Industry as a plastic molding powder, granules and dispersions, etc., are generally not pure resin, which are added with a variety of additives to improve the performance of plastic products and reduce costs. Thermoplastics and thermoset plastics processing methods vary greatly, thermoplastic materials processing methods are: extrusion, calendering, thermoforming, rotational molding, injection molding, hollow molding and casting. Thermoset plastics processing methods include: compression and compression injection molding, lamination molding, winding molding and reaction molding. Several major molding methods are described below.
Injection molding injection molding is with the help of screw or plunger thrust, will have been plasticized plastic melt at a certain pressure and rate into the mold cavity, after cooling and curing to obtain products. Injection molding occupies an important position in the whole plastic production, except for a few kinds of plastics, almost all plastics can be injection molding.
With the development of injection molding process, injection molding machine to large-scale, miniaturization, high-speed, high automation and specialization of the direction of development. After the use of microcomputer control, plastic parts size error can be ± 0.03% ~ ± 0.05% below, equipped with a high-precision injection mold can be realized after high-precision plastic injection molding.
Extrusion molding Extrusion molding, also known as extrusion molding, it is in the extrusion molding machine through the heating, pressurization so that the material in a flowing state continuously through the head of the different shapes of the mouth mold to mold, like daily life with the noodle press, dough from the end of the noodle press into the other end of the noodle press out of the long noodle. Extrusion molding can process almost all thermoplastics and some thermosetting plastics. Extrusion molding products include: solid profiles, pipe-type profiles, plates, hollow profiles, open profiles, composite profiles and inlaid profiles. Extrusion molding in the plastic molding process occupies an important position. It not only has high labor productivity, but also has dense extruded products, as long as the replacement of the head can change the cross-section shape of the product to produce a variety of products.
Hollow blow molding Most of the thermoplastics can be used for blow molding products, of which high-density polyethylene is used most. Hollow blow molding is under the action of compressed air, so that the high elasticity of the molten plastic parison expansion and transformation, and then through the cooling of the shape to obtain a small diameter of the hole in the product. Blow-molded film is the most widely used in the production of plastic film, it is like a child blowing a balloon, molten plastic flow through the head of a cylindrical thin tube extrusion, from the center of the head into the compressed air, the thin tube will be blown for a larger diameter tubular film (commonly known as the tube bubble), cooled rolled into products.
Rotational molding, also known as rotational or rotational molding, is the amount of powdered resin in the mold heating and plasticizing, while the mold rotation, with the help of the resin's own gravity so that it is uniformly distributed on the surface of the mold cavity, and then cooled, demolded to get products. With this method of large hollow products, such as tanks, tanks and boats, etc. is more economical.
Foam molding Foam is the whole of the plastic contains countless microporous. The most commonly used plastics are polyurethane, polystyrene, polyvinyl chloride, polyethylene and so on. Foam is first produced using different foaming methods, and then processed into foam products using molding methods such as injection, extrusion, molding and calendering.
Plastic injection molding machine