Fluoropolymer Tube Extrusion

Tube extrusion is quite similar to the wire insulation process. Processing details depend on the size and type of the tube. Tube can be manufactured by both in-line and crosshead dies. FEP tubing can be produced with outside diameters as low as 1 mm to over 20 mm. This range is broken into three processing zones based on the size of the outside diameter small, medium, and large. The sizing die determines the outside diameter of the extrusion output and the line speed determines the inside diameter. Take-up speed and the die gap, and the difference between the inside diameter of the die and the outside diameter of the tip, set the wall thickness. 

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Uses Melt-processable fluoropolymer for extrusion (wire coating, tubing, film), inj. molding, blow molding, compr. molding, rotomolding, electrostatic coating, industrial... 

Extrusion is one of the most popular processes for fabricating parts from fluoropolymers. Fiber and filament account for a relatively small share of all fluoropolymers extrusion. The principal end products are wire insulation, tubing, film, and sheet. Fluo-ropolymer films are widely used in release, surface protection, and packaging. Sheet and profile extrusions account for a small share of fluoropol5uners consumption. 

Monoaxially and biaxially oriented films of fluoropolymer are made by melt extrusion of the resin into flat webs or tubes. The main function of orientation is to enhance the mechanical properties of the film such as tensile break strength and tear resistance. The decision to orient is usually made according to the requirements of the end use for mechanical properties. All process surfaces that contact molten fluoropolymers must be corrosion resistant because of the formation of corrosive compounds such as HF and HCl from the high-temperature degradation of these plastics. 

Synthetic rubbers, EPM/EPDM, nitrile, polychloroprene (neoprene), epichlorohydrin, and polyacrylate have good oil resistance, heat stability, and chemical resistance. Fluoropolymers are used in oil and gas wells 20,000 ft (6096 m) deep. These depths can have pressures of 20,000 Ib/in (137.5 MPa) which cause extrusion failures of down-hole seals by forcing the rubber part out of its retaining gland. TFE/propy-lene jackets protect down-hole assemblies which consist of stainless steel tubes that deliver corrosion-resistant fluid into the well. 

Polyvinylidene fluoride is an engineering resin that represents the basis of melt processable fluoropolymers and is used primarily in injection molding of fittings and molded components as well as extrusion of profiles such as pipes, tubing and sheets. The current commercial resins are limited in their market applications due to their molecular structure, which is essentially linear. Their viscosity can only be controlled by adjusting the Mw. Therefore, a balance between a low viscosity for ease of processing and a high viscosity for sag resistance cannot be achieved in practice. 

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