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What is the difference between blister, blow molding and injection molding?
- Jun 21, 2018 -

What is the difference between blister, blow molding and injection molding?

-Blister packaging

A plastic processing technology, the main principle is the flat plastic hard sheet after heating and softening, the use of vacuum adsorption on the mold surface, cooling after forming, widely used in plastic packaging, lighting, advertising, decoration and other industries. Such
Blister packaging: plastic products are produced by blister process, and the products are packaged by corresponding equipment. It
Blister packaging products include: shell, tray, plastic box, synonyms are: vacuum hood, bubble cap and so on. The main advantages of plastic packaging are to save raw materials, light weight, convenient transportation, good sealing performance and meet the requirements of green packaging. It can package any special-shaped products, packing without additional cushioning material; the packaged products are transparent and visible, beautiful in appearance, easy to sell, and suitable for mechanized and automated packaging. It is convenient for modern management, saving manpower and improving efficiency.
Blister packaging equipment mainly includes: blister forming machine, punching machine, sealing machine, high frequency machine, folding machine. It
Packaged products can be divided into: plug-in card, suction card, double bubble shell, half bubble shell, folding shell, seventy percent off bubble shells, etc.

-Injection molding

Injection molding, that is, thermoplastic injection molding, this method is to melt plastic materials, and then injected into the membrane cavity. Once molten plastic enters the mold, it is molded into a certain shape by the cold mold cavity. The shape obtained is often the final product, and no other processing is needed before it is installed or used as the final product. Many details, such as raised parts, ribs and threads, can be molded in one step of injection molding. It
The injection molding machine has two basic parts: injection device and clamping device for melting and sending plastic into the mold. And the function of the mold device is: 1. make the die closed under the pressure of the injection; 2. melt the injection device before the injection mold of the plastic injection mold, and then control the pressure and speed to inject the melt into the mold. At present, there are two kinds of injection devices: screw type pre plasticizing device or two-stage device, and reciprocating screw. The screw preplasticizing device uses the pre plasticized screw (first stage) and then injecting molten plastic into the injection rod (level second). It
The advantages of the screw preplasticizing device are the constant quality of the molten material, the high pressure and the high speed, and the precise injection control (using the mechanical thrust device at both ends of the piston stroke). These advantages are needed for transparent, thin-walled products and high production rates. The disadvantages include uneven residence time (leading to material degradation), higher equipment costs and maintenance costs. It
The most common reciprocating screw injection device does not require plungers to melt and injecting plastics.


-Blow molding

Also known as hollow blow molding, a rapidly developing plastic processing method. The tube shaped plastic billet obtained by extrusion or injection molding is heated (or heated to softening state) and is placed in the open die. The compressed air is put into the blank immediately after the mould is closed, so that the plastic billet is swollen and pressed on the inner wall of the mold. After cooling off the mould, all kinds of hollow products are obtained. The manufacturing process of the blow molding film is very similar to the blow molding of the hollow products, but it does not use the mold. From the angle of the plastic processing technology, the molding process of the blow molding film is usually included in the extrusion. Blow molding technology began to produce low density polyethylene bottles during the Second World War. In the late 50s, with the birth of high-density polyethylene and the development of blow molding machine, blow molding technology has been widely applied.
The volume of the hollow container can reach thousands of liters, and some production has been controlled by computer. The plastic used for blow molding is polyethylene, polyvinyl chloride, polypropylene, polyester, and so on. Hollow containers are widely used as industrial packaging containers. According to the method of parison production, blow molding can be divided into extrusion blow molding and injection blow molding, and newly developed multi-layer blow molding and stretch blow molding.