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High-gloss injection molding technology creates a "smooth appearance"

How to produce shell products without melt marks, no flow marks, no flow lines, no shrink marks, and high surface light is especially important for flat panel TVs, computer LCD monitors, air conditioners, and automotive interior parts. This problem can be solved very well by using high-gloss injection molding technology.

The process principle of high-gloss injection molding is: after the mold is heated and clamped before the mold clamping and clamping, the temperature is up to the set condition, that is, the injection is performed. The mold continues to maintain a high temperature during the injection process, which allows the mold to maintain good fluidity in the mold during injection. After the injection is completed, when the pressure is cooled, the mold is cooled, and the cooling time of the product can be greatly shortened, thereby improving the production efficiency.

Steam-free high-gloss injection molding technology is currently an advanced production process in China. Because this technology greatly improves the surface quality and surface strength of the product, and can eliminate the subsequent spraying or painting process, which not only protects the environment and the personal health of the operator, but also reduces the process, eliminating the need for expensive secondary Processing costs save energy and materials while significantly reducing production costs.

The traditional approach is to use a mold temperature machine to warm the mold, but the shortcomings of this method are as follows:

1) It is unable to meet the needs of rapid heating and rapid cooling in high-gloss injection molding;

2) The temperature rise is small, and the weld marks on the surface of the product can only be reduced and cannot be eliminated;

3) The higher the hardness of the plastic, the worse the fluidity. Therefore, the hardness of the surface of the product can only meet the needs of the actual use of the HB level;

4) When the mold is warmed up, it will expand by heat, and when it cools down, it will shrink again, making the clamping force very unstable. It is easy to cause various defects such as product dissatisfaction, charring, and internal stress.

The steam high-gloss injection molding technology developed on the basis of this process has been improved for the above defects:

1) This technology opens the water pipe in the mold, needs to pass steam when heating, and needs to pass cold water when cooling. After cooling, the residual air is blown out by compressed air to ensure rapid heating and cooling;

2) to eliminate the failure of various products such as weld marks, water marks and lack of glue;

3) Due to the large temperature rise, the hardness of the surface of the product is greatly improved by using plastics of H or even 2H hardness level;

4) When the pipe is opened inside the mold, only the inner surface of the mold is heated or cooled, and the overall expansion of the mold is small, thereby reducing various product defects caused by the instability of the clamping force.

To produce high-quality high-gloss products, it is necessary to match injection molding machines, molds, special-purpose plastics for high-light products for temperature control equipment, boilers, and cooling devices.

1. The configuration of the press

1) The clamping mechanism is rigid; it has to be heated and cooled continuously throughout the production process. Therefore, the clamping mechanism of the injection molding machine is required to have rigidity and strength to ensure the accuracy and stability of the clamping force. Thereby ensuring the surface quality of the product.

2) Large-mold injection molding machine: When this process is used, gas-assisted injection can no longer be used, so the clamping force required to produce the product will be relatively large.

3) Select a small amount of shot glue according to the situation: If you are producing flat panel TV, LCD screen frame and other products, you don't need a large amount of shot glue. When choosing an injection molding machine, try to choose a small shot size injection molding machine. The actual weight of the product is optimal between 30% and 80% of the theoretical injection amount of the injection molding machine. If the amount of glue injected by the machine is too large, the rubber compound will be decomposed separately in the barrel for a long time, and defects such as silver wire will be generated on the surface of the product.

4) The plastic used in the production of high-gloss products with special screw has higher hardness and relatively lower melt index, so it is better to plasticize the screw. At the same time, the shearing of the screw can not be too large, otherwise the rubber will be easily decomposed.

2. Mold configuration

1) The inner surface of the mold requires a very high finish to ensure the surface quality of the product;

2) The piping inside the mold must be reasonable to ensure rapid heating and cooling;

3) The pipe inside the mold should have good thermal conductivity;

4) Due to the need to continuously increase and decrease the temperature during the production process, the steel used in the mold is better;

5) Pay special attention to the maintenance of the mold during use to ensure that it is dry and dust-free.

3. Temperature control equipment configuration

1) Temperature control should be very accurate, which is an important guarantee for product quality;

2) The temperature control equipment reacts very quickly to ensure high production efficiency.

4. Special plastic

When producing products with high surface quality, commonly used plastics are ABS, PC+ABS or PMMA+ABS. Among them, ABS has the lowest hardness, and PMMA+ABS has the highest hardness, up to H or even 2H. However, the higher the hardness, the lower the melt index. The fluidity will be worse, so you can choose the right plastic according to your production needs.

With the increasing use of plastic parts and the increasing awareness of environmental protection and safety, steam-free high-gloss injection molding has gradually become the frontier and popular technology in the future of injection molding.

High-gloss injection molding technology creates a "smooth appearance"