First of all, compared with the standardized molds of c […]
First of all, compared with the standardized molds of conventional products, the molds of thin-walled products have undergone major changes in the mold structure, gating system, cooling system, exhaust system and demolding system. Mainly in the following aspects.
The structure of the mold is to withstand the high pressure during molding, and the rigidity and strength of the thin-walled molding mold should be high. Therefore, the movable and fixed templates of the mold and their supporting plates are heavy, and the thickness is usually thicker than that of the traditional mold. There are more support columns, and there may be more internal locks in the mold to ensure accurate positioning and good side support to prevent bending and offset. In addition, the high-speed injection speed increases the wear of the mold, so the mold should use a higher hardness tool steel, and the hardness of the high wear and high erosion area (such as the gate) should be greater than HRC55.
The gating system forms thin-walled products, especially when the thickness of the product is very small, a large gate should be used, and the gate should be larger than the wall thickness. In the case of sprue, a cold slug well should be set to reduce the gate stress, assist in filling, and reduce the damage when the product is removed from the gate. To ensure sufficient pressure to fill the thin cavity, the pressure drop in the runner system should be minimized.
For this reason, the runner design is larger than the traditional one, and the residence time of the melt must be limited to prevent the resin from degrading and degrading. When it is a mold with multiple cavities, the balance requirements of the gating system are much higher than those of conventional molds. It is worth noting that two advanced technologies have also been introduced into the gating system of thin-walled product molds, namely hot runner technology and sequential valve gate technology.