Injection molding machine screw slip can cause material degradation, thus affecting product quality.How to prevent slipping?Here is the letter to you.：
When the screw is skidding, the material may gather in the feeding port, and cannot be delivered to the end of the injection machine normally.When the screw is rotated and back in the cylinder to transport the material and prepare for the next injection, the screw slip will occur in the plasticized section.At this point, the rotation of the screw is still continuing, but the axis of the screw is stopped, that is, skidding.The slippage of the screw often leads to the degradation of the material before the injection, the product quality will decrease (if the material is missing), and the molding cycle will be prolonged.
Screw slippage of reason is various, with high back pressure, cylinder end hot or too cold, cylinder or screw wear, charging period of screw thread too shallow, hopper design is not reasonable and hopper blocked, excessive lubrication, resin, resin damp material is too fine or resin and reworked material cutting factors such as unreasonable.
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, in the process of heating and compression, a layer of melt film will be formed to stick to the screw.Without this thin film, the grain is not easily transported to the front end.
The material in the feeding section must be heated to the critical temperature to form the critical melt film.However, the duration of the material in the feeding section is too short to reach the required temperature.This usually happens on small injection machines.Too short duration can cause the fusion and mixing process of the polymer to be incomplete, leading to slippage or stall.