(1) A large amount of regrind is added to the plastic.
(2) The screw barrel is coated with glue, and the plastic wraps around the screw and rotates with it.
(3) The wear of the extruder screws and barrels or the rubber ring causes the plastic to leak and not be transported to the front end of the barrel.
(4) The temperature control is not accurate, and the temperature at the back end of the barrel is too high. You can adjust the temperature setting and check whether the cooling water circuit is blocked.
(5) The feed-port of the barrel is blocked. You should check whether there is any melted plastic block sticking here.
(6) The plastic particles are too large, which will cause bridge formation. The plastic can be crushed again.
(7) There is too much oil added to the plastic, which causes the extruder screw to slip.
(8) If the newly replaced screw does not feed, it may be the design of the screw and the feed-port of the barrel is not appropriate. If the feeding section's screw groove of the screw barrel is too shallow, the screw cannot drive the plastic forward when rotating, or the amount of material conveyed is small. For the barrel, the design of the feed-port is important.
Since the twin screw has starve-fed extrusion, and there are few cases of not feeding. The following methods are more commonly used. You can set an eccentric feed-port, and use an SK screw element with a large pitch in the feeding section. The constant cooling for the joint barrel and other methods can ensure smooth feeding. A forced feeding device can be added for difficult feeding.
(1) If there is a nitriding layer on the extruder barrel with increased diameter due to wear, the inner hole of the barrel can be directly bored and ground to a new diameter size. Then, a new screw can be prepared according to this diameter.
(2) The inner diameter of the barrel can be machined and trimmed to recast the alloy, the thickness is between 1~2mm, and then finished to the size.
(3) Normally, the homogenized section of the barrel wears quickly. This section (5~7D long) can be bored and trimmed, and then equipped with a nitrided alloy steel bushing. The diameter of the inner hole refers to the screw diameter, and it should be left in the normal matching gap for processing.
After the extruder screw barrel is repaired, there is no need to modify the plasticization parameters of the whole machine. Its service life is much longer than the conventional material parts, which brings great wealth to the rubber and plastics industry.
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