People use high - speed injection molding machines to shorten the injection cycle and improve production efficiency. However, in the process of injection molding products, the slip of the injection molding machine is a big problem. Especially for moisture absorbent material (such as nylon), the high water content of resin will cause the slip of the injection molding machine screw. Improper drying can significantly lower the viscosity of the material, and the water vapor in the cylinder will cause a decrease in the transmission capacity of the screw. This can be used to determine the moisture content of the dried materials before processing, so that the drying level of the material reaches the guarantee value of the supplier.
Injection molding machine screw slip can cause material degradation, thus affecting product quality. What are the reasons for the slippage? How do you "grab" a sliding screw? When the cylinder screw is produced, the material may gather in the feeding port, and it cannot be delivered to the end of the injection machine normally. When the screw is rotated and retreated in the cylinder to transport the material and prepare for the next injection, the screw slip will be produced in the plasticized section.
At this point, the rotation of the screw is still inherited, but the axial movement of the screw will stop, that is, it will be skidding. The slippage of the screw often results in the degradation of the material before the injection. The product quality will be reduced (if the material is missing), and the molding cycle will be prolonged.
Screw slippage of reason is various, probably with the back pressure is too high, the end of the cylinder hot or too cold, cylinder or screw wear, charging period of screw thread too shallow, hopper plan is not reasonable and humid, resin, resin hopper was infarction excessive lubrication, the material is too thin resin and probably reworked material not reasonable cutting and other factors.
The cooling of the end of the cylinder is one of the main reasons for the slippage of the screw. The barrel of the injection machine is divided into three parts. At the end, the feeding section, the granule is in the process of heating and compression, forming a layer of melt film to stick to the screw. Without this film, the granule is not easily transported to the front end.
The material of the feeding section of the injection molding machine must be heated to the critical temperature to form the melting film at that juncture. However, the duration of the material in the feeding section is too short to reach the required temperature. This environment is usually produced on small injection machines. Too short a stay can cause the melt of the polymer and the incompleteness of the inclusion process, which causes the screw to slip or stall.