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    Does the injection molding machine have back pressure?

    Does the horizontal injection molding machine have back pressure? Both new and old vertical injection molding machines have back pressure adjustment, and the adjustment valve is pipe knob type.

    In the process of plastic melting and plasticization, the molten material moves to the front end of the barrel (metering chamber) from time to time, and more and more, gradually forming a pressure to push the screw backward. In order to prevent the screw from retreating too fast and ensure the average compaction of molten material, it is necessary to provide the screw with a pressure in the opposite direction, which is called back pressure.

    Back pressure, also known as plasticizing pressure, is controlled by regulating the return throttle valve of the injection cylinder. The back pressure valve is set at the rear of the injection cylinder of the pre plasticizing screw injection molding machine to regulate the oil discharge speed of the injection cylinder when the screw rotates and retreats, so as to make the cylinder adhere to a certain pressure; The backward moving speed (resistance) of the screw of the whole motor is controlled by the AC servo valve.

    Benefits of properly adjusting back pressure:

    1. It can compact the molten material in the barrel, increase the density, and improve the stability of glue injection amount, product weight and size.

    2. Properly raising the back pressure can improve the shrinkage of the product appearance and the glue walking around the product.

    3. Slow down the backward speed of the screw, make the molten material in the barrel fully plasticized, increase the mixing average degree of toner, masterbatch and molten material, and prevent the color mixing of products.

    4. It can raise the temperature of the melt, improve the plasticization quality of the melt, improve the mobility of the melt during mold filling, and there is no cold glue grain on the surface of the product.

    5. It can "extrude" the gas in the molten material, reduce the air spray on the surface and internal bubbles of the product, and improve the uniformity of luster.