The reason of water stain pattern produced by injection moulding processing

In the process of injection moulding, due to the change of temperature, pressure, cooling time and other factors on the surface of the mould, the plastic material on the surface of the mould can not be completely fused, forming traces similar to water stains, which is water streaks. Water stains not only affect the appearance of the product quality, but also may lead to product performance degradation, therefore, to find out the causes of water stains and take corresponding measures is very necessary. So, what are the reasons for water streaks in injection moulding?

1. Uneven mould surface temperature

Uneven mould surface temperature is one of the main reasons for water streaks in injection moulding. In the injection moulding process, the surface temperature of the mould has a great influence on the melting and fluidity of the plastic material. If the temperature of the mould surface is not uniform, it will lead to different flow speeds of the plastic material on the mould surface, which will result in the formation of water streaks.

To solve this problem, the following measures can be taken:

(1) Optimise the mould design so that the temperature distribution on the mould surface is more uniform;

(2) Use thermostatic equipment, such as mould thermostats, to keep the mould surface temperature stable;

(3) Regularly check and repair the mould to ensure that the mould surface temperature sensor works properly.

2. Insufficient cooling time

Cooling time is another important factor that affects the water stain pattern of injection moulding process. If the cooling time is not enough, the solidification of plastic material on the mould surface is slow, which will easily lead to the production of water stains.

In order to ensure product quality, we need to adjust the cooling time according to the melting point of the plastic material and the temperature of the mould surface. In addition, we can also shorten the cooling time by the following methods:

(1) Improving the heat dissipation efficiency of the mould surface, such as increasing the cooling channels and using efficient coolant;

(2) Reduce the temperature of the mould surface, but be careful not to be too low, so as not to affect the fluidity of the plastic material;

(3) Optimise the injection process parameters, such as injection speed and pressure, in order to improve the cooling rate of plastic materials.

3. Improper selection of plastic materials

The choice of plastic material will also affect the water stain pattern of injection moulding process. Different plastic materials have different properties such as melting point, fluidity and shrinkage. If the choice is not appropriate, it may lead to the production of water stains.

Therefore, we need to choose the right plastic material according to the performance requirements of the product and the production process. In addition, we can also improve the performance of plastic materials by changing their formulations and additives to reduce the generation of water streaks.