What is the difference between blow molding process and injection molding process?

Blow-molded products are hollow; injection molding has an injection port, so a small part of the product will be cut off after molding, but if you look closely, you can still find it.

Injection molding is a method to make thermoplastic or thermoset molded plastics firstly plasticize evenly in a heated barrel, and then be pushed by a plunger or a moving screw into the cavity of a closed mold.



Injection molding applies to almost all thermoplastics. In recent years, injection molding has also been successfully used to mold certain thermoset plastics. Injection molding has a short molding cycle time, the mass of molded products can range from a few grams to tens of kilograms, and it can mold complex shapes, precise dimensions, and molded products with metallic or non-metallic inserts in a single process. Therefore, this method is highly adaptable and has high production efficiency.

Blow molding: A method of blowing the hot blanks closed in the mold into hollow products by gas pressure, or blowing the tube blanks into tube film without mold. This method is mainly used in the manufacture of various packaging containers and tubular films.


 
Any melt index of 0.04 to 1.12 is better hollow blow molding materials, such as polyethylene, polyvinyl chloride, polypropylene, polystyrene, thermoplastic polyester, polycarbonate, polyamide, cellulose acetate, and polyacetal resin, etc., of which polyethylene is the most widely used.

1. injection blow molding: The injection molding method is used to make the plastic into the bottom of the blanks, and then the blanks are moved to the blow molding mold and blown into hollow products.

2. Extrusion Blow Molding: The extrusion method is used to make the plastic into a bottom mold, and then the mold is moved to the blow molding mold to make hollow products.

3. Stretch blow molding: Stretch blow molding is a biaxial directional stretching blow molding, the method is to first longitudinal stretching, and then blow with compressed air to achieve horizontal stretching. Stretch blow molding can make the transparency, impact strength, surface hardness, and rigidity of the products greatly improved, suitable for polypropylene, polyethylene terephthalate blow molding. 4.

4. Blow molding film method: A method of molding thermoplastic film. The extrusion method is used to squeeze the plastic into a tube, and then with the help of the air blown into the tube to make it continuously expand to a certain size of the tubular film, after cooling, folded and wound into a double layer of flat film.