What are the parameters needed to buy a bottle blowing machine?
In the actual production, PET resin and molding equipment for a given, it can be used to determine the appropriate steps of melt temperature: the temperature reduced gradually, to bottle mist began to appear, and then increase the temperature, just to fabricate transparent bottle when the temperature is appropriate melt temperature. In general, the temperature of the PET melt should be selected at 280 degrees centigrade. Increasing the injection rate and decreasing the barrel temperature is beneficial to form the bottle embryo with high transparency and low acetaldehyde content. The high injection pressure should be used to stabilize the filling process in the initial short time, and the injection with low pressure can achieve better results.
The parameters that should be paid attention to when making bottle embryo are: melt temperature is an important parameter for PET molding, and the selection should be appropriate to ensure the transparency of bottle embryo and control acetaldehyde production at the same time.
The screw design of injection molding machine has a great influence on the melting, mixing uniformity and melt temperature of PET. The injection molding of PET bottles shall be made of screws with low shear and low compression ratio (about 2. 1). The feed section shall be longer and the transition section and measurement section shall be shorter.When designing hot runner, temperature control and flow balance should be considered. Flow equilibrium means that the melt must be uniformly filled with individual cavities at the same flow rate, pressure drop, and time. Therefore, the mold cavity shall be symmetrically arranged, and the diameter of the flow and the filling nozzle shall be increased appropriately from the middle to the sides.
When the nozzle is filled with the mold, the temperature of the melt will be reduced because of the close to the mold of the bottle at low temperature, thus affecting the transparency of the bottom of the embryo. To avoid this, set a heating ring around the nozzle, or try to take proper thermal insulation between the nozzle and the mold. In addition, the diameter of the runner and gate is appropriately increased, and the transparency of the bottom of the embryo is also increased.
