What technology is used in blow molding processing

Extrusion blow molding is a method of manufacturing hollow thermoplastic parts. The well-known blow molded objects include bottles, barrels, cans, boxes, and all containers for packaging food, beverages, cosmetics, pharmaceuticals, and daily necessities. Large blow molded containers are commonly used for packaging chemical products, lubricants, and bulk materials.

Other blow molded products include balls, corrugated tubes, and toys. For the automotive manufacturing industry, fuel tanks, car shock absorbers, seat backrests, center brackets, and armrest and headrest coverings are all blow molded. For the mechanical and furniture manufacturing industry, blow molded parts include shells, door frames, frames, pottery jars, or boxes with an open face.

polymer

The most common blow molded extruded plastic material is high-density polyethylene, and most milk bottles are made from this polymer. Other polyolefins are also often processed through blow molding. According to their applications, styrene polymers, polyvinyl chloride, polyester, polyurethane, polycarbonate, and other thermoplastic materials can also be used for blow molding.

Recently, engineering plastics have been widely accepted in the automotive industry. The selection of materials is based on mechanical strength, weather resistance, electrical performance, optical performance, and other properties.

workmanship

3/4 of blow molded products are manufactured through extrusion blow molding processing. Extrusion technology forces materials to pass through a hole or mold to manufacture products.

The extrusion blow molding process consists of 5 steps: 1. Plastic preform (extrusion of hollow plastic tubes); 2. Close the flap mold on the embryo, clamp the mold and cut off the embryo; 3. Inflate the cold wall of the mold cavity, adjust the opening, and maintain a certain pressure during the cooling period; 4. Open the mold and remove the blown parts; 5. Trim the edges to obtain the finished product.

extrusion

Polymer blending is defined as a process of upgrading a polymer or polymer system through melt blending. The mixing process ranges from the addition of a single additive to the treatment of multiple additives, polymer alloys, and reactive mixing.

It is estimated that one-third of polymer production in the United States involves blending. The mixed ingredients can be customized according to the performance requirements of the final application. Mixed products have mixed properties, such as high gloss and excellent impact strength, or precision moldability and good stiffness.

The mixed polymer is usually pelletized for further processing. However, the industry is increasingly interested in combining blending with the next process, such as profile extrusion, to avoid reheating the polymer.

mix

People use various types of melt mixing equipment, from roller mills and batch mixers to single screw and twin-screw extruders. Continuous mixing (extruder) is the most commonly used equipment because it can provide products of consistent quality and reduce operating costs. There are two types of mixing: distributed mixed materials can be evenly distributed in the mixing process without the need for high shear stress. This type of mixture is called extensional mixing or laminar mixing.

Dispersed mixing, also known as strong mixing, involves applying high shear stress to break down the solid that has agglomerated. For example, when the additive pellets are crushed, the actual particle size decreases.

According to the editor of Juxinchang, in the blow molding process, mixing operations often require two types of mixing in one process.