Technical Details of Three‑Start ElementStructural Geometry• Three helical screw flights, fully intermeshed with mutual wiping and complete self-cleaning performance. • Under the same outer diameter, its screw channel depth is notably smaller than twin-start and single-start elements, forming thin material layers. • Larger root diameter enables matching with larger-diameter shafts and improves overall torque resistance. • The inner bore adopts involute spline. • Model marking example: TH‑30/30 (three-start, pitch 30 mm, element length 30 mm). Multiple pitch options available. Large pitch focuses on conveying; small pitch prioritizes pressure build-up and shearing. Material Configuration• 38CrMoAlA nitrided steel: For general engineering plastic compounding. • WR5: For glass fiber and mineral high-wear working conditions. • WR13: Wear and corrosion resistance for battery materials and corrosive melts. • Nickel-base alloy: For highly corrosive reactive extrusion. Manufacturing Process• Integral forging and quenching & tempering heat treatment. • CNC grinding of three-start thread profile with strict control of meshing clearance. • Smooth fillet transition at thread root to reduce material adhesion. • Guarantee torque bearing capacity of spline. Process Parameter Characteristics• Shear level: Medium shear, higher than twin-start SE/SK and lower than KB kneading blocks • Conveying capacity: Forward conveying. Small free volume leads to poor solid feeding capacity, yet strong melt conveying and pressure-building performance • Shear heat: Medium. Thin material layer enables fast heat transfer, and heat can be easily removed by barrel • Mixing type: Weak dispersive mixing + moderate distributive mixing • Self-cleaning: Excellent, no stagnant dead zones • Residence time: Moderate • Heat transfer performance: Outstanding. Thin material layer enhances heat exchange between melt and barrel and accelerates melting and plasticization. | Functions of Three‑Start Element•Enhance melting and plasticization and improve heat transfer efficiency. Shallow screw channels create thin melt layers, enlarge heat exchange area between material and barrel, and achieve high heat transfer efficiency to promote rapid and sufficient resin melting. It is mostly applied in the middle and late melting sections to improve plasticization quality. • Melt conveying and pressure build-up. It features good pumping and pressure-building capacity in melt zones. Installed in metering section to stabilize melt pressure and provide steady material flow for die. Not suitable for solid feeding due to low solid filling and poor material grabbing. • Moderate shear for auxiliary mild dispersion. Compared with twin-start threads, it delivers higher shear rate to help break mild agglomerates of fillers and color pigments. Its shear intensity is lower than kneading blocks without severe overheating. • Optimize melt condition before devolatilization. Installed upstream of vacuum ports, thin melt layer creates large renewed melt surface area, facilitating removal of small-molecule volatiles and improving devolatilization efficiency. | 
