Spinneret Design and Technology

Spinneret specifications: material (stainless steel or gold-platinum alloy for filtration), capillary count (50-2000 holes, higher counts for finer deniers), capillary diameter (0.15-0.50 mm determining filament fineness), L/D ratio (length-to-diameter 2-5, affecting polymer flow, orientation), and hole shape (circular, trilobal, pentalobal, hollow, flat, etc. determining cross-section). Cross-sectional shaping: trilobal (Y-shape for luster, soil-hiding in carpet—30-40% of polyester filament), hollow (insulation, moisture management, 20-25% weight reduction), flat (silk-like handle, luster), and multilobal (5-8 lobes for anti-pilling, sparkle effects). Spinneret design criteria: uniform polymer distribution (flow balancing), minimal pressure drop (typically 5-15 MPa), heat transfer optimization, and filtration (removing gel particles >10 μm).