Increasing the injection pressure can reduce the shrinkage of the product. This is because the pressure is increased, the injection speed is increased, and the filling process is accelerated. On the one hand, the melt temperature is increased by the shear heat of the plastic melt, and the flow resistance is reduced; on the other hand, the melt temperature can also be obtained.
In the state of high pressure and low flow resistance, it enters the pressure-preserving feeding stage earlier. Especially for thin-walled plastic parts and small gate plastic parts, due to the fast cooling rate, the filling process should be shortened as much as possible. The higher holding pressure and cavity pressure make the products in the cavity dense and shrinkage, especially the pressure in the pressure-holding stage has a greater influence on the shrinkage rate of the product. This can be explained by the fact that the molten resin is compressed under the molding pressure. The higher the pressure, the greater the amount of compression that occurs, and the greater the elastic recovery after the pressure is released, so that Plastic mould manufacturers the size of the plastic part is closer to the size of the cavity, so the amount of shrinkage The smaller. However, even for the same product, the pressure of the resin in the cavity is not uniform in each part; the injection pressure is different in the portion https://www.nbtianke.com where the injection pressure is difficult to act and the portion where it is easy to act.
In addition, the pressure of each cavity of the multi-cavity mold should be designed uniformly, otherwise the shrinkage rate of the products of each cavity will be inconsistent. Reasonable tolerances of various plastic parts and corresponding mold manufacturing tolerances can be reasonably determined, which not only brings convenience to mold manufacturing, but also reduces waste and improves economic efficiency.
In the state of high pressure and low flow resistance, it enters the pressure-preserving feeding stage earlier. Especially for thin-walled plastic parts and small gate plastic parts, due to the fast cooling rate, the filling process should be shortened as much as possible. The higher holding pressure and cavity pressure make the products in the cavity dense and shrinkage, especially the pressure in the pressure-holding stage has a greater influence on the shrinkage rate of the product. This can be explained by the fact that the molten resin is compressed under the molding pressure. The higher the pressure, the greater the amount of compression that occurs, and the greater the elastic recovery after the pressure is released, so that Plastic mould manufacturers the size of the plastic part is closer to the size of the cavity, so the amount of shrinkage The smaller. However, even for the same product, the pressure of the resin in the cavity is not uniform in each part; the injection pressure is different in the portion https://www.nbtianke.com where the injection pressure is difficult to act and the portion where it is easy to act.
In addition, the pressure of each cavity of the multi-cavity mold should be designed uniformly, otherwise the shrinkage rate of the products of each cavity will be inconsistent. Reasonable tolerances of various plastic parts and corresponding mold manufacturing tolerances can be reasonably determined, which not only brings convenience to mold manufacturing, but also reduces waste and improves economic efficiency.
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