Injection molding machine screw barrel process settings

    The end of the barrel is too cold is one of the main cause screw slippage. The cylinder of the injection molding machine is divided into three sections, in the end, i.e. the feed zone, the pellets in the heating and compression process, will form a layer of the melt film to stick to the screw. Without this film, the pellet is not easily transported to the distal end.

    The feed zone of the material must be heated to the critical temperature to form a critical layer of the melt film. However, typically the material is very short residence time in the feed zone can not reach the required temperature. This situation is typical in the small injection machine. Duration too short to cause the polymer melting and mixing process is not complete, resulting in screw slippage or STALL.

    There are two kinds of simple ways to determine whether the screw slipping. One method is to add a small amount of the material to the end of the barrel in order to detect the temperature of the melt. If the duration is too short, the melt temperature will be less than the cylinder temperature set point. The second method is to check the products: If the products on the pattern of light and dark stripes, which means that the material in the barrel without mixing.

    Upon the occurrence of screw slippage, one solution is to raise the temperature of the feed zone of the barrel, no obstacle until the rotation of the screw and retraction. To achieve this goal, barrel temperature may need to be increased to exceed the recommended set point.

    High back pressure can also lead to stagnant or slipping of the screw. Raise the back pressure setting will raise the energy applied to the material. If the back pressure is set too high, the screw will not have enough pressure to overcome the back pressure, thus unable to transport materials to the front. This case, when the screw rotation in a certain position without retraction, it will be interested in the material do more work, and thus significantly improve the melt temperature, resulting in a decline in the quality of products and the prolongation of the molding cycle. The back pressure of the melt can be controlled by adjusting the valve of the injection cylinder.