mold Cleaning and Installation: Install and fix the mold on the injection molding machine, check the mold for any damage or impurities.

3. Commissioning of the injection molding machine

  • Setting injection parameters: according to the material characteristics and mold requirements, set the injection temperature, injection speed, injection pressure, cooling time and other parameters.
  • Trial mold debugging: carry out trial mold operation, debug the parameters of the injection molding machine to ensure that the quality of the product meets the standard, to avoid defects.

4. Feeding

  • The plastic granules are added to the charging port of the injection molding machine through the hopper, and the plastic granules are then heated to a molten state.

5. Plasticizing and Injection

  • Plasticizing: The molten plastic is plasticized under the rotation of the screw of the injection molding machine to achieve a uniform flow state.
  • Injection: The plasticized molten plastic is rapidly injected into the inner cavity of the mold by the pressure of the screw moving forward, filling all the voids of the mold.

6. Pressurization and cooling

  • Holding Pressure: After the molten plastic is injected into the mold, a certain pressure is maintained to ensure that the plastic completely fills the mold and to reduce shrinkage.
  • Cooling: The mold is kept cool for a set period of time to allow the plastic to gradually solidify. This process ensures that the finished product has the desired hardness and shape.

7. Mold opening and demolding

  • Mold Opening: After cooling is complete, the mold is opened and the product is exposed.
  • Demolding: The finished product is removed from the mold either by a mechanical device or manually. For complex molds, it may be necessary to use ejector pins or other aids to assist in demolding.

8. Post-processing

  • Fly edge removal: The product may have excess edges (fly edges) after demolding, which need to be cut, sanded, etc. to remove the fly edges.
  • Surface treatment: Depending on the product requirements, surface treatment such as spraying, coating, printing, polishing, etc. may also be carried out.
  • Assembly and Inspection: Some products require further assembly and functional testing to ensure that the final product meets quality standards.
Through the above process, it can be seen that injection molding requires rigorous operation and control, and each link has its own specific requirements. The strict implementation of each step ensures the stability and consistency of product quality, laying the foundation for the production of high-quality plastic products. This systematic process is an important guarantee for efficient and accurate modern manufacturing.



地点: 中国

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