How Does the Bimetallic Composition Enhance Screw Barrel Performance?

The bimetallic composition enhances screw barrel performance through several key mechanisms:

1.Improved Wear Resistance: The outer layer of bimetallic screw barrels often incorporates materials like tungsten carbide or other hard alloys. These materials are renowned for their exceptional hardness, providing a robust defense against the abrasive wear caused by the continuous movement of plastic materials during extrusion or injection molding. This heightened wear resistance translates into a prolonged lifespan for the screw barrel and reduced downtime for replacements.
2.Enhanced Corrosion Resistance: Bimetallic coatings frequently include corrosion-resistant alloys such as nitrided steel or bimetallic alloys with high chromium content. This fortification shields the screw barrel from corrosive elements present in certain plastic formulations, ensuring longevity and sustained performance in corrosive processing environments.
3.Optimized Thermal Conductivity: Bimetallic screw barrels leverage the strategic combination of materials to achieve superior thermal conductivity. For instance, the inner core may be made of high-conductivity materials like copper alloys, facilitating efficient heat transfer during plastic processing. This optimization leads to better temperature control, reduced energy consumption, and enhanced overall processing efficiency.
4.Reduced Friction and Drag: The outer layer of bimetallic screw barrels, often composed of materials with low coefficients of friction like chromium-based alloys, minimizes friction between the screw and barrel surfaces. This reduction in friction not only improves processing efficiency but also lowers the amount of heat generated, contributing to a cooler operating environment and decreased wear on components.
5.Tailored Material Properties: Manufacturers can choose materials for the inner and outer layers based on the specific demands of the processing application. For example, when processing highly abrasive materials like glass-filled plastics, a bimetallic screw barrel might have a wear-resistant alloy on the surface to withstand the abrasive forces, while the core retains toughness and resilience.
6.Increased Strength and Toughness: The bimetallic composition allows for a combination of high-strength materials (such as tool steels) in the inner core and tough outer layers. This synergistic combination enables the screw barrel to endure the mechanical stresses associated with high-pressure injection molding or extrusion of tough materials without succumbing to deformation or failure.
7.Temperature Resistance: Bimetallic screw barrels often integrate heat-resistant alloys such as Inconel or other heat-treated materials in their composition. This ensures the screw barrel can maintain structural integrity and dimensional stability even under extreme temperatures, preventing issues like thermal expansion or deformation during high-temperature processing.
8.Extended Service Life: The cumulative effect of wear resistance, corrosion resistance, and optimized thermal performance contributes to an extended service life for bimetallic screw barrels. In practical terms, this means fewer instances of unscheduled downtime and lower maintenance costs, providing a significant advantage for manufacturers.
9.Compatibility with Various Materials: The versatility of bimetallic screw barrels allows them to handle a wide array of materials, from standard polymers to highly abrasive or corrosive compounds. This adaptability makes them suitable for diverse industrial applications ranging from the production of standard plastic products to specialty materials with challenging processing requirements.
10.Consistent Performance Over Time: By addressing wear, corrosion, and thermal challenges, bimetallic screw barrels ensure consistent performance over prolonged periods. This reliability is crucial for maintaining consistent product quality, meeting production schedules, and ultimately enhancing the overall efficiency of plastic processing operations.

Twin extruder Bimetal screw and barrel
The bimetallic barrel for single screw extruder is a kind of barrel spray 2-5mm thick alloy coat on the barrel inner wall which has excellent corrosion resistance, abrasion resistance and high working temperature. And its useful service life is greatly improved contrast to common nitrided barrel. Bimetal has more obvious advantages when processing special plastics to enhance the abrasion life, such as engineering plastics, fluoride plastics, PPO etc. Our company use special alloy powders being sprayed and welded on the top of screw flights, and use different alloys and welding methods.