What is the difference between
blow molding process and injection molding process,and three common blow molding processes for
cosmetic containers Blow molding products are hollow; Injection molding because there is an injection port, there will be a small part of the molded product that is not needed. There will be a process to cut it off, but it can be found if you observe it carefully.
Injection molding is a method to make the thermoplastic or thermosetting molding compound plasticize evenly in the heating barrel, and then push it into the mold cavity of the closed mold by the plunger or moving screw.
Injection molding is applicable to almost all thermoplastics. In recent years, injection molding has also been successfully used to form some thermosetting plastics. The molding cycle of injection molding is short, and the quality of molded products can range from a few grams to tens of kilograms. It can form molded products with complex shape, accurate size and metal or non-metal inserts at one time. Therefore, this method has strong adaptability and high production efficiency.
Blow molding: it is a method to blow the hot parison closed in the mold into hollow products by gas pressure, or blow the tube parison into tube membrane without mold. The method is mainly used for manufacturing various packaging containers and tubular films.
Those with melt index of 0.04 ~ 1.12 are excellent hollow blow molding materials, such as polyethylene, polyvinyl chloride, polypropylene, polystyrene, thermoplastic polyester, polycarbonate, polyamide, cellulose acetate and polyacetal resin, among which polyethylene is the most widely used.
- Injection blow molding: the plastic is first made into a bottomed parison by injection molding, and then the parison is moved to the blow mold to blow into a hollow product.
- Extrusion blow molding: the plastic is first made into a bottomed parison by extrusion method, and then the parison is moved to the blow mold to blow into a hollow product.
- Stretch blow molding: stretch blow molding is a kind of blow molding of biaxial directional stretching. Its method is to stretch the mold longitudinally first, and then blow it with compressed air to achieve transverse stretching. Stretch blow molding can greatly improve the transparency, impact strength, surface hardness and rigidity of products. It is suitable for blow molding of polypropylene and polyethylene terephthalate.
- Blown film method: a method of forming thermoplastic film. The plastic is extruded into a tube by extrusion method, and then it is continuously expanded to a certain size of tubular film with the help of air blown into the tube. After cooling, it is folded and wound into a double-layer flat film.
Three common blow molding processes for cosmetic containers In the manufacturing process of cosmetic containers, you may often hear professional terms such as extrusion blow molding (EBM), injection stretch blow molding (isbm) and injection blow molding (IBM). In this paper, we briefly explain the differences of these three processes and supporting related products for product managers for your reference when selecting products in the superior product chain:
Extrusion blow molding (EBM)
Extrusion blow molding is a method of manufacturing hollow thermoplastic parts. Well known blow molding objects include bottles, barrels, cans, boxes and all containers for packaging food, beverages, cosmetics, drugs and daily necessities. Large blow molded containers are usually used for the packaging of chemical products, lubricants and bulk materials.
- Process cost: processing cost (medium), single piece cost (low)
- Typical products: container packaging of chemical products, container packaging of consumer goods and container packaging of drugs
- Output suitable: only suitable for mass production
- Quality: high quality, the wall thickness is exactly the same, and the surface treatment is suitable for smooth, frosted and textured
- Speed: fast, average 1-2 minutes per cycle
Injection blow molding (IBM)
Injection blow molding process: firstly, the injection machine injects the molten plastic into the injection mold to form the tube blank, which is formed on the hollow punch with micropores on the peripheral wall; Then move it into the blow mold while it is hot; Then close the mold and inject compressed air from the pipe of the mandrel to inflate the parison and stick it to the cavity wall of the mold; Finally, after pressure maintaining, cooling and shaping, release compressed air and open the mold to take out the plastic parts.
- Process cost: processing cost (medium), single piece cost (low)
- Typical products: container packaging of chemical products, container packaging of consumer goods and container packaging of drugs
- Output suitable: only suitable for mass production
- Quality: high quality, the wall thickness is exactly the same, and the surface treatment is suitable for smooth, frosted and textured
- Speed: fast, average 1-2 minutes per cycle
Injection stretch blow molding (isbm)
Injection stretch blow molding, also referred to as injection stretch blow molding, is to inject the preform by the injection molding machine, stretch the hot preform longitudinally, and then inject compressed air to stretch it transversely to obtain the product with the same shape as the mold cavity. According to the product forming process, it can be divided into one-step injection, drawing and blowing process and two-step injection, drawing and blowing process.
- Process cost: processing cost (medium), single piece cost (low)
- Typical products: container packaging of chemical products, container packaging of consumer goods and container packaging of drugs
- Output suitable: only suitable for mass production
- Quality: high quality, the wall thickness is exactly the same, and the surface treatment is suitable for smooth, frosted and textured
- Speed: fast, average 1-2 minutes per cycle
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