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Why does the screw of the horizontal injection molding machine slip?

Oct 07, 2019

In the plastics industry, injection molding machines are the aids for the production of products, but they are decisive. In order to shorten the finished product injection cycle, manufacturers use high-speed injection molding machines to improve production efficiency. However, the high-speed injection molding machine will have screw slip phenomenon when producing finished products, which will cause certain problems for the production of the enterprise. The principle of screwing the screw of the injection molding machine is that after the screw feeds the material to the mold or the material enters the feeding port, the screw slips and cannot enter or retreat. The material gathers at the feeding port and cannot be normally transported to the end of the injection machine. Stage. There are many reasons for the plasticizing section, and the excessively cold end of the barrel is one of the main causes of screw slip.

 

The barrel of the injection molding machine is divided into 3 sections, and the end is a feeding section. During the heating and compression process, a layer of melt film is formed on the screw. Without this film, the pellets are not easily transported to the front end. . The high water content of the resin is also the main cause of the screw slip of the injection molding machine. Especially for the hygroscopic material (such as nylon), improper drying will also significantly reduce the viscosity of the material, and water vapor will occur in the barrel, thus causing the screw The delivery ability is reduced. Therefore, when using materials such as PA, PC, PET, etc., the materials should be properly dried according to the instructions.

 

There are many reasons for the screw slip. When the back pressure is too high, the end of the barrel is too hot or too cold, the barrel or screw is worn, the thread of the feeding section is too shallow, the hopper is infested, the resin is wet, the resin is excessively lubricated, and the material is too fine. These problems, the screw slip causes the material to degrade, and there is a shortage of materials that we often say. The prolonged molding cycle of these problems directly affects product quality is understandable.

 

There are many ways to solve the screw slip, in which the raw material is sufficiently dried, the temperature of the feed port is lowered, the degree of screw wear is regularly checked, the screw speed is appropriately adjusted, and the most important method. The customer will do the corresponding preparation work in the early stage of injection molding, and the efficiency will be relatively improved.