Shaping methods calendering

The first shaping method is a steady continuous process. It is among the oldest methods, and is used extensively in the rubber and plastics industries. It includes the classic calendering, as well as various continuous coating operations, such as knife and roll coating. 

An important step in the manufacture of any plastic product is the fabrication or the shaping of the article. Most polymers used as plastics when manufactured are prepared in pellet form as they are expelled from the reactor. These are small pieces of material a couple of millimeters in size. This resin can then be heated and shaped by one of several methods. Thermoset materials are usually compression molded, cast, or laminated. Thermoplastic resins can be injection molded, extruded, or blow molded most commonly, with vacuum forming and calendering also used but to a lesser extent. 

Mixed compounds are almost always transformed into products with required shapes and dimensions. There are several methods to accomplish this. Tubes, solid round profiles and profiles with irregular, often complex shapes, are prepared by extrusion. Sheets, slabs, and rubber-coated fabrics are made by calendering. 

Fluorosilicone compounds can be processed by the same methods used for silicone elastomers based on PDMS. They can be milled, calendered, extruded, and molded. A large proportion of fluorosilicone compounds is used in compression molding. Molded parts produced in large series are made by injection molding, and parts with complex shapes are produced by transfer molding. Calendering is used to produce thin sheets and for coating of textiles and other substrates. 

Different methods may be used to obtain the desired shape of the material. Sheets with thicknesses between about 0.5 and 2 mm may be produced by calendering. These may be densified further by pressing between two plates, which may be heated. Other possible processing methods include extrusion and injection molding or pressing. 

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