Haochen20 years of focus on multimode cavities and small spacing hot runner

It has been successfully used to process various types of plastic materials. For example: PP, PE, PS, ABS, PBT, PA, PSU, PC, POM, LCP, PVC, PET, PMMA, PEI, ABS/PC, etc. Any plastic material that can be processed using a cold runner mold can be processed using a hot runner mold. Therefore, the characteristics of plastics are particularly important. For example, attention should be paid to ablation temperature, pressure, viscosity, specific heat, etc. Because the scope of plastics is very broad, we cannot deepen it, but we will elaborate on its knowledge.

1. Preconditions for hot runner forming of molds

The following are the forming prerequisites for ordinary plastic. For each type of plastic, there may be differences in the relative forming area, but the process analysis is the same. Therefore, for excellent mold designers, the forming area and processing characteristics of each type of plastic should be investigated.

2. The activity of melting plastic in the hot runner of the mold

The active forms of ordinary fluids (such as water, oil, etc.) are all carried out according to the Newtonian definition. Plastic melt, which appears to be a common fluid, is actually a long and short Newtonian fluid. For example, in Newtonian fluids, although there is a change in shear stress, its viscosity remains unchanged. And when the shear stress changes in plastic melt, there is also a clear change in viscosity. For example, in Newtonian fluids, when the pressure increases from 1 to 10, the outflow rate increases by 10 times. Using plastic melt for the same implementation, when the pressure is added from 1 to 10, the outflow can be increased by 100 times, 500 times, or even 1000 times (depending on the different plastic).

3. Selection of Plastic Materials for Mold Hot Runner

At the beginning of the design of the finished product, the plastic used should be chosen, but most of them have not incorporated the mold into their thinking. But if possible, the selected materials should make the manufacturing of the mold simple. The dimensional accuracy of those with low forming shortening rate (PS, ABS, PC) is easier to achieve. However, those with high forming shortening rates (PP, PE, POM) are more difficult to achieve dimensional accuracy (the service life of the mold is 1/6 of the service life of the formed product). Those with relatively high viscosity during activities (such as ABS) have a lower tendency for the solution to flow into cracks, while those with low viscosity (such as PA, POM) are more likely to enter even with small gaps.

Those with lower forming temperatures (PS, etc.) are more likely to form and have a faster forming cycle, while those with higher forming temperatures (PC) are slower