Slow first and then fast injection, that is, first-stag […]
Slow first and then fast injection, that is, first-stage slow injection, when it reaches a set position, second-stage fast injection, the starting point is usually set at the beginning of injection into the cavity At the early stage of filling. According to different problems, sometimes it is necessary to switch to the second stage when a small part of the glue (about 10-15MM) is inserted, and some need to be transferred to the second stage when the glue is a little bit (about 3MM), and sometimes It must be transferred to the second stage before the glue is added.
With the first-level slow-spraying glue, the melted glue can be filled smoothly from the beginning, which is beneficial to prevent air trapping, gas lines and explosion-proof shooting, spiral or folding (snake-shaped) glue injection. The secondary fast injection is helpful to overcome the resistance to ensure the filling, reduce the temperature drop of the melt, and prevent the dull color and material shortage of the injection molded parts.
What problems can it solve?
Using this tuning technique, it can often be used to solve many problems such as water breath marks and cow feces patterns, or to solve some conflicting problems, as follows:
1. It is used to solve the problem of bull feces and water trapping on thick and large pieces. For example, the number one problem in toy injection molding is the cow shit pattern and water trapping pattern of thick PVC parts. 2. It is used to solve the problem of easy to produce air lines or jet lines at the water inlet. For example, the water inlet breath pattern of PC parts is difficult. 3. Solve the problem of burnt glue and dull color around the water inlet. 4. It is used to prevent other problems when it needs to fill the mold quickly to get the whole material. For example, the problem of air lines or shooting lines around the water inlet and so on.
Of course, in the production, the adjuster can also increase the number of injection levels in this process in order to solve some other problems that arise during the injection process according to the actual situation. For example, when there is a gas pattern in a certain position in the middle of the injection molded part, it is necessary to add a slow injection level during the rapid injection process, and then switch back to the fast injection after filling the position where the gas pattern is generated. Since rapid injection is easy to cause air trapping, scorching, and frontal problems, a slow and low pressure filling and pressure holding process is required in the later stage of injection.
This tuning technique can be said to be one of the several commonly used tuning techniques that are indispensable in injection molding production. Whether it will be used, whether it is used well or not, is essentially different for the level of technology.