Worn Repair and Use of Screw and Barrel

Ⅰ. How to repair the wear of screw and barrel?


For screw and barrel wear, here is a refurbishment and repair method to teach you:


ⅰ. When the extruder screw is twisted and broken, the outer diameter of the extruder screw should be determined according to the actual inner diameter of the extruder barrel and the matching clearance required by the theory.


ⅱ. Before repairing the screw diameter of the extruder because of the smaller wear surface, the surface treatment of the worn extruder screw should be smooth and clean, and then spray wear-resistant alloy to the wear part. After spraying, the size of the extruder screw should be greater than the size of the original screw, and then grinding to the required size. This kind of repair can be carried out in a professional spray factory, and the cost is relatively low.


ⅲ. If the screw thread part of the extruder is seriously worn, the size is reduced or the damaged part is larger, it can be repaired by surfacing with wear-resistant alloy. Generally, it can be 2~3mm thick, and then grind it to the required size. Surfacing repair method is expensive, so it should be carefully considered.


ⅳ.If the size of the extruder screw is not changed after wear, it can also be repaired by plating hard chromium on the surface. Hard chrome layer is resistant to wear and corrosion. However, if the base is not well treated or the chrome layer is thick, the chrome layer will easily fall off.



Ⅱ. Matters needing attention when using screw and barrel


ⅰ. Avoid idling and slipping of the extruder screw.


ⅱ. Avoid POM and PVC mixed into the barrel at the same time. At the melting temperature they will react, causing serious industrial accidents.


ⅲ. Avoid foreign matter falling into the barrel and damaging the extruder screw and barrel. Prevent metal fragments and debris from falling into the hopper. If processing recycling materials, it is necessary to add a magnetic hopper to prevent iron filings into the barrel.


ⅳ. Do not start the machine when the cylinder does not reach the pre-adjusted temperature. The newly opened electric heating generally requires that the temperature reaches the set value for 30 minutes before operating the extruder screw.


ⅴ. Make sure that the plastic in the cylinder is completely melted when use the anti-salivating, so as not to damage the drive system parts when the extruder screw goes back.


ⅵ.When the molten plastic temperature is normal, but continue to find molten plastic black spots or discoloration, it is necessary to check whether the non-return screw(rubber ring, meson) is damaged.


ⅶ. If the machine is shut down for more than half an hour each time, it is necessary to close the feed port and clean the material in the cylinder, and then set insulation.


ⅷ. When using new plastic, the remaining material of the cylinder should be cleaned. When using POM, PVC, PA+GF and other materials, it should try to reduce the degradation of raw materials, and rinse with ABS and other nozzle materials in time after shutdown.

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