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Do you know which part of the twin-screw extruder barrel is the most worn?

April 06,2022

When visiting the modification plant, I happened to see the staff checking the working condition of the twin-screw extruder and replacing the extruder barrel liner, and when I took it out to see, the liner wall was badly worn and there were grooves everywhere.

Curious, the staff introduced, the barrel inner wall and twin-screw components, plastic particles, auxiliary materials, additives in the co-mingling process, by friction so that the barrel inner wall and twin-screw components are subject to different degrees of wear, especially when adding glass fiber filler, the barrel inner liner is replaced more frequently, sometimes even three months to replace.

In the modification enterprise,twin-screw extruderis the plastic particles, auxiliary materials and additives mixing, blending, melting, shearing, extrusion and pelletizing equipment, is the terminal equipment for the production of special materials, its importance is obvious, frequent replacement of the barrel, not only increases the cost of equipment, but also increases the cost of time and reduces production efficiency. This is certainly a thing that needs to be improved.

▲Twin-screw extruder barrel and screw

The barrel (barrel) is one of the two main working parts of a twin-screw extruder, the other being the screw. Only when thebarrel and screwform a pair of friction groups can the plastic, auxiliary materials and additives be fully mixed. How to extend the service life of the barrel, reduce the frequency of replacement, while still meeting the production needs of enterprises. We need to understand the factors that affect the life of the barrel and its wear principle in order to effectively solve this problem.

▲ Photo of cylinder liner wear

5 major factors affecting the life of the barrel
1. General wear and tear
2. Corrosion wear
3. High intensity wear (heavy wear area)
4. Working condition (temperature, pressure influence)
5. Water, air, oxygen and other component gases in the cylinder

4 heavy wear zones of extruder barrel (12-section barrel as an example)

1. Dosing area

▲Dosing area

The bottom sleeve connecting shaft connects the whole screw, here is where the first section of the barrel, usually also the feeding area, and mechanical wear is more powerful. In the first section to add calcium carbonate, talc, etc., these additives have not yet melted, basically in a solid state, the inner wall of the barrel and the solid direct friction, making the inner wall wear is very strong, this is the first heavy wear area.

2. Add fiberglass area

▲Add fiberglass area

In the 5th, 6th and 7th threaded element area, where the glass fibers are usually added, the glass fibers are filaments that strangle the sharp corner of the eight holes at the fiber inlet, creating deep grooves in the barrel; in addition, the glass fibers are sheared at high speeds, resulting in more torn fibers, which contain sharp ends and greatly increase the abrasive force and wear the barrel wall.

3. Middle area

▲Middle area

The pressure on the top of the twin screw makes the screw in the middle area bend at high speed, and the deflection (bending amount) is the largest, and the sweep is very strong, and the wear on the barrel is obvious.

4. Rod head area

▲Pole head area

The screw in the top area is in a cantilevered state, and is affected by gravity and sags downward. After the material enters, it will hold up the top of the screw, resulting in a small gap below and a large gap above, and the outer diameter of the screw rubs against the inner wall of the barrel, and the lower part of the inner wall of the barrel is scraped very hard, and the grooves are not changed for a long time.

Is there a more wear and corrosion resistant barrel solution

After the above introduction, you can understand the twin-screw extruder barrel wear factors, barrel weight wear area, if the frequent replacement of the barrel, the impact on business production is not small. Then there is no more wear and tear, more corrosion-resistant solutions on the market.

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