Tubular plastic blanks that are obtained by extrusion or injection molding for thermoplastic resins, hot (or heating to soften the state), placed in the open mold , immediately after the closed mold in the mold into the compressed air, so that the plastic billet blown and close to the mold wall, After cooling demoulding, all kinds of hollow products are obtained. Blow molding Film manufacturing process in principle and hollow products blown very similar, but it does not use the mold, from the plastic processing Technology classification of the angle, blow molding film molding process is usually included in extrusion. Blow moulding process During the Second World War, it began to produce a small bottle of low-density polyethylene . In the late 50, with the birth of high-density polyethylene and the development of blow molding machines, the blow moulding technology was widely used. The volume of hollow containers can reach thousands of liters, and some production has been controlled by computer. Suitable for blow molding plastics have polyethylene, polyvinyl chloride, polypropylene , polyester and so on, the resulting empty containers are widely used as industrial packaging containers.
Plastic Mold Common Sense
Extrusion blow Molding is a method of manufacturing hollow thermoplastic parts. Well-known blow-moulding objects include containers for bottles, barrels, cans, cartons and all packaged food, beverages, cosmetics, pharmaceuticals and commodities. Large blow-moulding containers are usually used in the packaging of chemical products, lubricants and bulk materials. Other blow moulding products include balls, bellows and toys. For the automotive industry, fuel tanks, car shock absorbers, seat backs, central brackets, and handrails and headrest covers are blown. For mechanical and furniture manufacturing, blow molded parts have housings, door frames, racks, pottery cans or boxes to have an open face.
Blow Molding Polymer
The most common plastic blow moulding is high-density polyethylene , which is made of most milk bottles. Other polyolefin are also often processed by blow moulding. Styrene polymers, polyvinyl chloride, polyester, polyurethane, polycarbonate and other thermoplastic plastics can also be used for blow moulding.
Engineering Plastics have recently been widely accepted in the automotive industry. Material selection is based on mechanical strength, weathering resistance, electrical properties, optical properties and other properties.
Blow Molding Process
3/4 of blow molding products are made by extrusion blow molding method. Extrusion is the forced item to make a product from a hole or a mold.
The extrusion blow molding process is composed of 5 steps: 1. Plastic type embryo (extruding of hollow Plastic pipe); 2. The mould is closed on the embryo, clamping die and cutting off the embryo; 3. To the cavity of the cold wall blowing expansion type, adjust the opening and maintain a certain pressure during the cooling; 4. Open the mould and remove the blown part; 5. Trim the flying edge to get the finished product.
Polymer mixing is defined as a process by which a polymer or polymer system can be raised to a higher grade by a melt mixture. Mixing process from single additive to a variety of additive treatment, polymer alloy and reactive mixing, the scope of a wide range. It is estimated that one-third of the U.S. polymer production to be mixed. 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 die-plasticity and good stiffness.
Well-blended polymers are usually cut into grains for further processing. Increasingly, however, the industry is interested in combining blending with the next process, such as the profile extrusion, which avoids heating the polymer again.
People use various types of melt mixing equipment, from roller mixer and batching mixer to single screw and twin-screw extruder. Continuous mixing (extrusion machine) is the most commonly used equipment, because he can provide consistent quality products, and can reduce operating costs. There are two kinds of mixing types: distributed mixtures can be distributed evenly without high shear stress in mixed ingredients. This type of mixture is known as an extensibility mixing or laminar mixing.
The dispersed mixture is also called a strong mixing, in which high shear stress is applied to break the cohesive solids. For example, when the additive pellet is smashed, the actual particle size becomes smaller.
Blending operations often require two types of blending in one process.
Blow Molding Application Scope
Usually people's daily necessities such as: bottles , cans, baby supplies, sporting goods, etc.
Related Industry Knowledge
- Injection system
- Clamping system
- Hydraulic system
- Electrical control
- Heating / cooling
- Lubrication system
- Safety monitoring
- Before operating the main points
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