Process Principle and Requirements of High-gloss Injection Molding
The mold is heated before and during mold clamping. After completing mold clamping, the injection will start when the temperature reaches the set conditions. The mold continues to maintain a high temperature during the injection process. So the rubber can maintain good fluidity in the mold during injection. After finishing the injection, during the pressure holding and cooling time, we can cool down the mold. It can greatly shorten the cooling time of the product, thereby improving the production efficiency.
To produce high-quality high-gloss products, injection molding machines, molds, temperature control equipment, special plastics for high-gloss products, and boilers, cooling devices, etc. are required:
- The configuration of the plastic machine
①The rigidity of the clamping mechanism must be good:
The temperature rises and falls continuously throughout the production process. Therefore, the clamping mechanism of the injection molding machine must have good rigidity and strength to ensure the accuracy and stability of the clamping force. So as to ensure the surface quality of the product.
②Replace the injection molding machine with large clamping mode:
When using this process, we can no longer use the gas-assisted injection. Thus, the necessary clamping force will be relatively large.
③Replace a smaller injection volume according to the situation:
For example, when producing flat-panel TVs, LCD screen frames and other products, try to choose an injection molding machine with a small injection volume. The actual weight is best between 30% and 80% of the theoretical injection volume of the injection molding machine. If the amount of machine injection rate is too large, the glue material will decompose separately if it stays in the barrel for a long time. What’s more, defects like silver wire will appear on the surface of the product.
④The plastic used in the production of high-gloss products with a special screw has high hardness and a relatively low melt index. So the screw is required to be plasticized. At the same time, the shear of the screw shouldn’t be too large, otherwise the rubber will be easily decomposed.
① The inner surface of the mold requires a very high finish to ensure the surface quality of the product.
②The starting pipeline inside the mold must be reasonable to ensure rapid heating and cooling.
③The pipeline inside the mold should have good thermal conductivity.
④For the need to keep heating and cooling during the production process, the steel for mold msut be great.
⑤Pay special attention to the maintenance of the mold to ensure it is dry and dust-free.
Configuration of temperature control equipment
①The temperature control must be very accurate. Because it is an important guarantee for product quality.
②The response of temperature control equipment should be very fast to ensure higher production efficiency.
When producing products with higher surface quality, the commonly used plastics are ABS, PC + ABS or PMMA + ABS. Among them, ABS has the lowest hardness. While PMMA + ABS has the highest hardness, which can reach H or even 2H. But the higher the hardness is, the lower the index. The fluidity will become worse, so you can choose the appropriate plastic according to the production needs.
Steam traceless high-gloss injection molding technology greatly improves the surface quality and surface strength of the product. Besides, it cancels the subsequent spraying or painting and other processes. That not only protects the environment and the health of the operators, but also reduces the processes and eliminates the expensive secondary processing costs. Then, it would greatly reduce the production cost while saving energy and materials.