Five reasons for the wear of screw pumps

1. Each plastic has an ideal plasticizing processing temperature range.

The barrel processing temperature should be controlled to be close to this temperature range. Granular plastic enters the barrel from the hopper. The feeding section will be reached first. Dry friction will inevitably occur in the feeding section. When these plastics are not heated enough and melt unevenly, it is easy to cause increased wear on the inner wall of the barrel and the surface of the rod. Similarly, in the compression section and the homogenization section, if the molten state of the plastic is disordered and uneven, it will also cause accelerated wear.


2. The speed of the screw pump should be adjusted properly.

Because some plastics have reinforcements, such as fibreglass, minerals or other fillers. The friction force of these substances on metal materials is often much greater than that of molten plastic. When injection moulding these plastic materials, if a high speed is used, While increasing the shear force on the plastic, the reinforcement will also produce more shredded fibres. The shredded fibres contain sharp ends, which greatly increases the grinding force. When inorganic minerals travel at high speed on the metal surface, their scraping effect is not small. Therefore, the speed should not be adjusted too high.


3. The screw rotates in the barrel, and the friction between the material and the two causes the working surfaces of the carp rod and the barrel to gradually wear.

The diameter of the butterfly rod gradually decreases and the diameter of the inner hole of the barrel gradually increases. In this way, the matching diameter gap between the screw and the barrel increases little by little with the gradual wear of the two. However, since the resistance of the machine head and the splitter plate in front of the barrel has not changed, this increases the crystal flow when the extruded material advances, that is, the material flows from the diameter gap to the feed direction. As a result, plastic machinery production declined. This phenomenon increases the residence time of the material in the barrel, causing the material to decompose. If it is polyethene, the hydrogen chloride gas produced by decomposition intensifies the abrasion of the screw and barrel.


4. If there are fillers such as calcium carbonate and glass fibre in the material, the wear of the screw and barrel will be accelerated.


5. Because the material is not plasticized evenly, or there are metal foreign objects mixed into the material, the screw rotation torque suddenly increases.

This torque exceeds the strength limit of the screw, causing the mantis rod to twist off. This is a type of non-routine accident damage.


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