Zhoushan Jed Machinery Co.,Ltd

Professional extruder screw product manufacturing and trade service provider in China


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Reasons for screw wear and maintenance precautions

 Cause of wear:
 1. Each plastic, there is an ideal plasticizing processing temperature range, should control the barrel processing temperature, so that it is close to this temperature range.  Granular plastic from the hopper into the barrel, the first will reach the feeding section, in the feeding section will inevitably appear in the friction, when the plastic heat shortage, melting uneven, it is easy to cause the barrel wall and screw surface wear increase.  Similarly, in the compression and homogenization sections, if the melting state of the plastic is disorderly and uneven, it will also cause faster wear.
 2. The speed should be adjusted properly.  Because some plastics are fortified, such as glass fiber, minerals or other filling materials.  The friction of these materials against metal materials is often much greater than that of molten plastic.  In the injection of these plastics, if with a high speed, will improve the shear force of the plastic at the same time, will also strengthen the corresponding more torn fibers, torn fibers contain sharp ends, so that the wear force is greatly increased.  When inorganic minerals slide on the metal surface at high speed, the scraping effect is not small.  So the speed should not be set too high.
 3. The screw rotates in the barrel, and the friction between the material and the two makes the working surface of the screw and the barrel gradually.  Wear: the diameter of the screw gradually shrinks, the diameter of the inner hole of the barrel gradually increases.  In this way, the screw and barrel.  Diameter gap, with the gradual wear and tear of the two gradually increase.  However, because the front of the barrel head and the resistance of the shunt plate does not change, this increases the leakage flow of the extrusion material forward, that is, the material flow from the diameter gap to the feed direction increases.  As a result, the production of plastic machinery decreased.  This phenomenon makes the material in the machine.  The dwell time in the cylinder increases, resulting in material decomposition.  If it is polyvinyl chloride, the decomposition of hydrogen chloride gas to strengthen the corrosion of the screw and barrel.  .
 4. Material such as calcium carbonate and glass fiber filling material, can speed up the wear of screw and barrel.
 5. Because the material is not plasticized evenly, or there are metal foreign bodies mixed into the material, the screw rotation torque force suddenly increased, this torque beyond the strength limit of the screw, the screw torsion.  This is an unconventional accident damage.
 Precautions for Maintenance:
 1. Do not start the machine when the screw has not reached the pre-adjusted temperature.
 2. Prevent metal debris and sundries from falling into the hopper. If processing and recycling materials, it is necessary to add magnetic hopper to prevent iron filings from entering the barrel.
 3. When using anti-salivation, make sure that the plastic in the material is completely melted, so as to avoid damage to the transmission system parts when the screw is backward.
 4. When using the new plastic, the residual material of the screw should be cleaned.
 5. When the temperature of molten plastic is normal but it is constantly found that the molten plastic has black spots or discoloration, the rubber snail should be checked.
 6. In the processing, try to make the material plasticizing uniform, do not let the metal foreign matter into the material, reduce the screw.  Rotational torque force.



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