In injection molded parts, the complete technology is an indispensable engineering technology. It involves transforming plastic into products that retain their original performance. The important process conditions for injection molded parts are temperature, pressure, and corresponding time for plasticization, flow, and cooling.
It can be roughly divided into three aspects here: temperature control, pressure control, and molding cycle.
There are a total of 3 points for temperature control: barrel temperature, nozzle temperature, and mold temperature as follows:
1. Barrel temperature:
Depending on different conditions, different barrel temperatures are selected. The temperature that needs to be controlled during the injection molded parts process includes the barrel temperature, which mainly affects the plasticization and flow of plastic. Each type of plastic has a different flow temperature. For the same plastic, due to different sources or grades, its flow temperature and decomposition temperature are different, which is caused by the different average molecular weight and molecular weight distribution. The plasticization process in different types of injection machines is also different, so the choice of barrel temperature is also different.
2. Nozzle temperature:
In general, the nozzle temperature is slightly lower than the highest barrel temperature to prevent drooling. If the temperature is too low, the early solidification of the melt will cause the nozzle to block, or the early solidified material will be injected into the mold cavity, affecting the performance of the product. Suitable temperature can ensure the performance and other characteristics of the product.
3. Mold temperature:
Generally speaking, the mold temperature has a great influence on the intrinsic performance and appearance quality of the product, and can be said to be one of the most important factors. The mold temperature is determined by the crystallinity of the plastic, the size and structure of the product, the performance requirements, the temperature of the melt, the injection speed and pressure, and the molding cycle, etc.
As we all know, pressure control is one of the important courses. The pressure during injection molded parts includes plasticization pressure and injection pressure, which directly affect the plasticization and product quality of the plastic. Here are the following points for plasticization pressure and injection pressure.
1. Plasticizing pressure:
When using a screw type injection machine, the pressure that the melted material at the top of the screw receives when the screw rotates back is called the plasticizing pressure, also known as the back pressure. This pressure plays an important role in molding. The magnitude of this pressure can be adjusted through the relief valve in the hydraulic system. In the injection process, when the plasticizing pressure is increased, the temperature of the melt will be increased but the plasticizing speed will decrease if the screw speed remains unchanged.
2. Injection pressure:
In current production, it is foreseeable that almost all injection machine's injection pressure is based on the pressure applied to the plastic by the plunger or top of the screw. The role of injection pressure in injection molded parts is to overcome the flow resistance of the plastic from the barrel to the mold cavity, give the melt the rate of filling the mold, and compact the melt.
We know that the time required to complete an injection molded parts process is called the molding cycle, also known as the molding cycle. The molding cycle directly affects production efficiency and equipment utilization. Regardless of the role played, in the production process, on the premise of ensuring quality, all related time in the molding cycle should be shortened as much as possible. This can improve production efficiency, which is also a characteristic of the molding cycle. In injection molded parts, every interval of time is shortened, and the overall quality and efficiency will naturally improve.