Shear Rate of Air Cooler Mould During High-speed Filling
In the injection moulding process of the Air Cooler Mould(FURNITUREMOULD), the hot runner is used in conjunction with the mould and plays a very important role.
High-precision and high-quality products can be easily produced by using hot runner. For injection moulding raw materials with poor fluidity, the air cooler mould can obviously improve the fluidity of the raw materials by using hot runner to ensure smooth injection moulding production.
The nozzle tip of hot runner nozzle is easily worn away by glass fiber. After the nozzle tip is worn away, there is too much cold glue in the gate area, so the injection pressure is not enough to rush out, and no glue will come out. So many companies can't get glue out of their hot mouths after using them several times. If the nozzle tip is made of high-speed steel or other materials, the high-speed steel is poor in heat conduction, and the temperature difference between the nozzle tip and the runner is too large, cold material will be generated as well as injection moulding is difficult.
The air cooler mould is filled at high speed. When filling at high speed, the shear rate is relatively high, and the viscosity of plastic decreases due to shear thinning, which reduces the overall flow resistance. Local viscous heating will also make the thickness of the cured layer thinner. Therefore, in the flow control stage, the filling behavior often depends on the volume to be filled. That is, in the flow control stage, due to high-speed filling, the shear thinning effect of the melt is often very large, while the cooling effect of the thin wall is not obvious, so the effect of the speed has the upper hand.
Generally speaking, the strength of the weld line produced by the air cooler mould in the high-temperature region is better, because the high-molecular chain has better mobility and can penetrate and wrap each other. In addition, the temperatures of the two melts in the high-temperature region are relatively close, and the thermal properties of the melts are almost the same, increasing the strength of the weld region. On the contrary, in the low temperature region, the welding strength is poor.
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