Views: 8 Author: Site Editor Publish Time: 2025-07-03 Origin: Site
In plastic compounding operations, the performance and longevity of the twin-screw extruder are critical to achieving high-quality products. However, constant mixing and shearing within the barrel and screw elements lead to inevitable wear, forcing manufacturers to frequently replace these components. This not only disrupts production efficiency but also increases maintenance costs.
To reduce the replacement frequency of extruder barrels and screws, it's essential to understand the main causes of wear and adopt strategies to extend their service life.
What Is the Barrel in a Twin-Screw Extruder?
The barrel, along with the screw, forms the core working mechanism of a twin-screw extruder. It houses the melting and compounding of polymer resins, additives, and fillers. Proper interaction between the barrel and screw is essential for effective plasticizing and mixing.
Top 5 Factors That Cause Wear in Twin-Screw Extruder Barrels and Screws
1. Normal Abrasive Wear
During mixing, base resin, additives, and fillers cause mechanical friction. Fillers like calcium carbonate and glass fiber are particularly abrasive, wearing down metal surfaces much faster than molten polymers.
2. Corrosive Wear
Some additives or reactive agents are chemically corrosive and can degrade the inner wall of the barrel, shortening its lifespan.
3. High-Intensity Wear Zones
There are four primary high-wear zones in an extruder:
Feeding zone: Solid materials enter and rub against the barrel wall, causing heavy mechanical wear.
Glass fiber/filler zone: Long glass fibers entangle at the feed port and shear during rotation, forming sharp particles that intensify abrasion.
Middle zone: Due to axial pressure and screw bending (deflection), severe barrel scraping occurs.
Discharge zone: The cantilevered screw end sags under gravity, and when material enters, the screw lifts, causing its edge to rub against the barrel.
4. Operating Conditions: High Temperature and Pressure
Extrusion involves extreme heat, especially with materials like PC (240°C), Nylon (280°C), and PPS (290°C). High temperature weakens metal properties, leading to faster wear.
5. Moisture and Gas Inside the Barrel
Moisture, air, and oxygen in the barrel accelerate wear through oxidation and corrosion, particularly under high temperature and pressure.
How to Extend the Service Life of Barrels and Screws
Since conditions like temperature, pressure, and moisture are hard to control, the best solution is to use more durable materials for manufacturing barrels and screw elements.
Material Options:
Carbon steel
Stainless steel
Alloy steel
Powder metallurgy steel (PM steel)
Among these, powder metallurgy steel stands out due to its superior wear and corrosion resistance. Produced under strict conditions, PM steel offers:
Finer, more uniform grain structure
Minimal segregation of nickel, chromium, and molybdenum
Higher mechanical strength
Longer service life for barrels and screw elements
Conclusion
Understanding the mechanism of barrel and screw wear and identifying key wear zones can significantly reduce unplanned downtime and maintenance costs. By selecting advanced materials like PM steel and optimizing design, manufacturers can improve extruder performance and achieve long-term operational efficiency.
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