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Molding Compression Technology And Injection Technology Of Fluoroplastic
- Jun 17, 2018 -

Molding Compression Technology of Fluoroplastic

 

Fluoroplastic molded sheet, rod, sleeve, tape, sealing ring, diaphragm and parts with metal inserts, etc. Molding is divided into three steps: pre-forming, sintering and cooling. Preforming is the process of adding PTFE powder uniformly into the mould and pressing it into a dense preform at room temperature (i.e., blank), and sintering is the process of heating the preformed product to the melting point and cooling it from sintering temperature to room temperature. Some fluorine plastics are made by pressing at the melting point above the temperature. The molding die is called hot pressing die, and the corresponding PTFE mould is called cold pressing die. Attention should be paid to the effects of compression ratio (4-6) and molding shrinkage (2.6-4.5%) on the products. The best raw material is suspension polymerization resin, the diameter of 20-500 micron soft powder is the best. The presetting pressure is 17-35 MPA, depending on the thickness of the blank, such as 100 mm thick blank, the pressure should be kept for 15 minutes. During sintering, we should pay attention to: the temperature rise rate can be 20-120 ℃ / h, the bigger the product is, the slower the heating rate is, the higher the sintering temperature of suspension resin is 370-380 ℃, the lower the sintering temperature is 360-370 ℃, the higher sintering temperature is, the lower the sintering temperature is, the higher the sintering temperature is. The shrinkage and porosity increase and the sintering time should be controlled properly. In general, the cooling rate is slow, with a speed of 15-25 ℃ / h. In special cases, such as a few thin plates with thickness less than 5 mm or thin-walled tubes pressed into shape, rapid cooling is used only. Sometimes the products are annealed at 100-120 ℃ for 4-6 hours.

Fluoropolymer ETFE Pellet.jpgFluoropolymer ETFE Pellet for insulation layer.jpgFluoropolymer ETFE Resin.jpg

Injection Technology of Fluoroplastic


PFA (tetrafluoroethylene and perfluoroalkyl vinyl ether copolymers), that is, fusible PTFEs, can be molded. The processing temperature is wide, the highest temperature is 425 ℃, the decomposition temperature is more than 450 ℃, and the general controlled processing temperature range is 330-410 ℃. The moisture absorption of the PFA is very small, 0.03, so there is no need to dry. Before injection, the inserts should be preheated to about 140 ℃, the three-segment temperature of the injection tube should be 1: 200-210300-310350-410 ℃, the nozzle temperature is slightly lower than the top temperature of the cylinder, the mold temperature is 140-230 ℃, the injection pressure is 40-90 MPA, Injection speed should be a bit slower, pressure keeping time should not be too long. Cooling time is 40-150 seconds

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Fluoropolymer Plastic Pellet.jpgFluoroplastic Pellet.jpgFluoropolymer FEP Pellet.jpg