1. Application (general manufacturing materials in parentheses): aseptic cold-fill bottle caps (PE), hot-fill bottle caps (PE), normal temperature non-pressure (water) bottle caps (PE) and steam caps (PP)
2. In terms of structure, it can be divided into inner plug type and gasket type, and there are bottle caps whose sealing gasket is drip plastic.
3. From the processing technology, it can be divided into injection molding type and compression molding type.
4. According to the material, it can be divided into HDPE and PP.
5. From the connection bridge, it is completed by injection molding and trimming at one time.
6. From the size, it is divided into 28 teeth, 30 teeth, 38 teeth, 44 teeth, 48 teeth, etc.
The shrinkage of the anti-theft bottle cap is mainly due to the shrinkage of the volume, the surface material at the wall thickness is pulled in, and the surface of the finished product appears sunken after cooling. Shrinkage is the most common adverse phenomenon that occurs on the surface of the finished product, most of which occur at the wall thickness.
1. Technological factors
(1) The holding pressure is not enough to overcome the strong resistance in the flow channel during the holding stage, so that the pressure in the membrane is insufficient and feeding cannot be performed.
(2) The injection speed and pressure holding speed are too slow, so that the fluidity of the melt is not enough, and the speed is relatively slow. The melt that enters the cavity first cools faster, and it is too late to use the holding pressure for feeding. At this time, a higher temperature can be used. Injection pressure or increased plastic.
(3) The pressure holding time is too short, causing the melt to flow back before the gate solidifies, resulting in insufficient feeding of the product.
(4) The back pressure of the storage material is not enough, and the screw retreats quickly, so that the melt is not dense and the shrinkage space of the product is large.
(5) The mold temperature and hot runner temperature are too high, and the cooling time is prolonged. When the cooling is not enough, the shrinkage of the product is large.
2. Mold factors
(1) The trapped air in the mold is poorly exhausted, resulting in residual air in the cavity, less molten material for feeding, and large shrinkage of the product. The mold should be maintained and the exhaust groove should be added.
(2) The demoulding is not smooth, resulting in the product being pulled and dents, the mold should be maintained, the mold should be polished or the thimble should be added.
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