What is the plastic blow molding process

The steps and processes of different plastic blow molding processes are different. The following will be explained by Juxinchang editor:

1. Injection molding, stretching, blow molding

At present, injection molding stretch blow molding technology is more widely used than injection molding. This plastic blow molding processing method is actually injection blow molding, but it increases axial stretching, making blow molding easier and reducing energy consumption. Injection blowing can process products with a slightly larger volume than injection blowing. The volume of the blown container ranges from 0.2 to 20L, and its working process is as follows:

① First, inject the preform, the principle is the same as ordinary injection molding;

② Then transfer the billet to the heating and temperature control process to soften it;

③ Go to the blowing station and close the mold. The push rod inside the core stretches the billet along the axial direction, while blowing air to make the billet tightly adhere to the mold wall and cool down;

④ Go to the demolding station to pick up the parts.

Note - Pull Blow Process:

Injection molding billet → Heating billet → Mold closing, stretching and blowing → Cooling and taking parts

2. Extrusion blow molding

Extrusion blow molding is the most widely used method of plastic blow molding, with a wide range of processing from small products to large containers, automotive parts, aerospace chemical products, etc. The processing process is as follows:

① First, melt and mix the rubber material, and the melt enters the machine head to become a tube shaped billet;

② After the preform reaches the predetermined length, the blow molding mold is closed and the preform is sandwiched between the two halves of the mold;

③ Blow air into the billet to inflate it and make it tightly adhere to the mold cavity for molding;

④ Cooling products;

⑤ Open the mold and take away the hardened product.

Extrusion blow molding process:

Molten material → extruded billet → closed mold blow molding → mold opening and part taking

3. Injection blow molding

Injection blow molding is a plastic blow molding processing method that combines the characteristics of injection molding and blow molding. Currently, it is mainly used for blowing high-precision beverage bottles, medicine bottles, and some small structural parts.

① At the injection molding station, the preform is first injected using the same processing method as regular injection molding.

② After the injection mold is opened, the core rod and the blank are moved to the blow molding station.

③ The core rod places the billet between the blow molded molds and closes the molds. Next, compressed air is blown into the billet through the middle of the core rod, causing it to expand and adhere tightly to the mold wall, while cooling it down.

④ Open the mold, transfer the core rod to the demolding station, remove the blow molded part, and then transfer the core rod to the injection station for circulation.

1) The working process of injection blower

Blow molded billet → Injection mold opening to blown film station → Mold closing blow molding and cooling → Rotation to demolding station for part retrieval → Billet

2) Advantages and disadvantages of injection blow molding

Advantages:

The product has relatively high strength and high precision. There is no seam formed on the container and no need for trimming. The transparency and surface smoothness of blow molded parts are good, and they are mainly used in hard plastic containers and wide mouthed containers.

Disadvantages:

According to the editor of Juxinchang, due to the high equipment cost and energy consumption of plastic blow molding machines, they generally only form containers with relatively small volumes (less than 500ml) and cannot form containers with complex shapes, making it difficult to form elliptical products.