In recent years, there has been an increasing demand for smaller products in various industries such as electronics, watchmaking, and others. There is a growing need for precision in the injection molding process, especially for small plastic injection parts.
Under such circumstances, the research on micro-injection molding technology faces a significant challenge – how to meet the design requirements of micron-level dimensions while maintaining good appearance and performance?
Below is a simple analysis and introduction of the differences between micro-injection molding and traditional injection molding in terms of mold process technology.
For micro-injection molding, there are generally two development trends in mold processing technology. The first is the use of mirror spark erosion. To ensure high precision, it is best to use graphite electrodes for electrical discharge machining (EDM) since graphite electrodes have much less wear compared to ordinary copper electrodes.
The second commonly used method is electroforming. Electroforming technology can guarantee high precision. However, it has the drawback of a long processing cycle as each cavity needs to be processed independently. Moreover, if there is slight damage during production, it cannot be repaired and only the damaged cavity needs to be replaced.
In vertical injection molding molds, mold temperature is also a crucial parameter in micro-injection molding.
The current widespread approach is to borrow the idea from high-gloss plastics and utilize imported rapid heating and cooling systems.
In theory, a high mold temperature can help with micro-injection molding. For example, it can effectively prevent difficulties in filling thin walls and insufficient material. However, excessively high mold design temperature can lead to new problems, such as prolonged economic cycles and post-molding shrinkage deformation.
Therefore, it is of great importance to introduce a temperature control system for new molds, where the mold temperature can be increased during the injection molding process (exceeding the melting point of the plastic material) to allow the melt to fill the mold cavity rapidly. After that, the mold temperature can be quickly reduced to a temperature lower than the plastic’s heat deformation temperature, and then the vertical injection molding machine can eject the product.
