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Understand the injection molding process of PE pipe fittings

Ningbo Lianda Plastic Pipe Co.,Ltd | Updated: Aug 27, 2018

The three important process conditions for PE pipe injection molding are temperature, pressure and time.

Temperature: PE pipe parts are thick-walled parts, so as to avoid internal stress caused by excessive temperature difference during cooling. The temperature of the barrel should be lower than the temperature distribution of the barrel. Generally, the temperature from the hopper to the nozzle rises from low to high to make the plastic temperature. Smoothly rise to achieve the purpose of uniform plasticization. In order not to overheat the plastic, the temperature near the nozzle section is slightly lower. The mold temperature has a great influence on the intrinsic properties and appearance quality of the product. For PE pipe fittings, in addition to the filling rate, the mold temperature will directly affect the crystallinity and crystal configuration of the product.

Therefore, the PE pipe mold uses medium mold temperature. For polyethylene (PE) materials, the cooling rate is suitable, the plastic has moderate crystallinity, and has good physical and mechanical properties.

Pressure: The pressure during the injection molding process includes back pressure and injection pressure. When the screw type injection molding machine is used, the pressure of the top melt of the screw when the screw is rotated backward is called back pressure. The back pressure is increased, which will make the PE pipe fittings. Temperature uniformity and mixing uniformity are improved. Increasing the back pressure can discharge the gas in the melt and increase the compaction of the melt, thereby increasing the amount of injection of the machine. For PE raw materials, increasing back pressure can increase melt temperature, composition and color uniformity.

Time: Injection time and cooling time have a decisive influence on the quality of the product throughout the molding cycle.