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Analysis of the relationship between fep tube extrusion molding process and quality

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Analysis of the relationship between fep tube extrusion molding process and quality

  • Categories:Industry news
  • Author:PFA tube lady
  • Origin:PFA tube lady
  • Time of issue:2008-04-19 15:21
  • Views:

Analysis of the relationship between fep tube extrusion molding process and quality

  • Categories:Industry news
  • Author:PFA tube lady
  • Origin:PFA tube lady
  • Time of issue:2008-04-19 15:21
  • Views:

  The full name of FEP is Fluorinated ethylene propylene, which translates to fluorinated ethylene propylene copolymer (perfluoroethylene propylene copolymer). The English trade name: Teflon* FEP, is a class of chemical substances. FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene. The melting point of FEP crystal is 304°C and the density is 2.15g/CC (grams/cubic centimeter). FEP can be applied to soft plastics, and its tensile strength, wear resistance, and creep resistance are lower than many engineering plastics.

  

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Figure 1 Source of fep spiral tube: Miss Teflon tube

  FEP has better processing performance. The insulation layer of the wire and cable can be covered by the usual extrusion method. The following is what needs to be prepared before extrusion of FEP pipe: 

  1) Feeding: Before FEP extrusion, it is advisable to pre-bake at 120°C for about 3 hours. 

  2) Conductive core preheating: In order to ensure the uniform temperature inside and outside the extruded FEP insulation layer, the conductive core should be preheated to 300-350°C. 

  3) The temperature distribution of the extruder: The temperature distribution of the extruder generally rises linearly from 280°C (feeding port) to 380°C (head);

  4) The stretch ratio of the die sleeve: should be selected in the range of 50-200. 

  5) Screw speed: After adjusting the screw speed in cooperation with the temperature, do not change frequently during the FEP resin extrusion process, and adjust it slightly if necessary.

  6) Mould die mouth insulation: the insulation area should cover the entire stretching area, and the insulation temperature should be 350-380℃ to avoid stress caused by the rapid cooling of the surface of the FEP cone before it is formed, which will lead to insulation cracking.

  7) Cooling of insulated wires: The wires extruded from the extruder are cooled by water. The distance between the die and the water tank should be relatively close, and it is recommended that it be no more than 20cm.

  The product forms before FEP resin processing and molding are:

  1. Pellets, used for extrusion molding and injection molding;

  2. Dispersion liquid, used for dipping and coating;

  3. Powder material, used for electrostatic spraying.

  Below we mainly understand several molding processing methods of FEP.

  1. Melt extrusion molding

  2. Compression molding: heating, pressurizing and plasticizing; cooling, pressurizing to shape

  3. Blow molding

  4. Vacuum forming

  5. Injection molding

  6. Coating processing

  7. Electrostatic spraying

  (Video of inserting fep spiral tube)

  The extrusion quality of FEP hose has a certain relationship with the following related parameters. A certain factor may cause the quality of FEP pipe extrusion to be different from the ideal.

  1. Temperature

  Extrusion molding temperature includes barrel temperature, plastic temperature, screw temperature, generally we measure barrel temperature. The temperature is controlled by the heating and cooling system. Due to the screw structure, the instability of the heating and cooling system, and the change of the screw speed, the temperature of the extruded material fluctuates in the radial and axial directions, which affects the quality of the product. The strength of the product is different. Residual stress, the surface is dull and dull. To ensure product quality, the temperature should be stable.

  2. Pressure

  Due to the structure of the screw and barrel, the resistance of the machine head, filter screen, and filter plate causes pressure inside the plastic. The pressure change is shown in the figure, and the pressure also fluctuates.

  3. Extrusion rate

  The mass or length of the plastic extruded from the die of the extruder per unit time. Factors affecting the extrusion rate: head resistance, screw and barrel structure, screw speed, heating and cooling systems, and plastic characteristics. But when the product has been determined, the extrusion rate is only related to the screw speed. The extrusion rate also fluctuates, which affects the product geometry and size.

  There are fluctuations in temperature, pressure, and extrusion rate. In order to ensure product quality, the screw should be designed correctly, the heating and cooling system and the stability of the screw speed should be controlled to reduce parameter fluctuations.

  Shenzhen DanKai Technology Co., Ltd. (ShenZhen DanKai Technology Co.,ltd.), whose predecessor was Dongguan Dandi Insulation Material Co., Ltd. Fluoroplastic Material Factory, which was established in 1998, specializes in FEP, PFA, PTFE and other fluoroplastic pipes. R&D, production and sales of rod, sheet and film products and other insulating materials. The company has a senior R&D team with international standards and a production line of fluorine plastic products imported from abroad. Some fluoroplastic products have passed ISO9001, SGS, FDA certification, and have been fully affirmed by domestic and foreign cooperative customers such as Huawei, Foxconn, Midea, ZTE, Intel, and AirTAC. The main products of the company are: ①Tubes: Ptfe tube, Fep tube, Pfa tube, Pvdf tube; ②Heat shrinkable tube: Ptfe heat shrinkable tube, Fep heat shrinkable tube, Pfa heat shrinkable tube, Pvdf heat shrinkable tube; ③Plate rod Membrane: Ptfe board and rod film, Fep board and rod film, Pfa board and rod film, Pvdf board and rod film; ④Insulation materials: silica gel, PE, PVC, UPE, etc.; ⑤Special category: PFA imported connector, spiral tube, spring tube , Rotary cut tube, welding rod, tee, straight-through, gasket, joint, taper rod, flared tube, sealing tube, braided tube, bellows, etc. At the same time, fluorine plastic products of various specifications can be customized and processed according to customer requirements.

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