The main process parameters of injection molding

2021-03-23 12:50:31 admin

Based on years of experience in injection molding processing, the main process parameters of injection molded parts can be summarized into several categories, including: barrel temperature, melt temperature, injection molded part mold temperature, injection pressure, these four major factors. If there is no influence of these four factors, then injection molding is impossible to talk about. From the above analysis, we can see the importance of temperature for injection molding, as well as the important role of injection pressure for injection molding. The following is an analysis of the elements of each injection molding process, which can help us better understand the process and results of injection molding process.


Barrel temperature: Effective control of the barrel temperature is an important part of ensuring the quality of plastic products. The temperature setting of the injection cylinder depends on the melt temperature, screw speed, back pressure, injection volume and injection molding cycle. If you have no experience in processing a specific grade of plastic, please start with the lowest setting. In order to facilitate control, the shooting cylinder is divided into zones, but not all are set to the same temperature. When the barrel temperature is low and is far from the set value, the temperature should be raised quickly, and when the barrel temperature is close to the set value, the temperature should be raised slowly. Before starting the injection, make sure that the hydraulic oil, hopper closure, injection mold and injection cylinder are all at the correct temperature.


Melt temperature: It is necessary to know that the melt temperature plays a major role in the flow properties of the melt, and the specific melting point must be controlled by yourself. Since plastic has no specific melting point, the so-called melting point is a temperature range in the molten state. The molecular chain is also one of the reasons. The structure and composition of the plastic molecular chain are different, so the influence on its fluidity is also different. The rigid molecular chain is affected by temperature more obviously, such as PC, PPS, etc., while the flexible molecular chain such as: PA, PP The fluidity of, PE, etc. is not obvious by changing the temperature, so adjust the reasonable temperature of the injection molded part according to the different materials.


Mold temperature of injection molded parts: Some plastic materials require higher mold temperature due to high crystallization temperature and slow crystallization speed, so we have to consider the relationship between crystallization and mold temperature. Some require higher temperature or lower temperature due to the need to control size and deformation, or demoulding, so the temperature can change the appearance of the part, etc. In addition, PC generally requires 60 degrees or more, and PPS in order to achieve better To improve the appearance and fluidity, the mold temperature sometimes needs to be above 160 degrees. Therefore, the mold temperature of injection molded parts has a nearly decisive effect on improving the appearance, deformation, size, and rubber mold of the product.


Injection pressure: This force is the resistance required by the melt to overcome the advancement. This force will directly affect the size, weight and deformation of the product, etc., and almost play a decisive role in the mold temperature. Different plastic products require different injection pressures, and the shapes of products shaped by different pressures are also very different. For materials such as PA and PP, increasing pressure will significantly improve their fluidity. The injection pressure determines the density of the product, that is, the appearance of gloss. On the other hand, some injection molded parts will become more difficult to fill with the injection molded part, and the pressure of the injection molded part will increase.


All in all, the main process parameters of injection molding are objectively existing. Three temperature parameters, barrel temperature, melt temperature, injection mold temperature, and an injection pressure. That is, we can call it 3+1 parameters. For the barrel temperature, in the injection molding process, one item to be noted is that if the temperature is greater than the set value, the temperature should be raised quickly, and then slow down when the temperature is close to the set value. The melting temperature is different for different molecular chains. The mold temperature of the injection molded part, and its temperature plays a key role in the change of the shape. In the injection molding plant, when the injection pressure is achieved, the pressure and the appearance of the product maintain a positive influence.