Views: 73 Author: Site Editor Publish Time: 2023-02-07 Origin: Site
Comparison of injection blow molding and extrusion blow molding cosmetic plastic bottles The difference between the two process methods of extrusion blow molding and injection blow molding plastic bottles is: injection molding.
Comparison of injection blow molding and extrusion blow molding medicinal plastic bottles. The difference between the two process methods of extrusion blow molding and injection blow molding of plastic bottles is: In injection molding, the mold used to form the plastic bottle should include a male mold. With the female mold.
The plastic melt is injected into the mold cavity by the injection machine under high pressure. When the cavity is opened, the male mold must be removed from the female mold to eject the bottle. In extrusion blow molding, it is necessary to It is formed by an extruder head. The blow mold is mainly composed of two halves of a female mold, generally without a male mold, and the parison is inflated with injected compressed air.
1. Blow molding can form products with very thin walls. Such products cannot be molded by injection. Blow molding can form products with complex, irregular and integral shapes. When injection blow molding is used, it is necessary to produce After two or more pieces, they are combined by snap fitting, solvent bonding or ultrasonic welding.
2. The molecular weight of blow molding grade plastics (such as PE) is much higher than that of injection molding grade plastics. In this way, blow molding products have higher impact toughness and high environmental stress cracking resistance, which is suitable for the production of large-capacity plastic bottles. Very advantageous.
3. Since the blow mold is only composed of a female mold, the thickness of the bottle can be changed by simply adjusting the die gap or extrusion conditions. This is very beneficial for products that cannot accurately calculate the required wall thickness in advance. For injection molding, the cost of changing the wall thickness of the product is much higher.
4. The cost of blow molding machinery (especially blow molds) is low. For example, when molding the same product, the cost of blow molding machinery is about 1/3 or 1/2 of that of injection molding machinery, and the production cost of the product is also lower. In blow molding, the parison is formed under a lower pressure through the extruder head and inflated under low pressure (mostly 0.2 to 1.0 MPa), so the residual stress of the product is small, and it is resistant to stretching, impact, and bending. It has high performance against various strains such as the environment, and has better performance. In injection blow molding, the plastic melt must pass through the mold runner and gate under high pressure (15～140 MPa), which will lead to Uneven stress distribution.