Material and Metallurgy Solutions
Application-Specific Materials for Wear, Corrosion, and High-Torque Performance.
Condition-matched material selection for twin-screw core components
In twin-screw extrusion, the failure mechanisms are entirely different due to the use of different formulation systems. Wear and corrosion are the dominant factors in certain conditions, while fatigue, impact, and corrosion are frequently observed in conjunction. There is no universal material for essential components. What is crucial is a material-matching strategy that is specifically designed to align with the actual operating conditions. Lesun develops a multi-condition material solution for screw elements, barrels, and shafts that optimizes cost, performance, and service life on the basis of extensive application experience.
Screw Elements
Highly-filled modified materials
A significant quantity of inorganic particles perpetually scour the surfaces of the elements in high-filler processing, particularly in the pressure-build, mixing, and conveying zones. This leads to the degradation of conveying efficiency and processing stability by causing tooth-tip wear, working-surface erosion, and a widening of element clearance over time. The selection of materials is based on their ability to resist abrasive wear while maintaining structural stability under high load. In critical working zones, a reinforced wear-resistant design is employed to ensure a long wear life without the brittleness that leads to early failure.
Glass-fiber-reinforced engineering plastics
The metal surface is continually cut by glass fiber under high shear and high-speed rotation. Wear accelerates significantly as fiber content and output increase, with the most severe effects occurring in high-dispersion zones, reverse elements, and kneading blocks. Here, the selection process prioritizes the balance of wear resistance and impact resistance, rather than solely hardness. This approach enhances long-term wear resistance by optimizing the material structure to prevent localized chipping and abnormal failure.
Color and functional masterbatch
Equipment is typically operated continuously for extended periods in masterbatch and additive production. Dispersion-quality requirements are stringent, and certain pigments and functional fillers are highly abrasive. Selection maintains consistent blending and dispersion even after extended operation by balancing processing stability with wear resistance.
Recycled plastics
The composition of recycled feedstock is extremely variable and complex. The risk of fatigue is increased by the frequent changes in processing burdens, while localized impact wear is caused by impurities, foreign matter, and uncertain particles. The selection process emphasizes overall durability, which is achieved by integrating fatigue, impact, and wear resistance to manage the uncertainty of a complex system.
Flame-retardant and corrosive systems
Corrosive media can be produced by high temperatures in flame-retardant materials, halogen-containing systems, and certain special polymers. The metal surface integrity is initially compromised by corrosion, which subsequently accelerates wear. The selection process prioritizes corrosion resistance while maintaining the requisite mechanical strength and wear resistance, thereby achieving a balance between corrosion protection and service life.
Barrels
High-wear conditions
The barrel is subjected to sustained scouring from high-speed material flow, with wear concentrating in the feed zone, open zones, and high-pressure zones. The selection process is designed to increase the resistance of the contact-surface to wear while simultaneously preserving the bore's overall structural strength, ensuring that it remains dimensionally stable during extended operation.
High-corrosion conditions
The initial targets of corrosive media are exposed zones, venting zones, and high-temperature residence zones. The bore surface becomes roughened as corrosion accumulates, resulting in a combined corrosion-and-wear failure. The selection process emphasizes corrosion resistance by employing specialized surface-protection technology to enhance long-term resistance to chemical attack.
Long-cycle continuous production
The overhaul intervals and operating cost of large continuous facilities are directly influenced by barrel life. Customers prioritize stability during extended operations in addition to wear resistance. The selection process in this case is centered on the concept of balanced-life design, which aims to mitigate the risk of unanticipated downtime by enhancing the durability of critical zones.
Shafts
High-torque conditions
The shaft is subjected to a greater torsional burden over the long term as equipment advances toward higher torque. Spline wear, plastic deformation, or fatigue fracture are all potential consequences of an insufficient strength reserve. The selection process is centered on the provision of a sufficient toughness reserve, as well as high strength and torsional capacity.
High-frequency start-stop conditions
Fatigue damage is more easily caused by the transient impact loads of frequent starts and stops than by constant running, and micro-cracks can progress to structural failure over time. Selection shifts toward fatigue resistance and impact toughness, which enhances long-term reliability by enhancing material toughness and microstructural uniformity.
High-load engineering-plastics conditions
The shaft carries a sustained high load during high-viscosity, high-output operation. At cold start, the peak transient torque frequently exceeds the normal running torque. The selection process ensures that power is transmitted stably over the long term by balancing high strength, high durability, and fatigue resistance.
Summary
The precise match between operating demand and material performance is what truly determines service life. Lesun employs the wear mechanism, corrosion mechanism, and load characteristics to determine the most appropriate screw-element, barrel, and shaft material solution, thereby achieving the optimal balance of equipment reliability, service life, and total operating cost.