Transparent plastic blow molding processing tips

In mold planning, attention should be paid to the following issues (including product planning) in order to avoid poor plastic molding caused by poor activity or uneven cooling, resulting in appearance defects and transformation. Generally, in mold planning, the following points should be noted:

a) The wall thickness should be as uniform as possible, and the demolding angle should be satisfactory.

b) The transition should be gradual. Smooth transition and avoid sharp corners. Sharp edges occur, especially in PC products, there must be no gaps.

c) Gate. The runner should be as wide and short as possible, and the gate orientation should be set according to the shortened condensation process. If necessary, a cold material well should be added.

d) The surface of the mold should be bright and have a low roughness (preferably less than 0.8).

e) Exhaust hole. It is necessary to be satisfied with the groove in order to timely discharge air and gas from the melt.

f) Except for PET, the wall thickness should not be too thin, usually not less than 1mm.

Questions to pay attention to in terms of blow molding processing technology (including the requirements of injection molding machines).

In order to reduce internal stress and external quality defects, attention should be paid to the following issues in injection molding technology.

a) Special screw and injection molding machine with independent temperature controlled nozzle should be selected.

b) The injection temperature should be higher than the injection humidity, provided that the plastic resin does not differentiate.

c) Injection pressure: usually higher to overcome the disadvantage of high viscosity of the molten material, but too high pressure can cause internal stress to form demolding due to difficulty and deformation.

d) Injection speed: In the case of satisfactory mold filling, it is usually recommended to be low, and it is best to choose a multi-stage injection of slow, fast, and slow.

e) Pressure holding time and forming cycle: under the condition of satisfactory product filling without any depression or bubbles; It is advisable to keep it as short as possible to minimize the time when the molten material stays in the barrel.

f) Screw speed and back pressure: On the premise of satisfying the plasticization quality, it should be as low as possible to avoid the possibility of delamination.

g) Mold temperature: The cooling quality of the product has a great impact on the quality, so the mold temperature must be able to accurately control its process. If possible, the mold temperature should be higher.

Other questions arise because in order to prevent deterioration of surface quality, it is usually advisable to use as little release agent as possible during injection molding; When using recycled materials, it shall not exceed 20%.

All products, except for PET, should undergo post-processing to eliminate internal stress, PMMA should have a dry hot air cycle of 70-80t for 4 hours; PC should be cleaned with air and glycerin.

Liquid paraffin and other materials are heated at 110-135 ℃, depending on the product, with a maximum demand of over 10 hours. And it is necessary for PET to achieve outstanding mechanical properties through the process of biaxial stretching.