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Screw Abrasion Reason
May 04, 2017

1, each kind of plastics, has an ideal plastic processing temperature range, should control the barrel processing temperature, so that close to this temperature range. Granular plastic from the hopper into the barrel, first will arrive at the feeding section, in the feeding section will inevitably appear dry friction, when these plastics are not heated enough, melting uneven, it is easy to cause the barrel lining and screw surface wear increase. Similarly, in the compression and homogenization segments, if the melt state of the plastics is uneven, it will also cause wear and tear increase quickly.

2, speed should be adjusted properly. Because some of the plastics plus reinforcement, such as glass fiber, minerals or other filler materials. These substances are often much larger than molten plastics in the friction of metallic materials. In the injection molding of these plastics, if the use of high rotational speed, in addition to improve the shear strength of plastics, will also strengthen correspondingly to produce more shredded fibers, shredded fibers containing sharp ends, so that the wear force greatly increased. When the inorganic minerals glide at high speed on the metal surface, the scraping effect is not small. So the speed is unfavorable to adjust too high.

3, screw in the barrel rotation, the material and the friction between the two, so that the screw and barrel of the working surface gradually wear: screw diameter gradually narrowed, the barrel diameter of the hole gradually increased. In this way, the screw and the barrel of the diameter gap, with the gradual wear and tear and a little increase. However, due to the barrel front nose and shunt plate resistance unchanged, this increase the extrusion of the material in the flow of leakage, that is, the material from the diameter of the gap in the direction of the flow of the increase. As a result, the production volume of plastic machinery decreased. This phenomenon also causes the increase of the time of the material in the barrel, causing the material decomposition. If it is polyvinyl chloride, the decomposition produced hydrogen chloride gas strengthens the corrosion of the screw and barrel.

4, materials such as calcium carbonate and glass fiber filler, can accelerate the screw and barrel wear.

5, because the material is not plastic evenly, or there is metal foreign material mixing, so that the screw rotation torque force suddenly increased, this torque exceeds the strength of the screw limit, so that screw twist. This is a very bad accident.