Guangdong distribution AKV230H2.0 Lansheng Granules Lansheng PA66

Durethan AKV230H2.0 901510

The factors affecting the molding shrinkage of thermoplastics are as follows:
2. When molding the plastic part characteristics, the molten material contacts the cavity surface and the outer layer is cooled immediately to form a low-density solid shell. Due to the poor thermal conductivity of the plastic, the inner layer of the plastic part cools slowly to form a high-density solid layer with large shrinkage. Therefore, those with wall thickness, slow cooling and high density layer thickness will shrink greatly. In addition, the presence or absence of inserts and the layout and quantity of inserts directly affect the direction of material flow, density distribution and shrinkage resistance, so the characteristics of plastic parts have a greater impact on the size and direction of shrinkage. Plastic warehouse network

Durethan AKV230H2.0 901510

The factors affecting the molding shrinkage of thermoplastics are as follows:
Molding condition The mold temperature is high, the molten material cools slowly, the density is high, and the shrinkage is large. Especially for the crystalline material, the shrinkage is larger because of the high crystallinity and large volume change. The mold temperature distribution is also related to the internal and external cooling and density uniformity of the plastic parts, which directly affects the size and direction of the shrinkage of each part. In addition, the holding pressure and time also have a greater impact on the shrinkage, and those with large pressure and long time have small shrinkage but large directionality. The injection pressure is high, the viscosity difference of molten material is small, the interlaminar shear stress is small, and the elastic rebound after demoulding is large, so the shrinkage can also be reduced moderately, the material temperature is high, the shrinkage is large, but the directivity is small. Therefore, adjusting mold temperature, pressure, injection speed, cooling time and other factors during molding can also appropriately change the shrinkage of plastic parts.

Durethan AKV230H2.0 901510

The factors affecting the molding shrinkage of thermoplastics are as follows:

During mold design, the shrinkage rate of each part of the plastic part shall be determined based on experience according to the shrinkage range of various plastics, the wall thickness and shape of the plastic part, the form, size and distribution of the feed inlet, and then the cavity size shall be calculated. For plastic parts and when it is difficult to master the shrinkage rate, the following methods should be generally used to design the mold:

① For plastic parts, the smaller shrinkage rate is taken for the outer diameter, and the larger shrinkage rate is taken for the inner diameter, so as to leave room for correction after mold testing.

② The form, size and forming conditions of the gating system are determined by mold test.

③ The plastic parts to be post-treated shall be subject to post-treatment to determine the size change (measured 24 hours after demoulding).

④ Correct the mold according to the actual shrinkage.

⑤ Try the mold again and modify the shrinkage value slightly by changing the process conditions appropriately to meet the requirements of plastic parts.
The content comes from the plastic library network