I have to manage a factory because of my new job which engaged in plastic injection molding and whose products are plastic parts. Our materials are mainly PP, TPE, and nylon. I didn't study materials science or injection molding process before, so I hope to understand some basic knowledge of plastic injection molding process. For example: What are the characteristics of different materials during injection molding, and what needs to be paid attention to to ensure molding? What are the common requirements and knowledge of injection molding process? What are the common defective plastic parts and how to improve them?

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Newcomer with grateful thanks for advice!

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The so-called injection molding refers to a method of injecting heated and molten material into a mold and cooling and solidifying to obtain a molded product. The specific process is to feed the granular or powdered plastic into the heated barrel through the hopper of the injection molding machine. When it becomes plasticized and melted, the screw will begin to press, and then it will be injected into the low-temperature closed mold through the nozzle. At this time, the material will cool and harden to form a given shape of the mold cavity. Finally, the mold is opened and the colloid is taken out, and the injection molding process is completed.

Injection molding is a commonly used method in plastic molding processing. It is suitable for all thermoplastics (thermoplastics are plastics that can be heated, melted, cooled and hardened repeatedly within a specific temperature range, such as ABS, PP, PE, PC, PA , POM) and certain thermosetting plastics, and most plastic products are manufactured by injection molding. In addition, injection molding is also called injection molding because it is a molding method that combines injection and molding. The molding cycle of the injection molding process is very short, usually a few seconds to a few minutes. The quality of the molded products ranges from a few grams to tens of kilograms. It has strong adaptability, high production efficiency, high speed, and automatic operation. The characteristics of molding are suitable for the production of plastic products with complex shapes, precise sizes, diverse colors, large production volumes, and metal or non-metal inserts.

Four conditions for high-quality injection products:
1. Use a reliable injection molding machine for processing.
2. Use auxiliary equipment that meets the requirements, such as dryers, coolers, crushers and blenders, because according to the requirements of the injection molding process, it is necessary to ensure that the plastic raw materials are completely dry and free of moisture. Therefore, the raw materials must be dried by a dryer before injection molding.
3. Choose appropriate raw materials. New plastic raw materials purchased from outside and recycled secondary materials need to be fully mixed in an appropriate ratio before they can be used in production.
4. Hire high-quality technical personnel to adjust the machine. Before the molding process, the operator must test the mold to check the quality of the mold and adjust the appropriate process parameters.
5.Finally, according to the design requirements of the plastic product, the operator needs to color the entire injection molded part. At this time, the corresponding colorant needs to be added to the plastic raw material, and then it is fully and uniformly mixed with the raw material. This is a very important step. , Must be taken seriously.