Some plastics need to be vented in the shooting tank du […]
Some plastics need to be vented in the shooting tank during injection moulding to allow the gas to escape. In most cases these gases are only air, but they may be melted moisture or monomolecular gases. If these gases are not released, the gas will be compressed by the melt and brought into the mould, which will expand and form bubbles in the product. To drain the gas before it reaches the nozzle or mould, reduce or reduce the screw root diameter* to decompress the melt in the shooting tank.
Here, the gas can be discharged from holes or holes in the shooting tank. The diameter of the screw root is then increased and the melt of the volatiles is directed toward the nozzle. The injection moulding machine equipped with this facility is called a vented injection moulding machine. Above the vented injection moulding machine, there should be a good smoke ejector for the flammable burner to remove potentially harmful gases.
In order to obtain a high quality melt, the plastic is uniformly heated or melted and thoroughly mixed. Use the right screw to properly melt and mix, and have enough pressure (or back pressure) in the shooting tank to achieve mixing and thermal consistency. Increase the resistance to oil return* to create back pressure in the firing tank. However, the screw takes longer to reset, so there is more wear and tear in the injection moulding machine drive system. Keep back pressure as much as possible, isolated from air, and also require the same temperature and mixing level.